Continuous overflow systems??

[earlybird]

Sounds like you have a good balance. But...
The water level in the back of the overflow box should be level with the top of the pvc drain pipe. The U-tube should be below this water level and it will not break siphon. Opening the ball valve will make it louder b/c it's draining faster which helps with oxygen exchange and mechanical filtration by skimming the surface water faster removing more detritus and wase into your sump which will help with overall water quality.

 

[scotts]

I am a firm believer in "if it works don't fix it" (That bumper sticker changed my life) It does sound like you are doing it out of preferance and not function. In other words nothing is out of balance in your system, you just like to have a quiet system and that is how you can keep it quiet. Although wow that has to be tough trying to get the return flow just right. If you are just a fraction of a GPH off, over time your levels will change.

 

[kevtheiris]

ok to sum this up and keep from confusing us nooBs, lemme see if i have this right....
you CANNOT overflow your sump w/ a HOB overflow (unless theres a power outage), it will only drain water to the level of the notched in the over flow
How do you avoid this? Is there a formula somewhere that says a x" siphon will flow xGPH so you can match the return pump to the size of tubing?

 

[zman1]

The one disadvantage of running your flow through a HOB overflow at a much lower rate than it's capable of is that you can get air trapped in the U-tube. Keeping the return flow up pulls air bubbles through the U-tube. If your overflow is rated at 600 GPH and your returning 400 GPH from the sump, you may not pull all air bubbles through. Also, if your return is delivering more return water than the U-tube can handle, the extra flows over the top of the tank. Another thing that folks typically do is submerge the drain line in the sump, this also reduces the drain rate of the overflow down the drain pipe with back pressure.
As earlybird indicated on a power out condition the main tank will drop to whatever you have the fingers height set to in the main tank (see the picture he attached - the black box). Then you will have some back siphon from the return line if it is submerged in the main tank - drilling a siphon break hole to limit the amount is the best approach.
You need to calculate the flow rate you want or the max of the u-tube rating, the pump, line length vertical and horizontal, and fittings. There are good on-line calculators for figuring this head pressure/flow rate. Overflows, pumps and plumbing slow down as gunk builds up. Use unions on your pump and valves. Both ends for external pumps and only one valve and union on the output for submersibles to reduce pump return if needed. It's best to size the return pump as close as possible (including the plumbing head pressure) and use the valve to fine tune the return volume on the pump output.
To calculate how much room you need in a sump to handle the main tank drain down in a power off condition, you can do this:
There are .0043 gallons of water per cubic inch
Let's say your main tank 48" X 24"x 24". It drops 2" total in a power out condition.
48"x24"x2" = 2304 cubic inches (Volume L X W X H)
2304X.0043 = 9.9072 gallons
Your sump is a 36"X18". how many inches will your sump water rise or what would be required to accommodate the water above the normal sump water level?
36"x18" = 648 square inches (Area L X W)
2304 cubic inches (from the Main Tank) / 648 square inches = 3.556 The missing height for volume
36" X 18" X 3.556" = 2304.288 cubic inches or
2304.288 X .0043 = 9.908 Gallons
You will need 3.556 inches of sump space to accommodate the drain back water on a power out condition.
Evaporation only shows in the sump and not in the main tank - Provided sump isn't empty and the pump burned out. - no more water to return! otherwise the main tank will always be full...

 

[vorlx]

I just got done reading all of this. It's good information. I recently went through alot of this when building my own sump. I ended up throttling back my pump with a ball valve since its gph capability is higher than my overflow's ability.

 

[scotts]

Kev, I think it would be very hard to overflow your sump with everything running. I can't really think of a way to overflwo your sump. Now causing your tank to overflow is another story and pretty easy, also easy to make sure your tank does NOT overflow also.
As far as a power outage situation there are 2 ways for water to get from your tank to your sump. The first as you stated is the nothces in your HOB overflow. The second and more important is the line going from your pump into your tank. This will actually siphon water until the water level reaches the bottom of this pipe in your tank. So either you would need this return to be near the top of your tank, or drill a hole in this line just slightly below the water level of your tank. This way if your power goes out the hole will break the siphon.
Of course after you install everything you would need to kick the power off to everything to make sure that it all works right.

 

[kevtheiris]

ya ignore the tank overflow q... bad case of head-up-rear-itis, was thinking about it and figured it out myself...
I just have to find a check valve for the return (sump->tank) lone to keep it from overflowing........
do you just buy one @ Home Depot or similar in the plumbing dept?

 

[ameno]

I would not use a check valve, just drill a small hole in the return piping right at the water level, this will break the siphon.

 

[snakeblitz33]

Originally Posted by ameno
I would not use a check valve, just drill a small hole in the return piping right at the water level, this will break the siphon.

agreed. Check valves fail over time.

