water level dropping too much in tank with no power

[TitansFan]

Just looking for some help and ideas here...
I am finishing up my 150 gallon tank build. Other night I did a no power test to see if my sump could handle the extra water. Well my display seems to keep draining quite abit. Much more than my 65 gallon. The water level goes alot lower and seems to keep going down slowly over time.

It is a perfecto 150 gallon with the perfecto issued durso pipes. Is there something I am missing or need to look at? I think I have the durso pretty well seated.

Thanks

[cdness]

if it is draining slowly you either have a leak somewhere or a check valve is failing. I have my check valve on the return line leak not too long ago. I shut everything down for return pump cleaning and my sump was REALLY full. it never filled up that high so I figured it's got to be the return line.

[jtarmitage]

How low in the water are the return nozzles? Is it draining below those?

[LockeOak]

When this happens to me I raise the surface overflow a quarter inch or so, not sure if that's possible in your setup. Maybe some kind of extension on the durso would work?

[TitansFan]

cdness: i dont use any check valves as I dont trust them.

jtarmitage: I had not thought of that. Could it be they are causing a syphon? I will for sure check that when I get home.

[jtarmitage]

<a href=showthread.php?s=&postid=13612176#post13612176 target=_blank>Originally posted</a> by TitansFan
cdness: i dont use any check valves as I dont trust them.

jtarmitage: I had not thought of that. Could it be they are causing a syphon? I will for sure check that when I get home.

That would be my first guess. If they are, you can do a couple of things. Either raise them so the tip of the nozzle is just barely below the normal water level, or drill holes in the return, either just above, or just below the normal water level, or both. That way it'll break the siphon.
As for the durso's being seated or not, once the water level in the tank drops below the teeth of the overflow, the only water that can still drain into your sump, assuming the bottom of the durso's are not sealed, is what's in your overflow box. Though, I guess that assumes that your overflow box is still intact and sealed.

[TitansFan]

Is it normal for the whole overflow box to drain? My 65 gallon is a perfecto tank as well with same durso setup and it does not drain this much.

Unfortunatly, I do remember checking to see where the water is draining to the sump from and it is the drain.. not the return. I assume that would cancel the easy fix of the syphon in the return.

[jtarmitage]

<a href=showthread.php?s=&postid=13612263#post13612263 target=_blank>Originally posted</a> by TitansFan
Is it normal for the whole overflow box to drain? My 65 gallon is a perfecto tank as well with same durso setup and it does not drain this much.

Unfortunatly, I do remember checking to see where the water is draining to the sump from and it is the drain.. not the return. I assume that would cancel the easy fix of the syphon in the return.

If it's from the drain, then it's draining the tank down to the bottom of the overflow teeth, then draining the overflow box. 3 options that I see:
1: Get a bigger sump (not always possible or practical)
2: Lower the normal water level in your sump to accomodate more from the tank during a power outage
3: Seal the durso/bulkhead connection better. If your durso isn't threaded, or even if it is I guess, I have used teflon tape wrapped around the bottom of the standpipe. Wrap a couple layers tightly, then push it into the bulkhead fitting. It should fit very snug, making sure that the teflon doesn't just get pushed up and out of the way.
You could also use silicone. Put a bead around the bottom of the standpipe and push it in. It will make removal more challenging, but it can still be done.

[IslandCrow]

The entire overflow box should not drain. If it is, you have a bad seal between the bottom of the tank and the standpipe. Also, as stated, your return plumbing could be an issue as well. As soon as that plumbing fills with water, you automatically have a siphon. Turn the pump off, and water will flow in the easiest direction (i.e. down into the sump) until air enters the system and breaks the siphon.

How low your tank drains after power loss should never be a surprise. It should drain to the bottom of your overflow teeth or the top of your return pipe opening (or siphon hole), whichever is lower. If that's not the case, something's plumbed incorrectly.

[AZDesertRat]

It should only drain to the bottom of the overflow teeth or the level of the standpipe which ever is lower. If its going lower the standpipe is not sealed.
I would also avoid drilling holes in the returns as this is just a false sense of security and like a check valve will one day fail and cause a flood. The only positive way to prevent backsiphonage is with an air gap once the water has siphoned the inch or so until the returns are exposed to atmosphere. All it takes is a piece of algae or a snail to defeat drilled holes.