Scrubber FAQ 3.0 (2/8/09) (no reply; read only)

[santamonica]

ALGAE SCRUBBER FAQ 3.0
(2/8/09)
Because there are no links to other sites, I'll just post the new scrubber FAQ here, so it does not disrupt the scrubber thread. If you want to reply, don't do it here... do so on the scrubber thread instead:
https://forums.saltwaterfish.com/t/330606/mega-powerful-nitrate-and-phosphate-remover-replaces-skimmer-refugium-everything
Part 1 of 11:
Topics:
Scrubber Basics
Scrubber Configurations
Scrubber Lighting
Scrubber Flow
Scrubber Materials
Scrubber Results
Scrubber Comparisons
Scrubber Applications
Scrubber Advanced Topics
Miscellaneous
Scrubber Basics:
Q: What are algae scrubbers?
A: Scrubbers are devices which use light and flowing water to remove the "bad" things from your aquarium water, while leaving the "good" things (food) in.
Q: What are these scrubbers called?
A: They are called Scrubbers, Algae Turf Scrubbers (ATS), Algae Scrubbers, Algae Filters, Turf Scrubbers, and Turf Algae Filters. They are all the same thing.
Q: Do I need one?
A: If you have nuisance algae growing in your tank, then an algae scrubber will remove it.
Q: Will a scrubber cause more algae to start growing in my display?
A: No. A scrubber will only remove algae from your display.
Q: How long does it take to get results?
A: Typically, the nitrate, phosphate and nuisance algae will start reducing after you have cleaned off a full screen of algae two or three times. However, even you still clean it weekly, it may take a few weeks for the screen to be completely full for the first time. On average, most people solve their nitrate, phosphate and nuisance algae problems within eight weeks, and some people who have very strong lights (within 4" (10cm) of the screen) do so within four weeks. Strong lights and weekly cleaning are the keys.
Q: How big of a scrubber do I need?
A: Start with one square inch (6.25 square cm) of screen, with a light on both sides, for every U.S. gallon (3.8 liters) of water in your display tank. Thus a 100 gallon display tank would need a screen 10 inches by 10 inches (100 square inches), with a light on both sides. If you can only put a light on one side, then you need to double the screen area, and also double the lighting on that one side. You don't need to include the volume of the sump, unless it also has livestock in it that you feed.
Q: Will a scrubber harm my corals?
A: No. As a matter of fact, corals like a lot of food in the water, and they also like low levels of nitrate and phosphate. That's exactly what scrubbers provide. This applies especially to SPS corals.
Q: Will a scrubber work in freshwater?
A: Absolutely. Same benefits, similar to plants, but in a more compact space. You just have to keep your CO2 levels up.
Q: I've heard that scrubbers will cause your water to turn yellow.
A: Not if cleaned weekly in your sink. Yellowing is caused by cleaning the screen while it's still in your system (the broken algae then drains into your water), or by not cleaning weekly (in which case the underlying algae gets covered and shaded by newer algae, and dies).

 

[santamonica]

