Flood proof a sump.

TomToro

TomToro

The Old Guy
Oct 21, 2006
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Michigan
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I need my sump to be flood proof. I understand the oveflow level will only go so far and I need that space in my sump in case of a power failure, but...

What if the overflow loses siphon for whatever reason and the pump empties my sump into the main tank, flooding the place. Are there failsafe measures I can take to prevent this? My son suggested a powerhead 'helping' the siphon. I'm not sure how to do that.
Thanks,
Tom
 
depending on how your sump is setup. Usually the return pump is in a return chamber, where it'll only pump whatever is in the return chamber back into the tank. The fuge area won't be touched. The return chamber isn't very large, so your main tank will be able to handle the extra water. Worse case scenario, the return pump will fry once the return chamber is empty and it has no more water to pump. I can't remember where I saw it, but I am almost positive that they sell pumps that will automatically turn off if there is no more water to pump.
 
Check out lifereef.com and their Float Switch page. You can wire the switch to turn off the pump if the water drops below a certain level in your sump, preventing any flooding from occurring if your overflow for some reason lost siphon. It's pricey, but if flood protection is that important to you, it's probably money well spent.
 
Great stuff, guys. Let's see if I've got it:

1. The pump only empties It's own reservoir so if it runs after the overflow loses siphon, it just empties it's own area and the baffles keep it from emptying the entire sump and I leave enough room in the main tank to handle it.

2. If the power dies and the overflow continues, it only empties the main tank where I've adjusted the overlow box and I've hopefully left enough room to accomodate the extra water from the main tank in the sump.

So, how does the sump overflow? Is it just poor calculating or another factor I don't see?

Seriously, this was perfect info to convince my wife there's nothing to worry about. Thanks again!
 
The sump would overflow as the result of an inadequate amount of empty volume left for the water that drains into the sump after the pump is turned off. There's no real way to calculate that amount, it's mostly trial and error. It's best to test this while you have control over it to make sure you maintain enough empty volume in your sump so you don't end up with a flood during a power outage. Once you decide what a "safe level" is for your sump, I'd highly recommend marking it on the sump.
 
That won't work for me because it's glass and already set up. I will however drill my next tank before anything else. I learned.
 
...There's no real way to calculate that amount, it's mostly trial and error...
Click to expand...
Actually it is easy to calculate. There are 7.5 gallons in a cubic foot of water, so the formula in inches works out to be
L/12 x W/12 x D/12 x 7.5 = gallons
This also simplifies to
(L x W x D) x 7.5/1728 = gallons
or
(L x W x D) x .00434 = gallons

Just measure the volume in the sump and then use that to calculate the height of the overflow box.
 
Oh, just a thought...
Here is an easier way. The above formula cancels out a lot of garbage when using it to equate the sump volume and the overflow volume (or surge volume).

The tank dimensions are in caps and the sump dimensions are in lower case.
The tank depth D is measured from the tank's normal fill line to the lowest point of the opening of the overflow. The simplified formula is

D = (lwd)/(LW)

Measure the sump dimensions and then multiply them. Then divide by the product of the length and width of the tank. Most calculators will allow the formula to be keyed as above if it has parentheses keys.

Hope this helps,
Ron
 
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