water outflow question - in/out pump ratio?

[soulFish]

I know that most acrylic tanks have the hole cut at the top or the bottom for water outflow into the sump system. But what about glass tanks? I've heard you can have a glass company drill them, but you risk total failure doing so.

SO if you were not going to drill your glass tank, is there a ratio for the "water outflow" to the "water inflow" pumps?

 

[rallysman]

You don't need to pump water out of the tank. They (or you can) make overflows that hang over the back of the tank.

As long as the overflow that you go with (be it DIY or pre-made HOB) can flow more than the pump will deliver back into the tank you'll be fine.


Here is a pre-made overflow, and there is a sticky on the DIY one in the DIY section.

 

[soulFish]

So you will always draw out more water than you pump back in then. Seems logical, that way it will ensure your refugium doesnt go dry. But then you could risk overflowing your sump. So is there a general rule to like 1 -to- 2 or something along those lines? Something to gauge what sized powerheads to buy?

 

[boisblancboy]

So you will always draw out more water than you pump back in then.

No, you only drain out what you pump in.

Seems logical, that way it will ensure your refugium doesnt go dry. But then you could risk overflowing your sump. So is there a general rule to like 1 -to- 2 or something along those lines? Something to gauge what sized powerheads to buy?

The only way you risk overflowing your sump is if your pump fails or power goes out. Some water is going to drain from the tank back to the sump through the overflow, but generally not very much. Also you have to make sure that your return lines dont syphon back or you will have a problem. Either have them above the water line, holes drilled in them to act as a syphon break, or a in-line check valve.

 

[Dr Joe]

rallysman, why flow more than you pump back, once sump is filled you've reached an equilbrium that you now want to maintain...right?

Put anti-siphon holes on the return also, if return is below water level it can drain back thru the pump during a power outage or pump failure.

Dr Joe

.

 

[rallysman]

rallysman, why flow more than you pump back, once sump is filled you've reached an equilbrium that you now want to maintain...right?

.

It needs to be able to flow more than the pump can return. I didnt mean for that to sound like it needs to flow more......but it does need to be capable of it.

If the pump and overflow rate were equal a piece of food stuck in the overflow could make the difference in draining your sump and overflowing the tank. It will only flow as much as the pump will return so why would you want their rated flow to be equal?

 

[Dr Joe]

That's what I thought you meant. Thanks for clarifying it.

Dr Joe

.

 

[soulFish]

Anyone have a good source for premade HOB overflows?

 

[boisblancboy]

http://www.theaquariumonline.com/detail.aspx?ID=567

These are the ones I like. If you order from them you get the largest one which is rated for 1200 gph if I am not mistaken and I feel that is a fair price they are asking.