Part 2 of 11:
Q: Are scrubbers noisy?
A: Not when built properly. The screen should go into the sump water slightly, and the water should flow smoothly down the screen, with no spraying, splashing or noise. Your pumps should be the only thing you hear.
Q: Do they smell?
A: When running, they do not smell at all. When cleaning them in your sink, there is an "ocean" smell. Nothing as bad as cleaning a skimmer cup, though.
Q: I'm currently building my tank. Should I wait to install my scrubber?
A: No. Scrubbers eat nitrate, phosphate and ammonia, and that's just what cycling produces. By starting a scrubber early (even during cycling), the screen will be ready for adding livestock sooner.
Q: I'm still designing my system. What other filtering devices besides a scrubber should I buy?
A: Since you don't have filters set up yet, why not start with just a scrubber, and then monitor your nitrates and phosphates weekly as you add livestock. If you reach a point where your scrubber can no longer keep nitrate and phosphate at undetectable levels, you can then decide to either build a more powerful scrubber, or buy other filtering devices.
Q: Are water changes still needed if I use a scrubber?
A: If the purpose of the water change is to reduce nitrate or phosphate, or to help reduce nuisance algae in the display, then no. If the purpose of the water change is for anything else, then yes.
Q: Where can I buy a scrubber?
A: Nobody currently manufactures or sells scrubbers. If you know of someone who is good at building things using acrylic, lighting and pumps, tell them they should be the first.
Q: Can someone build one for me?
A: There is a list of builders on the Algae Scrubber site.
Q: What's the most important thing that I need to pay attention to when building my scrubber?
A: The lighting. It needs to be the most powerful you can afford/stand/deal with. It makes the difference between a tank that has "not much algae", and one that is "spotless".
Q: Do I need to seed my screen to get it to grow?
A: No. All screens will grow by themselves. But rubbing some algae into the screen (i.e., "seeding") may speed it up a few days. Don't leave any algae on the screen, however; after rubbing it in, wash the rest off in the sink. The spores will remain, but you won't see them.
Q: How do you clean a scrubber screen?
A: Basically, you clean 1/2 of it every week. This allows some filtering to be taking place all the time, since half of it will have algae while the other half starts growing again. You clean it by removing the screen, taking it to your sink, and running tap water over it while gently removing the algae. You don't remove all the algae, however, because you want it to grow back quickly.
Q: How often do you clean it?
A: Once a week, no matter what. This is probably the biggest hassle with scrubbers, and when it is not followed, it's the biggest reason why a scrubber is not working as good as it should. When the algae gets too thick on the screen, it blocks the light from getting to the bottom layers. Thus, the bottom layers die, and put nitrate and phosphate and cloudiness into the water. Weekly cleaning eliminates this. If your screen is smaller than it should be, or if your nutrients are very high in your tank, your screen might fill up and need cleaning in just a few days.
Q: I have a fish-only tank with large fish, and I don't care about small food particles floating around in the water. Do I need a scrubber?
A: Maybe not. If you don't mind cleaning the nuisance algae off the glass (which is caused by Inorganic Nitrate and Inorganic Phosphate), then a skimmer may be fine. But if you are trying to eliminate nuisance algae, and glass cleaning, then you'll need a scrubber in addition to a skimmer.

 

[santamonica]

Part 3 of 11:
Scrubber Configurations:
Q: What is the best type of scrubber to build?
A: For most new aquarists, simple and cheap are best. Simple configurations are just a screen hanging in a sump. For intermediate aquarists, compact size and better performance might be wanted. These configurations might be a custom built acrylic unit, with very bright lighting. For advanced aquarists, compactness is usually not a concern, but strong performance and redundancy of lighting and flow is. So a dual-screen, dual-pump, triple-light configuration would be best.
Q: Where should I place the scrubber in my system?
A: Theoretically, the "best" for a reef tank is to have the scrubber above the display, so that all the pods can drain into the display unharmed. But if the goal is just to remove nitrate, phosphate and nuisance algae, then it really doesn't matter where you put it. Other things are much more important.
Q: Besides the designs like the screen-in-the-sump, the acrylic box, and the top-of-the-nano-tank, are there any other options for special situations?
A: Certainly: Circular, horizontal, trough, Dual-screens, hang-on-wall, recirculating, and display-light powered.
Scrubber Lighting:
Q: What kind of light do I need?
A: Experience has shown that at least a 23 Watt Compact Fluorescent (CFL) floodlight, of "plant grow" color (2700K or 3000K) works best. One on each side of the screen. And note that 23W is "at least". These CFL lights have also shown to only last about three months before their power drops off (even though they "look" fine). T5HO 3000K has also shown tremendous growth; they are more difficult to design and build, however.
Q: What if I can't put a light on both sides?
A: Then double the screen size, and double the lights on the one side. Doubling the screen size without doubling the lighting, however, does no good.
Q: Can I use LEDs for lighting the screen?
A: LEDs are still being experimented with, for use on algae (which is different from using them for a display.) Thus they are not recommended if you absolutely want results. If, however, results are not as important as "experimenting" is, then by all means try LEDs, but make sure they are as powerful as possible. A few watts here and there will not be enough. You want "reds" (670nm) and "blues" (420nm), in the high-power variety. Several horticulture and hydroponics sites sell ready-to-use LED panels and strips, which may work.
Q: Can I use solar power on the screen?
A: Yes, if you have many days of sun throughout the year. The screen will, in effect, be one-sided, so you'll need twice the size. Might be a good idea to still have a regular secondary or portable scrubber inside your house, in case of long lasting storms or winter days. You may also consider using a reflector (like aluminum or mylar) on the backside of the solar scrubber, and using lights on it for nights and/or backup.
Q: Are halides too strong for a scrubber screen?
A: They are not too strong, but the results that have been observed on halide scrubbers have not been fantastic. Also they are very hot. So it's currently advisable to not use halides.
Q: How long do I wait before replacing the bulbs?
A: CFL bulbs should be replaced every 3 months. T5/PC bulbs every 6 months.
Q: How near do the lights need to be to the screen?
A: Within 4 inches (10cm) from the middle of the screen. If you cannot get the light nearer that 6 inches (15cm), then do some reconfiguration. Don't build a scrubber at all if you can't get the light to within 6 inches (15cm).
Q: What's the best wattage/power bulb to use?
A: The most that you can afford and/or deal with. You cannot have too much light. The more powerful the light, the faster your nitrate, phosphate, and nuisance algae will be reduced, and the lower they will stay. The bare minimum for any setup is a 23W CFL Floodlight, 2700K or 3000K.

