sump return questions

[dive girl]

I have no idea why I just don't get it!

I've searched on here and on search engines and looked many diy projects but I can't understand the final chamber of the sump.
I've built my own sump/refugium using a 20 gallon glass tank. It runs under my 29 gallon DT. I use an overflow box.
I have plumbed it with a ball joint on the overflow (so if I need to stop it for some reason, I can without breaking the suction), a ball joint on the return along with a one-way valve, and a return line going back into the sump so that if I need to slow down the flow I can without putting a strain on my pump (Rio 1400).
Here's what I'm just not getting:
It seems like I am constantly having to make small adjustments (at least once a day!) to one of the ball joints to keep the flow at the same rate of return as I have coming in from the overflow. Does everyone have to do this? If not why? It is a huge pain to have to do this so often! I'm doing something wrong, but I'm not sure what.
Why is evaporation only seen in the last chamber of a sump?

 

[dive girl]

My biggest worry is not that the overflow will cause a flood if the power goes out (I've made sure that there is enough room in my sump to handle the excess water) but if the return pumps more water into the tank than my overflow can keep up with causing my DT to overflow.

 

[slade1274]

Your overflow line to the sump should be wide open and the return pump is the control. The overflow can only return as much water is the pump puts in the tank to fill it "past" the overflow.

 

[dive girl]

Oh, so the water level in the DT is constantly changing between when the overflow fills and when the waterline is too low to add anymore?
If that's right, I think I'm understanding it. I was trying to keep the flow in the same as the flow out so that the level didn't change at all.

 

[slade1274]

What kind of overflow box are you using? The level in the DT shouldn't change... well maybe 1/2" max depending on flow rate from the return pump. The DT level is determined by the height of the overflow box. Once return pump puts water back into the DT, the level rises to where it can overflow into the box and return to the sump. The sump level will change due to evap, but all else should remain constant as long as you control the retun put to not overdrive the ability of the overflow....

 

[scsinet]

The DT is always full, the level doesn't change by any appreciable amount.
The return pump keeps your DT full at all times. The water spills over into the overflow at the rate that the pump pumps it (returns it) into the DT. Think of a water glass sitting in the sink. Turn on the sink, and water fills the glass and spills over. How fast the water spills over into the sink depends on how fast you've got the water running, and the amount that spills over exactly equals the amount that's being introduced by the faucet.
What you are doing is a common newbie mistake (one I made myself), trying to balance the flow. You fear flooding, but in fact what you are trying to do is in fact what's going to make you flood.
Open the valve from your overflow all the way. The overflow will only drain water at the exact rate the return pump is returning it (as long as the return pump does not exceed the overflow's design capacity). Regulate your flow with the ball valve on the return pump ONLY. Your plumbing is set up exactly correctly, all you need to do is change the way you are trying to control the flow.

 

[natclanwy]

Need more info on your Overflow box what size is it? A rio 1400 is extremely small for a return pump and I would guess that you are looking at a flood in the near future unless you have an uncommonly smalll overflow box. Also how much verticle plumbing do you have (distance from the sump to the DT)? The return should be able to send water back to the DT fast enough so that when it drains it has enough velocity to carry any air bubbles out of the U-tube, if not they will slowly accumulate and slow the overflow box down and eventually the return pump will return more water than is draining back to the sump causing the DT to overflow.
You need to open the valve on the overflow drain 100% and then use the ball valve on the line from the pump to the DT to slow the flow rate down if it is sending too much water which is very unlikely given the size of the return pump.

 

[dive girl]

Thanks so much for the answers.
The plumbing is 46" from the sump to the DT. The overflow box is 5.5" long x 3.75" wide and 6" deep.
If the 1400 isn't strong enough, what would you recommend for a pump?

 

[natclanwy]

What size is the drain on the overflow box?

 

[wattsupdoc]

Depending on the overflow box, you may have a problem later as mentioned. If it uses a pump to keep the box primed, just a little pump, usually an aqualifter is used, your OK. Also adding one of those to a "U" tube style (what I think you have) will solve this problem. Post some pics of your set up and we can further tell what you have. The Rio 1400, only has a flow of 240gph @4 foot. The smallest that I am familiar with OF box is 600gph...but that doesn't mean yours isn't smaller. A Rio 2500 would be more in line with a 600 GPH OF box. Or better still, a mag 7.
Your volume changes in the return pump compartment because that is the only compartment(including your DT) that CAN fluctuate with evaporation. All other compartments the level is controlled by baffles etc. Setting up an auto top off is beneficial with a sump, not NECESSARY, but very helpful.

