Overflow Ruh Roh, Help!

[Curren007K]

I need some help.

The previous owner of my 180G display drilled two holes through one of the corner baffles.
I was never able to 100% leak proof these, as a result I ran my return line through both with a bulkhead in each.
When I tested the tank out and cut the power the water in the main chamber would continue to leak through the two bulkheads in the baffle until it leveled out with the water level in the overflow.
This was fine when it was happening, 6" of water from the display tank would continue to leak into the overflow and down into the sump, totaling about 45 gallons which my sump could handle before leveling out.

I lost power briefly today while I was at work. My wife called me to tell me a lot more than 6" of water was lost from the display tank. Almost half the tank, 90G of water from the display made its way into the sump, luckily the sump did not overflow. We've since regained power but is this happening now and not before? Is it compartmentalized so the force of the water is pushing its way through from the display into the overflow no matter the level? Maybe the durso stand pipe is loose so it wasn't holding the water level in the overflow, allowing more to escape? I'm at work now just brain storming why this is happening. Here's some very crude drawings in paint. Any help would be appreciated.

Normal operation:

Normal loss of power: Loss of 6" or 45G of water from Display into sump.

Current loss of power: Loss of 12" or 90G and continuing from Display into sump.

 

[Curren007K]

Drawing 3 is irrelevant.
I think the stand pipe had to have been loose, I just checked with my wife and the water level in the overflow was the same as the display when it kept falling.
It must've been escaping through the bottom of the durso stand pipe.
Even so its proven to be unreliable to retain the water during power outages.

Any ideas for a permanent fix?

 

[Bandit13]

Don't know for sure but it might be back siphoning from the lower outlet of your return piping. That's my first guess

 

[Curren007K]

Don't know for sure but it might be back siphoning from the lower outlet of your return piping. That's my first guess

I have two ball check valves in the return line, you can visibly check if they failed as well.
I wasn't the return line in this case.

 

[dz6t]

Seal those two holes off. Water will drain to the level of the bottom hole when return pump is not pumping water.

 

[B.rian]

i agree with dong. seal those 2 holes or maybe use them as some kind of closed loop system that can't drain into the overflow.

 

[wpeterson]

+1 for return lines siphoning down to the sump. If this was not initially happening and was prevented by a check valve - it's likely your check valve failed or stuck open.

Many folks don't recommend using check valves on your return lines due to just this kind of failure.

 

[Curren007K]

Any ideas on how to seal those holes? Bulkheads don't work, water leaks right through the gaskets since its a curved corner baffle.

 

[dz6t]

Get a piece of thin plastic from HomeDepot, use superglue to glue over the holes.

 

[IPWitan]

how about this - close the bottom return opening and potentially raise the top one. You may be able to simply cap it. If that top hole and the dorso are the same height, then that should be your water level. If the area around the holes is not sealed, it will equalize but not drain beyond the top return/dorso height. Thus, even if the pressure on the check values creates a slow leak, it still won't go lower than the top of opening.

Frankly, I cannot imagine any way into my sump that would not have a high point such that it won't siphon beyond the top inch or two of the tank. That honestly sounds like a major disaster in the making. It seems at best check values merely slow a siphon/drain, not eliminate it.

 

[JohnK]

Cap or permantly seal those holes. No way around it that I would trust.