 

[santamonica]

Part 4 of 11:
Q: I have some extra lights I was using for my display; can I use those?
A: Only if they are 6500K or less. 10K is problematic. 14K will not work at all. And the power on each bulb still needs to be at least 23W, on each side of the screen.
Q: What's the best bulb color or spectrum?
A: The very best is the "plant grow" spectrum. These bulbs looks "pink", and don't seem bright at all. But for a given wattage, they grow algae the best.
Q: How long should I leave the lights on for?
A: 18 hours. 20 hours max. Never run the lights 24/7, because the algae will stop growing near the light. Algae needs rest.
Q: I see many times that people try a certain bulb, and then they are told it's not the right one. What bulbs should I not use?
A: Don't use incandescent, blue or green "plant lights", desk lamps, reading lights, heat lamps, halogens, black lights, colored lights, actinics, bug lights, or fog lights. Do use CFL floodlights or T5HO bulbs, in 2700K, 3000K, or "grow" (pink) spectrums.
Scrubber Flow:
Q: How much flow do I need on the screen?
A: 35 U.S. gallons per hour (gph) (133 lph) for every inch (2.5cm) of width of the screen. Thus a screen one inch wide would need 35 gph, and a screen two inches wide would need 70 gph, etc.
Q: Will the flowing water put bubbles into my tank?
A: If the screen is built/adjusted properly so that the water flows smoothly down the screen, and if the screen is in the water at the bottom (so that the water does not "drop off the bottom"), then no bubbles should be added.
Scrubber Materials:
Q: What's the best material to make the screen out of?
A: The overall best material is "Plastic canvas", which can be found at any craft/sewing store, and online at hundreds of places. It's strong, stiff, and does not wear out. It is not the best performing material, however. "Rug Canvas" is the best performing material, because it's made of fiber that algae really sticks well to. But it is flimsy, and it frays at the edges, so it needs more care and framing. Also, it does not last forever, and will need replacing.
Q: Can I use window screen?
A: No. That type of screen sometimes has chemicals to reduce mildew. Plus, it's too flimsy, and it cuts/breaks too easily.
Scrubber Results:
Q: What can I do to get the best results from my scrubber?
A: When building it, use the highest power bulbs that you can, and put them as close to the middle of the screen as you can. When operating, clean the screen weekly, no matter what, using freshwater or tap water in your sink. Clean sooner if the algae is dark brown or black.
Q: I heard that you have to watch out for getting an "oil slick" on your screen.
A: "Oil slicks", or very dark or black algae, usually happen when a scrubber is first set up on a tank with very high nutrients. This algae does not get thick, and it doesn't even look like algae. The problem is when the person thinks that his screen is "just not growing yet", and he leaves the screen alone (not cleaning it) in order to "give it more time to grow. BIG MISTAKE. What actually is happening is that this particular type of algae is already fully-grown on the screen. And since it's very dark, the outer layers block ALL the light from the inner layers, even though the algae is only 1/4 inch (6mm) thick). So the inner layers die and go back into the water, adding nutrients back. So, the person leaves the screen alone even longer "to give it even more time to grow", but the new outer layers once again kill the inner layers. The screen never gets "thick" like the person wants, and so the person never cleans it. Nutrient levels stay the same in the tank, and the person feels that the scrubber is not working at all. The solution is to clean any and all dark/thin algae off as soon as it grows, EVEN IF it's just two days old. This will bring nutrients down, and after a few weeks of doing this, green hair algae will start to grow. At this point you can switch to normal weekly cleaning.

