overflow, siphon, sump how does that work

[clownchic]

I have never used anything but a HOT skimmer so I'm not quite sure how to set-up a sump/refugium system. My tank is not drilled so I assume I need to have an overflow hanging off the tank like the CPR overflow. This would then lead to a sump/refugium below in my stand. My question is - what happens when you lose power? Doesn't water continue to siphon out of the upper main tank into the sump until it overflows? I am just fearful because we lose power a couple of times per year. This is probably a stupid question but I just have to ask.

:confused:

[shakestheclown]

It depends on how low the overflow box is situated relative to the water level in your tank. If your sump is large enough, when the pump looses power, the volume of water above the overflow box will drain to your sump, plus the volume of water to the bottome of your highest return line outet. Most set-up, the return line outlet is below the overflow box level. If you drill a small hole just below the normal water line in the return level, you should suck a minimal amount of water into your sump before the air into the small hole breaks the siphon

[KEITHMC]

an overflow will stop when the power is off what you have to watch for is your return lines backflowing in to the sump that is why you drill holes in the return line to break the siphon!!

[clownchic]

Just to make it clear for me - the return line is the "hose or tube" going from the overflow back to the sump. Exactly where do you drill the hole in the tube? In the overflow? I'm usually not this dense- really!

[KEITHMC]

the return is from the sump to the tank an overflow will stop flowing when you stop putting water in to the tank the returns to the tank are normally submerged and when the pump is turned off water will siphon back to the sump till the returns are no longer submerged thus you drill the holes in the returns just below your normal water level

[Dubbin1]

<a href=showthread.php?s=&postid=7135315#post7135315 target=_blank>Originally posted</a> by clownchic
Just to make it clear for me - the return line is the "hose or tube" going from the overflow back to the sump. Exactly where do you drill the hole in the tube? In the overflow? I'm usually not this dense- really!

The return line is the line that comes from your sump back to your tank. You will want to drill a hole or two in that line at the water surface. Your overflow will stop flowing once you loose power to the return pump since the water will drop below the point to where it enters the overflow box.

[clownchic]

OK. So the holes are drilled maybe a 1/2-1" below the normal water line in the main tank in the line coming FROM the sump to the overflow to the tank. Yes?

[Dubbin1]

The return line does not go to the overflow. It goes right back into the tank. I have my holes drilled right at the surface so it stops the siphon asap.

[clownchic]

The overflow then only has the water coming from the main tank to the sump. That is where I was confused. Thanks so much everyone. I may have to give it a try. I'm afraid my Remora Pro may not be enough for my new 90 gallon set-up.

:rollface:

[Dubbin1]

<a href=showthread.php?s=&postid=7135498#post7135498 target=_blank>Originally posted</a> by clownchic
The overflow then only has the water coming from the main tank to the sump. That is where I was confused. Thanks so much everyone. I may have to give it a try. I'm afraid my Remora Pro may not be enough for my new 90 gallon set-up.

:rollface:

Yup I think you got it now :) I also think you are right that your skimmer is not going to cut the mustard with the new 90g. IMO I would get an ASM G2 or G3 for your skimming needs.

[clownchic]

THANKS!!! :D