A safe return

[Blobfish]

Hello my fellow addicts,

I am in the process of building a ~250 gallon Aquarium....72" long x24" wide x30" high. I will be using a ghost overflow with three 2" bulkhead fittings for a bean animal set up. I believe I will need 2 1" returns. I would like to locate the returns as low as is reasonable in the aquarium (say 4" from the bottom) for aesthetic reasons. Each return will have its own pump. What is the smartest/safest way to ensure there will be no back flow when the pumps fail. Is there a recommended check valve? Can redundancy be built in?

thank you for any advice you can provide!!

 

[Jhay3513]

Hello my fellow addicts,

I am in the process of building a ~250 gallon Aquarium....72" long x24" wide x30" high. I will be using a ghost overflow with three 2" bulkhead fittings for a bean animal set up. I believe I will need 2 1" returns. I would like to locate the returns as low as is reasonable in the aquarium (say 4" from the bottom) for aesthetic reasons. Each return will have its own pump. What is the smartest/safest way to ensure there will be no back flow when the pumps fail. Is there a recommended check valve? Can redundancy be built in?

thank you for any advice you can provide!!

I always thought you needed a siphon break to stop back flow. A check valve can fail without warning. Why not drill them close to the water line and use loc line to keep them hidden. Especially if your background will be black.

 

[esoxlucius]

It would have to be some check valve for me to trust it would never ever fail in a tank that size and only 4" from the bottom of the tank. That is a LOT of water on your floor. As mentioned, nearer the surface would be safer wouldn't it and you'd have a good bit of surface agitation going on too.

 

[DN328]

As mentioned, check valve and siphon break are good approaches.

I only have a check valve, but my return loclines are also near the surface. I prefer that for safety reasons AND I like a lot of surface agitation.

I too wanted a clean look being a peninsula setup, I dont think having loclines at one end of the tank looks bad. If you have front facing I think it would look just fine, imo.

 

[Jhay3513]

As mentioned, check valve and siphon break are good approaches.

I only have a check valve, but my return loclines are also near the surface. I prefer that for safety reasons AND I like a lot of surface agitation.

I too wanted a clean look being a peninsula setup, I dont think having loclines at one end of the tank looks bad. If you have front facing I think it would look just fine, imo.

With my black background I can honestly barely see my loc line in my tank. I have one pointed down into the tank and one at the surface. My aquarium barely back siphons 2" of water when my pumps turn off

 

[DN328]

I have one pointed down into the tank and one at the surface. My aquarium barely back siphons 2" of water when my pumps turn off

Yup. But even with siphon break holes, OP should make sure it's at a safe level. 2" water drop from back siphon in a tank can make a big difference on 75 gallons vs a 260 gallons.

 

[Drstrangelove]

Check valves can fail and siphon breaks can become clogged. Does this happen a lot? I'm sure it doesn't, but one disaster can last a lifetime.

The only method that is full proof is one in which the tank water levels falls below the inlet for the outflow. The overflow or the take up inlet have to be very high or the surplus volume in the sump has to be very large.

An alternative of course is to overflow your sump into a drain. That protects the floor, but it doesn't protect the livestock if the tank drains to 4 inches. If I could overflow the sump into a drain, I might be comfortable with the tank dropping to 10". But 4" doesn't live much safety margin for anything except the smallest fish.

And of course, if the condition persists for 24 hours, there's the toxic buildup in a very small water volume.

Finally, there's also the issue of what happens if the power comes back on after the tank has drained.

If there are other options, I'd be the first to be glad to be wrong on this.

 

[Jhay3513]

Yup. But even with siphon break holes, OP should make sure it's at a safe level. 2" water drop from back siphon in a tank can make a big difference on 75 gallons vs a 260 gallons.

2" in my sump not the display. My locline is closer to the surface than the actual siphon break

 

[Fish Tank Travis]

Best way would be to make a 500 gal sump and only run it half full. Lol

Honestly, I don't see any way to "safely" ensure that a return located 4" from the bottom of the tank will not backflow and overflow the sump. With all of the algae and scale that builds up inside the lines, the seal on a check valve will not seal reliably. You obviously can't drill a siphon break if it's that low in the tank.

Your best bet is to go ahead and setup the returns toward the top of the tank with proper siphon breaks.

If you just want circulation on the bottom, you can always drill some bulkheads down at the bottom and run closed loop circulation.

Why do you want the returns so low?

 

[Oughtsix]

From the exterior side of your return bulkhead that is 4" above the bottom of your tank put a 90 elbow and run a vertical pipe to above the waterline of the tank. On top of this pipe add two more 90 elbows forming a U. After the U add your flap check valve. From the flap check valve run a hose down to the exhaust port on your sump pump.

At the top of the U drill a 3/16" hole and cement in an air line one valve positioned so air can enter the tube but won't allow water exit through the valve. If the power is cut off the flap valve should close preventing a back wash. If the flap valve fails to completely seal the air line check valve should allow air into the U, breaking the siphon and adding a second layer of protection against backwash. Foolproof?... No... Extra insurance... Yes!

Run a few inches of air line from the airline check valve on top of the U to above the water level in the tank. If the air line check valves fails and lets water through the water will end up in the tank.