 

[santamonica]

Part 5 of 11:
Q: All I seem to get on my screen is brown slime. Must I have green hair algae?
A: No. All algae filters the same. They are just different types depending on how high your nutrients are in your water, and how strong your light is. Continue weekly cleanings (twice a week if the algae is dark brown or black), and eventually you will get green. If not, try stronger light.
Q: I'm not getting good flow out of the slot, especially when the screen fills up with algae. What can I do?
A: Try making cross-cuts in the slot, every inch (2.5cm) or so. The cross-cuts will reach out past the algae, and will allow water to still flow when algae has blocked the regular part of the slot. Also, of course, you could just widen the slot.
Q: My scrubber smells. Is this normal?
A: No. It means your water flow is too low, which lets some of the algae touch the air. Increase your flow, or widen the slot.
Q: I'm getting cyano on my screen. Is this good?
A: No. It means your light is too weak or too far away. Regular algae (green, slime, brown) should be the only thing growing.
Scrubber Comparisons:
Q: How is a scrubber different from a skimmer?
A: Scrubbers remove Inorganic Nitrate, Inorganic Phosphate, ammonia, metals and CO2 from the water. (Inorganic Nitrate and Inorganic Phosphate are what cause nuisance algae to grow on your rocks and glass, and are what you measure with your test kits.) Skimmers remove Organics (food) from the water. Both scrubbers and skimmers, however, add oxygen to the water.
Q: How does a scrubber compare to a refugium with macros?
A: Scrubbers are different from a fuge in so many ways:
o With a scrubber, there is very little water standing in the way of the light. Also, the light is (or should be) very close to the scrubber... 4 inches (10cm) or less. The power of light varies with the square of the distance, so going from 8" to 4" actually gives you 4X the power, not 2X. And the nutrient removal power of algae and macro is proportional to the power of the light, because it's the photosynthesis that is doing the processing.
o Rapid flow across the algae give more delivery of nutrients, compared to the slow moving water in a fuge.
o The turbulence of water moving over the sections of algae help remove the boundary layer of water around the algae. This boundary layer slows the transfer of metabolites in and out of the algae. There is no turbulence in a fuge (if there were, you'd have bubbles).
o Traps no waste/food like a refugium or DSB does; waste/food flows right past the screen.
o Does not release strands into display, like chaeto.
o Does not go sexual, like caulerpa can.
o Is 1/10 to 1/4 the physical size, for the same processing power.
o Weighs nothing (holds no water), so it can built into a box and placed on furniture.
o Cools the water. And if a fan is used, it REALLY cools the water.
o Does not ever produce hydrogen sulfide (rotten eggs), like DSBs or denitrators can.
o Can be set on top of the tank, so pods drain right into tank.
o Is free (you build it).
o Is portable, if in a container.
o Can run two or three, for backup or extra filtering, in the same space as one fuge.
Q: How does a scrubber compare to a denitrator?
A: A denitrator removes nitrate. A scrubber removes nitrate, nitrite, ammonia, phosphate, CO2 and metals. Also, a scrubber cannot harm a tank, whereas some denitrators, if adjusted improperly or if they malfunction, can put harmful chemicals into the water.
Q: How does a scrubber compare to GFO (granular ferric oxide) phosphate removers like RowaPhos and PhosBan?
A: GFO's do remove phosphate, although they may lower the pH while doing it. And they are expensive. Scrubbers remove phosphate, as well as nitrate, nitrite, ammonia, CO2 and metals, and do so while increasing the pH. And once built and installed, a scrubber does not need to be "refilled". Also, if GFO bag or canister spills, or if you accidentally drop some in, the GFO will go everywhere throughout your sump/pumps/tank. If you drop algae in the tank, it's no different from algae that's already in the tank.
Q: How does a scrubber compare to a Remote DSB (RDSB)?
A: RDSB's removes Ammonia, Nitrite and Nitrate. Scrubbers remove the same, in addition to phosphate, metals and CO2. RDSB's, however, just like regular DBS's, tend to store phosphate in the sand during high-nutrient times. It then releases the phosphate during low-nutrient times. Scrubbers don't "store" phosphate; the phosphate is "in" the algae that grows, and it is then removed during weekly cleaning.

 

[santamonica]

