How Do You Flood Proof Your Overflow and Sump?

[lzolnier]

Hey guys;

I just got my first sump and refugium and was wondering how you can install the system to minimize any chances of either the tank or the sump overflowing. My sump did not come with any install instructions and so I'm a victim of a flood waiting to happen. I'm especially concerned about an electricity outage, while no one is home, to the extent that I turn off my sump when there is no one there. Poor me, I just don't want my hardwood floors to be ruined. And So i have 3 main questions.

Do all overflow boxes stop syphoning the water into the sump, if the return pump goes out?

Will a flood inevitably occur when the syphon action breaks off and the return pump is still working? How often can this occur?


What can I do to prevent the water, from the main tank, going back into the return pump and into the sump, when the return pump stops working?

Any guidence on making my sump leak proof (including recommaded water depths in the sump) would be appreciated. I have an overflow with flexible tubing and a Remora skimmer in the sump, with Cheato in the adjacent fuge. Thanks!

[der_wille_zur_macht]

Originally posted by lzolnier

Do all overflow boxes stop syphoning the water into the sump, if the return pump goes out?

Yes, by design principle - when there is no longer water entering the display tank, the water level will drop below the box's weir (the edge that the water flows over) and it will stop draining into the sump.

Will a flood inevitably occur when the syphon action breaks off and the return pump is still working? How often can this occur?

Depends on the overflow design. I am guessing you are using a hang-on overflow box? Then yes, if the siphon breaks and the return pump is on, you will basically pump the contents of your sump into the display tank, which will then overflow onto your floor. Depending on the design of the overflow box, this might happen often, or almost never - but there IS always the possibility. The key is to prevent the siphon from breaking. Most good boxes have features designed to prevent this, but it can still happen.

The siphon can break when one of two things happen. Firstly, if the power goes out and water drains out of the siphon tube, it'll break the siphon. Most overflow boxes have little baffles designed into them such that when the power goes out, both ends of the siphon remain underwater, which reduces the chances of it breaking.

The second way a siphon can break is if air bubbles accumulate in it, to the point that water stops flowing and the siphon breaks. One thing you can do to prevent this is to keep the water flowing fast - run the overflow box near it's rated capacity. If you have a box rated at 500 gph and you are only putting 70 gph though it, bubbles will accumulate much more quickly than if you were putting 450 gph through it.

Another thing you can do is provide some active means for maintaining or restarting the siphon. Aqualifter pumps are often used for this, or the venturi fitting on a powerhead. Just position a piece of airline in the siphon such that it ends up at the highest point of the siphon, and attach the other end to the aqualifter pump's intake. This way, the pump will always be sucking away, preventing air bubbles from accumulating.

What can I do to prevent the water, from the main tank, going back into the return pump and into the sump, when the return pump stops working?

Assuming your return line runs up over the back if the display tank, you should implement a siphon break. To do this, drill two or three small holes (1/8" or so) in the return line, JUST below the point where it enters the water. This way, when the pump goes off and water starts draining into the sump, the holes will suck in air, which will break the siphon in the return pump line and stop water from flowing into the sump.

Any guidence on making my sump leak proof (including recommaded water depths in the sump) would be appreciated. I have an overflow with flexible tubing and a Remora skimmer in the sump, with Cheato in the adjacent fuge. Thanks!

The water depth you run in your sump needs to be low enough that when the return pump shuts off, the sump does not overflow. If you implement a siphon break, you should only get a few gallons of water draining into the sump before things stop flowing. The only way to be sure about this is to TEST IT! Cut power to the tank, then stand back and watch. If you planned correctly, things will settle out on their own without your intervention.

[lzolnier]

Perfect, just the advice I wanted. In terms of design and flood safety features, is there an overflow box that is the most highly regarded? Mine came with the sump and its a no name type.

[der_wille_zur_macht]

Generally, u-tube boxes are better than "continuous siphon" boxes. Otherwise, as long as it has certainy features, there's no difference between brands.

The main feature you want is that both ends of the siphon remain under water when power goes out - and as far as I know, the vast majority of models on the market now have that feature.

[singold]

Keep water level on display tank, with respect to overfow box lip level, less water volume that can overflow sump in terms of volume & you will be fine.

[alleykat81]

Originally posted by lzolnier
Perfect, just the advice I wanted. In terms of design and flood safety features, is there an overflow box that is the most highly regarded? Mine came with the sump and its a no name type.

Check out Lifereef overflow boxes.

[Whys]

Use a check-valve. No worries.




Kidding.