 

[scotts]

Kev, have to agree with the no check valve. There are 2 main types of check valves. One is spring loaded, so you have to push against the stopper to open it up. This of course will reduce your flow. The other type is a flapper, the flapper can and will get covered in the slime that gets built up in your pipes (ever clean out your powerheads?) and either the flapper will get stuck in the open position or will not close fully. Of course you can clean the vavle all the time but the one time you don't will be the one time that you need it.

I just make sure to leave enough room im my sump for any backflow that I may get to a power outage. But then again I have an old 55 gallon tank used as a sump on my 125, so I have room.

 

[nigerbang]

Originally Posted by Scotts
Kev, have to agree with the no check valve. There are 2 main types of check valves. One is spring loaded, so you have to push against the stopper to open it up. This of course will reduce your flow. The other type is a flapper, the flapper can and will get covered in the slime that gets built up in your pipes (ever clean out your powerheads?) and either the flapper will get stuck in the open position or will not close fully. Of course you can clean the vavle all the time but the one time you don't will be the one time that you need it.

I just make sure to leave enough room im my sump for any backflow that I may get to a power outage. But then again I have an old 55 gallon tank used as a sump on my 125, so I have room.
I had a giant check valve...Spring loaded...Well add about 2 grains of sand in that and see what happens when the valve gets lodged up...I had 2 bottom flow returns in my 180...I got the water to stop after it dropped about..I dunno.....60 gallons....No more checks or Bottom returns for me..

 

[kevtheiris]

Originally Posted by Scotts
I have an old 55 gallon tank used as a sump on my 125, so I have room.
Im using an old 55g on my new 55g
I know i have room just trying to help out

 

[scsinet]

Originally Posted by NigerBang
I had a giant check valve...Spring loaded...Well add about 2 grains of sand in that and see what happens when the valve gets lodged up...I had 2 bottom flow returns in my 180...I got the water to stop after it dropped about..I dunno.....60 gallons....No more checks or Bottom returns for me..
Yep I flooded my office at work badly by trusting a check valve.
The resistance they place on the line causes the amount of head pressure on the pump to rise, reducing flow, and their mechanical nature makes them prone to failure.
Siphon breaks simply do not fail as long as they are kept clean. Check valves WILL fail sooner or later. Unfortunately it'll be when you are asleep or not at home when they do....

 

[haktran]

Not trying to hijack this thread, but may I ask one tiny question. How do you prevent the DT overflow if something happen to your overflow box and the siphon broke?

 

[ameno]

you would just pump all the water out of your sump, have to be sure there is enough room in the DT to take in the sumps water

 

[bkvreef]

Originally Posted by SCSInet
Yep I flooded my office at work badly by trusting a check valve.
The resistance they place on the line causes the amount of head pressure on the pump to rise, reducing flow, and their mechanical nature makes them prone to failure.
Siphon breaks simply do not fail as long as they are kept clean. Check valves WILL fail sooner or later. Unfortunately it'll be when you are asleep or not at home when they do....
What size of hole should I drill into the return? I also was told it should be above the water. I thought it sounded odd because it would be spraying water all over (wouldn't it?).

 

[scotts]

Haktran, I was going to say welcome to the boards, but then I saw your join date and I guess I better say, what took you so long for your first post?

It is pretty hard to prevent anything happening to your tank if there is a problem with your HOB overflow. Although there is not much that can happen to your HOB overflow. I do know that one person had a snail crawl into their U-tube once. So personally I would equate the dangers of something happening to the overflow like worrying about the seams splitting on your tank. Not much you can do to prevent it and just hope it does not happen.
bkv, I am not sure what size hole to drill, I have my return line at the top of my tank. I know that the smaller the hole the harder it would be to keep clean. You might want to search the equipment forum for the answer to this.
See if this will help you. Don't forget this in only PVC so if you don't like it, rip it out and put a new line in. https://forums.saltwaterfish.com/t/280371/where-to-put-siphon-break-holes

 

[ameno]

I think the hole I drilled was 1/8", I would say no smaller then that. I drilled right at the water line that way I can just look and see the water skimming across the top and I know it's not plugged, I have also on another tank drilled an extra hole about an inch fauther down just in case something happens and the top one plugs I had a back-up hole.

 

[mrinelfrlz]

if you are really serious about doing this i will get "TURNING TIM" to check out this thread

believe me he helped me with mine
75 gal DT, over the top overflow with 55gal,, sump/fug "from the basement"
works excelent!!!
just let me know

or he may just find it before you respond anyways!

 

[haktran]

Scotts, thank you for a warm welcome. Well I guess I did not have to ask questions because you guys are so good in this board. I found all of my answers by reading. Again thanks to all genious out there.