Part 6 of 11:
Q: How does a scrubber compare to vodka (carbon) dosing?
A: Both remove nitrate and phosphate. Vodka, however, requires a skimmer to operate (to remove the bacteria that grows), and this skimmer thus also removes food from the water. Vodka also reduces the oxygen in the water (bacteria use it). Scrubbers don't require (and work best without) a skimmer, and they add oxygen to the water. Lastly is the safety issue of vodka: If you carelessly pour it from a bottle, and pour "just a few ounces too much", your entire tank will be dead in a few hours. With a scrubber, there is nothing that can happen which would cause such a situation.
Scrubber Applications:
Q: Can I put a scrubber on my nano?
A: Yes, you can make/put a scrubber on any tank. There are two types of nano's: Those with a hatch on the top that let you get to the filter area, and those where there is no hatch (like Aquapods) where the whole lid opens up as one unit. Aquapod types are the hardest to add your own scrubber to; however the hatch-on-top types are the easiest.
Q: Have scrubbers been used for breeder or retail tanks?
A: They are being tested now.
Scrubber Advanced Topics:
Q: What exactly does a scrubber do to my water?
A: It takes ammonia, nitrite, nitrate, phosphate, metals (like copper), and CO2 out of the water. It puts oxygen into the water. It also cools the water. And if you put a fan on it, it REALLY cools the water. Increased evaporation, of course, will also occur. Copepods are added to the water. Iron and Iodine are removed from the water, but they are of lesser importance, and are removed to a lesser degree, than the above items. Alkalinity may in some cases be slightly decreased, because of algae's slight use of bicarbonate to get CO2. Water clarity is sometimes improved, because of the increased oxygen (similar to ozone).
Q: What if there is a power outage? Will my scrubber die?
A: In most cases you will loose your tank before you loose your scrubber. With no power (and thus no flow, and no lights shining on the algae), the outer layer of algae hardens and keeps the inside layers wet. Six hours should not be a problem.
Q: I've heard you have to "pulse" or "surge" the water to get best results.
A: This is not proven yet. Most scrubbers use a constant flow, and have great results.
Q: What type of algae is best to grow?
A: You don't have much choice; algae will grow based on lighting and nutrients, and will even change as your nitrates and phosphates drop. All algae consume nitrate and phosphate, so it really doesn't matter what type algae it is.
Q: Can a scrubber "crash"?
A: No. There is no situation in which a scrubber can "fall to pieces", dissolve, disintegrate, or otherwise destroy itself and the tank that it's connected to. The worse that can happen to your tank is that the scrubber light burns out and stays out for 2 or more days, in which case the algae will slowly start dying over the next couple weeks.
Q: What kind of pods does a scrubber grow?
A: Supposedly copepods, amphipods, mini-stars, etc. However there have only been actual reports of copepods.
Q: How long does it take to get the real "red/brown" turf?
A: Current experience has shown that unless you start with a pre-grown turf screen, it will never start growing on it's own. All algae is good, however, no matter what color or texture it is. Real red/brown turf just filters the most for a small size, that's all. But it's not like other algae take up a lot of space.

 

[santamonica]

Part 7 of 11:
Q: I've heard that scrubbers evaporate a lot of water.
A: The typical DIY scrubber in a sump will evaporate and cool the water. If you put a fan on it, it will REALLY evaporate and cool the water. Some people want this, others don't. If you don't, then enclose your scrubber in acrylic or plastic so that no air gets in. (And be sure so cover all electrical and bulb connections with aquarium safe silicon.)
Q: My scrubber has gotten rid of my green and brown nuisance algae in my display, but the dark purple cyano remains. Will it go away too?
A: Cyano is the last of the things to disappear, because it can make its own nitrogen and thus does not need ammonia/nitrate/nitrate to do it. So it may last a while, but if you keep nutrients low enough for long enough, it too will fade. However, it may be covered by coralline before this happens.
Q: Since scrubbers don't remove food from the water like skimmers do, won't the DOC (dissolved organic carbon) build up and cause problems?
A: No. You need to realize that DOC is food also, it's just microscopically small food, mostly eaten by bacteria, and by some corals. So the DOC reaches a level and stays there, since it's being kept in check by the bacteria. And the bacteria themselves are food for corals. But also you need to know that recent research has shown that skimmers themselves actually don't remove (much) DOC as previously thought. Skimmers are mostly removing POC (particulate organic carbon), i.e. pieces of food. That's why they are called "protein skimmers", because food is protein.
Q: I'm getting micro-bubbles in my tank; how do I stop this?
A: Bubbles are usually caused by having the screen above the waterline, so that the water falls off the screen into the water. This is solved by making sure the screen goes into the water an inch or so. Another possible cause is that your slot in the pipe is too narrow, causing the water to be forced out. Try widening the slot (if your pump has enough flow.) If bubbles are still present, make an "under-over-under" pathway for water to go after the scrubber. Don't use foam blocks, however, since they catch the pods and other food that you want floating around for the corals and fish to eat.
Q: Sometimes my scrubber sometimes sprays sideways and gets things wet. How do I stop this?
A: If your screen normally flows properly, the sideways spraying is caused by not cleaning the part where the screen inserts into the pipe. Algae grows right up into the slot, causing the spraying. The solution is to clean up into the slot when cleaning, or (better) remove the screen from the slot entirely when cleaning it. To prevent it entirely, you can make a little "light shield" and attach it to the side of the pipe, in order to shade the top of the screen from light. You can also just clean more off the top of the screen, so that there is a 1/2" empty area with no algae at all just below the slot.
Q: Are two screen better than one?
A: Two screens allow you to clean one, while leaving the other operating. This prevents nutrient "spikes" from occurring in your tank, because when you clean a screen you sometimes have very little algae left on it for filtering. Thus the other screen takes over. The trick with twin screens is to make each one big enough (with enough light for each one) so that each one can do all the filtering by itself.
Q: Are multiple lights better than one?
A: Aside from just being brighter (which is always better), multiple bulbs give you a backup in case one burns out. It also give more even coverage of the screen from edge to edge. You can't have too much light.
Q: I really want lots of pods; what can I do?
A: First make sure you have no (not one) mechanical filter in your system. This includes a skimmer, foam pads, and floss. All food and pods should be allowed to circulate forever. Next, before you take your screen out for cleaning, put it into your tank and swirl it around. This will release many pods into the tank (don't shake hard enough to remove algae, though). After doing this, do your regular FW cleaning in your sink.
Q: What is the single most important thing I need to know or remember about scrubbers?
A: That scrubbers remove Ammonia, Nitrite, Inorganic Nitrate, Inorganic Phosphate, metals, and CO2. Skimmers don't.
Q: If I put a scrubber in my sump, will algae start growing all over the sump?
A: No. The lights of a scrubber are very near and pointed at the scrubber screen (4" or less) for a reason: Light is only powerful when it is near. Thus, the bulbs are too far from the other parts of the sump to cause algae growth.