 

[dive girl]

The drain on the box is 1" but the input PVC pipe into my sump is 3/4" (I don't know if that changes how you measure the flow or not).
Thanks. I was thinking about getting an ATO once I was able to get my sump squared away.

 

[natclanwy]

Your pump is way too small, with a 1" drain I would guess your overflow is rated for about 600gph. HOB overflows are very finicky about the size of return pump you use, you need one that is rated for 70-100% of the overflows rating after headloss is subtracted in order to reliably maintain the syphon. Your rio is only returning about 200g after headloss or about 33% of your overflows rating. I would reccomend getting a quietone 3000, or a Mag 7 as a return pump and increase the size of your drain and return lines to 1".

 

[dive girl]

Thanks! I'll look into increasing my pump today.

 

[dive girl]

Okay. I've opened up the line from my overflow box all the way as well as the return line from the sump to the DT. The pump is able to pump more water than the overflow can drain (no bubbles). This is probably because I have 3/4" (inner diameter) plumbing instead of 1".
I've made sure that I have enough room for any excess water to flow into the sump making sure that I don't have an overflow in my sump.
Is there anyway to guarentee that I don't have a flood in my DT? I'm going to look into an aqualifter to make sure that my overflow always stays primed and bubble-free. But what if for some reason my pump starts to overwork my overflow if I'm not home?? The DT is going to flood; is there anyway to prevent that?

 

[natclanwy]

I would skip the aqualifter they are notoriously unreliable, unless you have a CPR style overflow than I would definetly invest in one since a CPR overflow will not stay primed on its own. If you are running a U-tube style overflow there is no need for the aqualifter, as long as you are running the correct size pump the bubbles should travel through the U-tube without stopping. If they collect at the top your flow rate isn't fast enough.
Which pump did you upgrade to? As far as the pump sending water to the DT faster than the overflow can drain it, this is the reason I don't recommend buying a pump that is rated for more than the overflow is rated for. I don't like the idea of relying on a valve to control the flow rate because if it is not adjusted correctly it can overflow the DT and it could take several hours before it does overflow. As long as you keep up on your maintence of the pump and the overflow they are very reliable, I have had mine running continuosly for 4 years and never lost the syphon. I have had a couple very small floods, less than a gallon of water but both times were my fault and I was standing right there. Both were cause by the pump intake getting clogged with chaeto which slowed the flowrate allowing bubbles to accumulate at the top of the u-tube. When I unclogged the pump I thought the bubbles would clear on there own, I was wrong the pump just barely overflowed the DT before I could get it unplugged.

 

[wattsupdoc]

I run an aqualifter to prime my DIY U rube between my sump and my fuge. For almost a year now with no problems. Also, I run one to feed my calcium reactor, no problems, additionally I use one to run my ATO....no problems. So notoriously unreliable? I don't think to. Keeping them from getting plugged my crud and critters, yes.
You flow rate through the Of wont degrade with time. Not if you do proper maintenance. Also, I never had a flood that occurred while I was gone because of the level "creeping" up in the DT. Not over extended periods of time anyways. The level WILL creep up, but it should only take several minutes to do so. So adjusting the BV is fine. Just watch it if you have it closely matching your OF box. There is no problem AT ALL oversizing your return pump.

 

[dive girl]

So, I see it's kind of like everything else in this hobby... what works for some doesn't necessarily work for others and what works for others doesn't necessarily work for some??
I'll keep a close eye on my u-tube to make sure that I'm not getting any bubbles, I'm not currently.
I haven't upgraded my pump yet because none of the LFS carried either model of pump you recommended. My original pump (the Rio) is overworking the overflow.
Could starting to run a sump cause a mini-cycle? Ever since I started running it my ammonia and nitrites have been at 0.25. All of my water parameters were in-line with what they should have be before I added the sump. My pH has been hovering around 7.8-8.0 as well. My alkalinity (actually a little high right now because I added a buffer) is fine as is my calcium (420). I thought it might be a drop in Co2 in the house with the heater running more and the windows being closed so I angled all the powerheads up towards the surface and leave a window in the room with the tank open during the day.
Any thoughts?
Heck, for something that should help my reef, this has been one pain in the butt!

