how to determine overflow rate?

[cbrjenkins]

I just had an custom overflow box built. It only contains the drain, and im having two returns drilled elsewhere on the tank. Im trying to determine what size return pump i need and everything ive read says you need to know what your overflow is capable of. My question is, is there a formula that gives you said output based off of the overflow dimensions?
Thanks in advance!

 

[acroholic]

Most Aqueon and Oceanic overflows use 1" bulkheads for their overflows, and they rate the flow thru them at 600 gallons per hour. That could be a starting point for you. I would look at the bulkhead size you are using more than anything else.
Dave

 

[cbrjenkins]

Thanks for the fast reply! Its an 1 1/2 in. bulkhead fitting. From what i just read it should be good for up to 1300 g.p.h? So, the bulkhead is more important than the actual size of the overflow box? Also, its a twenty gallon sump on a 52 (48x18x18) tank. So, i reckon something like a mad 9.5 or so would be good. And once again, thank you for your help, im new to this sump thing, lol.

 

[kirru]

I built me a custom over flow box for my 40 breeder with 20 long sump. I use a Mag7 and it is a 1.5" bulkhead as well. I get good flow and only have a Tunze 6025 in the display. I think a Mag9.5 would be good for you with some supplemental power heads for deadspots.

 

[ichthyoid]

It would be more accurate (and safer) to just measure it.

A couple of methods:

1) use a stopwatch to time how long it takes for the overflow to empty. You also need to know how much fluid you are using. From these calculate the flow rate.

2) set up a pump that will feed the overflow continuously, and measure the volume of water for a certain time, then calculate the actual flow.

Neither is very hard.

 

[weaglereefer]

A 20g is fine for a 52. I'm using a 20g sump on my 90. I'd go with a mag 7, or even a mag 5 for a tank your size, that is as long as you're not T-ing off to feed anything else like a skimmer or fuge.

 

[cbrjenkins]

ill be teeing off to feed two returns, one on both sides of the tank. Im hoping that by having the overflow in the middle, with a return on each side of the tank using the split lok-line to try to reduce dead spots. That sound like a bad way to go? And would a mag 7 or 5 still suffice having a tee?

 

[weaglereefer]

Yeah, it's still a return. I meant if you were robbing return flow for some other purpose.

 

[grouper therapy]

http://www.reefcentral.com/index.php/drainoverflow-size-calc">http://www.reefcentral.com/index.php/drainoverflow-size-calc</a>
This link should help with the calculations already done.
I am a big fan of slow flow through the sump and using other means for circulation. I don't think that a fast flow through the sump is harmful since the water filtering components are only going to process so much anyway.That being said the fast flow is pointless. However buying a pump large enough to begin with that will handle multiple task is easier and less expensive. The mag 9.5 is a great choice and if it needs to be throttled back some, that is ok too. Throttling back most pumps WILL NOT harm it. They will actually run cooler and use less watts which in theory should extend their service life.

 

[maestro]

grouper therapy;475758 wrote: http://www.reefcentral.com/index.php/drainoverflow-size-calc">http://www.reefcentral.com/index.php/drainoverflow-size-calc</a>
This link should help with the calculations already done.
I am a big fan of slow flow through the sump and using other means for circulation. I don't think that a fast flow through the sump is harmful since the water filtering components are only going to process so much anyway.That being said the fast flow is pointless. However buying a pump large enough to begin with that will handle multiple task is easier and less expensive. The mag 9.5 is a great choice and if it needs to be throttled back some, that is ok too. Throttling back most pumps WILL NOT harm it. They will actually run cooler and use less watts which in theory should extend their service life.[/QUOTE]

thanks for this :up: I always wondered if using a valve to control the output of a pump would harm it.

 

[spacepony]

Forgive the tag-on, but do you put the valve/throttle on the input side, or the return side? Or does it matter?

 

[scuba steve]

Always throttle the discharge, as stated pumps often perform better with a bit of back-pressure. Never restrict the inlet, you starve the pump and cause it to overheat.