 

[santamonica]

Part 8 of 11:
Q: I'm getting a thin tar-looking growth on the screen, but it won't grow anymore.
A: What you have is the type of algae that grows when nutrients are extremely high. After a few cleanings, when the nutrients come down, the color will lighten up to some balance point where it will stay. This type of dark algae does not grow thick at all. It never gets more than 1/4" (6mm) or so. And worse, since it's so dark, it blocks all light from reaching the bottom layers, thus causing those layers to die and release nitrate and phosphate back into the water. The solution is to clean all dark brown/black algae within a few days, and don't even wait until the end of the week. Basically, if you cannot see your screen because of the black algae, then light is not reaching the bottom layers and it needs to be cleaned. You'll only have to do this a few times before the nutrients come down and the algae color lightens up; then you can go back to weekly cleanings.
Q: I'm worried about my screen/pipe clogging and causing an overflow; what can I do?
A: Screens never clog from debris/junk flowing in the water; they only get sections of "reduced" water flow, where the algae grows up into the slot in the pipe. The ways you can prevent this is (1) Install a "light shield" along the length of the pipe; a strip of plastic that blocks light from reaching the top part of the screen near the slot. (2) When cleaning the screen, clean the top 1/2" (12mm) of the screen extra well, and leave no algae behind. This will cause the algae to take longer than a week to grow into the slot, by which time you will be doing another cleaning. However if you would feel safer with a backup, then just put an "L" on the end of the pipe, pointed up a few inches. If the screen ever somehow got plugged up, the water would just get pushed out and up the "L", where it would flow down.
Q: Will scrubbers work with other filter devices, like skimmers, vodka, reactors, denitrators, pads, zeo, etc?
A: Scrubbers will works with any device/setup. One exception might be xenia; if you want to keep your xenia, you'll probably need to start feeding much much more after you start using a scrubber. Or you could try adding iodine. If you don't feed more (much more), the xenia will probably fade.
Q: I heard there is someplace you can buy a turf screen already grown.
A: If you need instant results, and you can't wait a few weeks to grow your own algae, then you can buy pre-grown turf screens from Inland Aquatics. But turf screens must be cleaned often, so that green hair does not grow over it and shade it.
Q: Why do I want to clean my screens with freshwater? Don't I want to keep as many pods as possible?
A: Don't worry, you'll have endless pods. Microscopic pods grow so fast in the algae (by the millions each day), that they start eating the layers underneath. This releases nitrate and phosphate back into the water. Sometimes if the algae is not too thick, the pods will eat big holes in the algae that you'll see on the screen. This is not good. By cleaning the screen weekly in freshwater in the sink, the pods will be removed, and excess nitrate and phosphate will not be released into the tank. But the next day there will be millions more.
Q: In a typical emergency, like a big fish dying overnight, or a huge amount of food being dumped in that you don't know about, isn't it better to have a skimmer than a scrubber?
A: Well, an "emergency" is best handled with everything that you own; Skimmers, scrubbers, and anything else will only help for the next five or ten hours that follow. But since most of us don't design our tanks with emergencies as the prime focus, we need to choose equipment based on what has the greatest impact by itself. A large dead fish, or a ton of food, doesn't cause a problem immediately. It's only a few hours later when bacteria have started converting them to Ammonia/Ammonium, that you have a problem (since Ammonia/Ammonium are poison in your tank). Ammonia/Ammonium are the favorite food of algae, so if you have a scrubber, the Ammonia/Ammonium is removed as it develops. If you only have a skimmer, however, you are in trouble because a skimmer does not remove any Ammonia/Ammonium. None. Not even a little.