 

[natclanwy]

I run an aqualifter to prime my DIY U rube between my sump and my fuge. For almost a year now with no problems. Also, I run one to feed my calcium reactor, no problems, additionally I use one to run my ATO....no problems. So notoriously unreliable? I don't think to. Keeping them from getting plugged my crud and critters, yes.
Do a search on some of the other boards for aqualifter and you will find hundreds of threads about aqualifters failing, CPR style overflows seem to have fallen out of popularity compared to 3 or 4 years ago so you don't hear as much about them as you used to. It used to be the general consensus if you bought one it was recommended that you buy two because they would fail so often maybe they have improved their quality in the last few years, but even if they don't fail mechanically getting plugged with crud and critters still qualifies as a failure which decreases their reliability. Mine never failed mechanically either but I constantly had calcium buildup or a piece of algae or other debris plug up the pump and using it with a CPR overflow is a dangerous combination since the CPR overflow cannot evacuate the bubbles on its own very well.
You can have an overflow hours after you set the valve on your return pump, take this hypothetical situation. If you are returning a half gallon of water to your DT more every hour than your overflow is capable of draining and you have an extra capacity of 4 gallons in your DT it will take 8hrs to overflow the DT. If you are watching your tank you will probably catch it in time and correct the situation but if you adjust it in the evening and then go to bed you may not.
On my old tank setup my return pump returned the same amount of water that my overflow could drain actually a few more gallon per hour. The first pump I had, had issues with restarting after a power failure so I got another on warranty after I installed the new pump I noticed my DT level increasing over several days. Three or four times I looked at it and unplugged the pump and looked for the problem when I plugged the pump back in the level would go back to normal but a few days later it would be back up to the trim ring on the tank less than a half inch from overflowing the DT it took me a while to figure it out but the new pump was returning more water than the overflow could handle, I was able to fix it by shorting the length of hose I had on the overflow and straightening out the bends but if the DT would have rose in level over few hours rather than days I probably would have had a flood.

 

[dive girl]

Thanks for the warnings. I'll keep a close eye on everything. I took yesterday off work and spent it changing some things on my tank.

How do you figure out how much the overflow is sending compared to how much the pump is returning? Right now, the overflow valve is completely open and the return valve is completely open with the spare return closed. It seems as if both are keeping pace with each other (probably because I have the 3/4" on the overflow).
I think that I'm going to order one of the pumps you recommended today (online since I can't find them locally) so that I have it on hand.
What ATO-type of system do you have? Since I only have about 45 gallons running now, I don't seem to be losing too much water (compared to big systems) but want to do what's best for my reef and I think that is replenishing the water loss slowly over the day.

 

[wattsupdoc]

Yeah, you will also find TONS of info on sumps overflowing and skimmers flooding. Because people post when something bad goes wrong....GEEEEZ

Just because you can find posts of failure doesn't mean it's not a good product. People just don't look for help when somethings going right.. However, we still use sumps and skimmers etc. don't we?
I never said that I liked the CPR style OF. There are many other good uses for an Aqualifter. Like I mentioned, keeping the u tube bubble free would be a good thing. IT wouldn't fail if the AL failed. As long as it had been maintained, Also, the getting plugged issue can easily be avoided by simple methods of prevention and maintenance. Whenever you have any piece of equipment, you need to be aware of the maintenance issues that go along with it.
Using a ball valve you can adjust a pump that is over running a OF Box. When you use a BV to control the flow you will not get creep, not over a period of a few days. I mean your talking 1 or 2 gallons extra in the DT per day, that is a minor amount. Tweaking the BV down a tad solves this issue. Had you installed one originally, you wouldn't have had to rebuild the drain. You set it, watch it for creeping, then dial it back so it drops down just slightly. It wont creep from there. I always do and always will recommend using a pump that is slightly higher with the head loss included than the system will drain. Diverting extra flow through reactors, UV, back through the fuge, or whatever, easily justifies this. A BV solves the problem.