 

[santamonica]

Part 9 of 11:
So in the case of the large dying fish, if you only have a skimmer, then your entire tank will die because there is nothing to remove the Ammonia/Ammonium. In the case of excess food, the skimmer will indeed remove a lot of it (that's what skimmers do, remove food), so there will be less food to rot into Ammonia/Ammonium. But the question is, will the Ammonia/Ammonium that remains still be enough to kill things. At least with a scrubber, all the excess food will stay in the water (to be eaten by fish/corals), and the Ammonia/Ammonium that develops will be removed. With excess food, having both a skimmer and scrubber together works the best. But in the case of a dead fish, have both is of no benefit; only the scrubber performs a useful function. All this is assuming, of course, that you are not around to do waterchanges.
Q: I have lots of green hair algae all over my rocks, but my nitrate and phosphate always measure "zero" when I test it. How can this be? Are my tests bad?
A: No. Your tests are fine. What you are seeing is the power of algae at removing Inorganic Nitrate and Inorganic Phosphate (which is what test kits read.) You have so much algae in your display that all the nitrate and phosphate is eaten before your test kits can read it. Basically, you already have a scrubber; it's just in the wrong place (all over your rocks).
Q: Is there a screen shape that is the most powerful?
A: Yes. Screens that are very wide, but not very tall, are the most powerful. This is because the lower part of a screen is not as effective as the upper part, since the water flowing over the lower part has already been filtered by the upper part. So a screen that is not tall (no lower part) makes up for it by being wider. In effect, the whole screen becomes the "upper part". Wide screens, however, require more flow because they have longer slots. (Note: Other things have far more effects on performance, such as light, flow, and weekly cleaning.)
Q: Is there a screen thickness that is most powerful?
A: The thicker, the better. This gives the "roots" of the algae more to grab onto, so it all won't come off when you clean it. Two layers, or even three layers of screen will do this for you.
Q: I bought a pre-grown real-turf screen; how do I take care of it?
A: Real red/brown turf is a little different from other algae. Since it's so thick, it packs all the nutrients into a very tight space. Thus is does not need to be cleaned off the screen as often. Also, when it is cleaned, a razor blade is usually necessary to scrape it off. Scraping a real turf screen is usually done about one time per month. However, green hair algae and slime will cover the turf quickly, and pods will eat it quickly, so you still need to "clean" the turf in your sink with freshwater. Scrub the turf under the water like you are shampooing hair. The green hair and slime will come off, but the turf will remain. This is very quick and easy. Then, every fourth week, do a full scraping with a razor.
Q: I travel quite a bit, and sometimes can't work on my tank for weeks at a time. Can I still use a scrubber?
A: The easy and safe answer, is no. However, depending on how much you want to learn, and how much space and time and electricity you want to devote to your scrubber, it possible to design and build a very oversize scrubber that will last for an entire month between cleanings. The reason a standard-sized scrubber needs weekly cleanings is because the new algae growth covers up the old growth, causing the old growth to be shaded, which kills it. Weekly cleaning removes the old growth before this happens. A very oversized scrubber, however, would only build up a very thin layer of algae across a very large area (same amount of algae, spread over a larger screen). Since this layer would not be thick enough to block the light, it would continue to stay alive until you returned home. The bigger the screen, the longer it can go. The standard screen size of one square inch (6.25 square cm) per U.S. Gallon (3.8L) goes one week; so two times area this would go two weeks; three times for three weeks, etc. But the lighting must also be doubled or tripled. You can't increase the screen size without increasing the lighting across the screen too. Thus you not only have to be able to accommodate the large size, you also have to pay for the increased electricity, every week.

 

[santamonica]

Part 10 of 11:
Q: I've seen pictures of scrubbers that float on the water, in the sump. This seems like an easy solution. Are these recommended?
A: Floating screens have potential, but there have been no reports of any successful one in an aquarium. For one thing, they are one-sided, which means they must be double-sized. But that is quite a bit of surface area, especially in a sump with equipment. It would take a bathtub-sized sump for most aquariums. Also, getting flow evenly across the whole screen might be a challenge, and thus it may need several outlets pointing at different parts of the screen. One big advantage, however, is that if the flow (or electricity) ever went off, the screen would not die since it would always be in the water.
Q: Should I continue to run mechanical filters after I install a scrubber?
A: No. Mechanical filters such as foam pads, floss and filtersocks trap food and cause it to rot into nitrate and phosphate. Even if you planned on cleaning them daily, why feed the tank at all, if you are just going to trap the food and remove it? And yes, fish waste is food too. Other items can also act as mechanical filters, such as carbon and phosphate reactors/canisters, and bio balls. Large food items (like mysis) get stuck in them and rot. Carbon is not needed with a scrubber (unless it's needed for something else, like removing medication); phosphate-removal is handled by the scrubber, as is the nitrification function of the bio media/balls (and the live rock and sand, if you have them). Basically, food such as mysis should be able to flow throughout your entire system for hours and hours, without getting stuck, so that your fish and corals can eventually eat it. All the rest will be taken care of by the scrubber.
Q: Some people have surge devices on their scrubbers. Is this better?
A: It is not known yet. The idea is, the air in-between the surges will remove the boundary-layer of water around the algae, allowing it to transfer nutrients better. But so far, scrubbers with surges have not shown better results than those without. Plus, a surge reduces the amount of time that the water is being filtered.
Q: If I want extra filtering, can I just increase the size of my screen?
A: Only if you increase the lighting too. Extra screen does no good if it's farther than 6 inches (15cm) from the light; and 4 inches (10cm) should really be the maximum.
Miscellaneous:
Q: If scrubbers work so well, why haven't I heard of them before, and why haven't people been building them before now?
A: Because the inventor of the scrubber had a patent on his design, yet he did not sell the scrubbers to the public; and he did not allow others to sell them either. So people thought that since his design was the only one that was patented, then it must be the only design that worked. As you can see, his is not the only design that works.
Q: What are the drawbacks to scrubbers?
A: You have to build them, they require weekly cleaning, they give off a lot of light (unless you enclose them), and they cause lots of cooling/evaporation (unless you enclose them). Any other drawback that you may have heard is either old information (previous to June 2008), or the scrubber in question was built incorrectly or is being run incorrectly.
Q: Why have scrubbers caused so much anger by so many people?
A: These people are angry because:
1. They are employed by, or they are a relative/friend/spouse of someone who is employed by, a manufacturer/distributor/retailer of skimmers. There are over 3,000 stores in the U.S. alone that sell skimmers, with several people working at each one. That's a lot of people to post anti-scrubber comments online.
2. They have a lot of money invested in their skimmer and other equipment. So they feel ripped off to find that a cheaper piece of equipment can do a better job of removing nutrients. It makes them look unprepared.
3. They were around in the 1980's and 1990's when scrubbers were built and operated incorrectly. Scrubbers back then caused yellowing. Scrubbers today don't. But these people have not used a modern scrubber, so they think all scrubbers still operate the same.
4. They don't understand how scrubbers works (and they are not going to learn.) They think that skimmers remove Ammonia, Nitrite, Inorganic Nitrate, Inorganic Phosphate (i.e., all the bad stuff). But skimmers don't. Not even a little. Scrubbers do.
5. Since they already have a setup that works properly, they have no reason to expend the time and energy to change. This is understandable.

 

[santamonica]

Part 11 of 11:
Q: I've heard that these "waterfall" types of scrubbers are not real "ATS" scrubbers.
A: "Scrubbers" and "ATS scrubbers" are anything that move water over a lit surface, for the purpose of growing algae. What the "ATS" confusion is related to, is that one of the original patented scrubber designs in the 1980's uses a dumping design that dumps water onto a horizontal screen, and the owner of this patent also owns the trademark "ATS" name (as well as other scrubber designs). So, people confuse the word "ATS" with that particular dumping design, only because it was the most popular one.
Q: Will a scrubber help me to grow coralline?
A: Absolutely. The main reason most tanks don't grow coralline is because their phosphate levels are too high. Anything over .03 is going to slow down or stop coralline. Since a scrubber will reduce the phosphate to less than .03, it will allow the coralline to flourish.
Q: Some experienced aquarists told me that a scrubber might make the water cloudy or yellow.
A: Cloudiness is caused by not cleaning the screen weekly (which they did not do in the 1980's and 1990's). When not cleaned, the underlying layers of algae get covered up and shaded by the newer outer layers, and thus the underlying layers die and get washed back into the water, causing the cloudiness. Yellowing is caused by cleaning the algae without removing the screen first. You are supposed to remove the screen and clean it in the sink under freshwater. If you clean the screen when it's still in the system/sump/bucket, the broken algae strands empty into the water, and yellow it.