Return pump size: based on drain only?

[SteveG_inDC]

Should the size of the return pump be based on the capacity of the overflow drain capacity?

That's what I always assumed but there are a lot of old threads on forums saying to push high volume through the sump for efficiency (like 10X water volume). I don't see how you can even do that if the drains can't handle it.

I am planning a 240 display with 100 gallon sump, have a chance to buy a used mag drive. the guy has a mag 12 and a mag 18 and I have a mag 7 and 9 lying around. So many choices.

I have not actually bought the tank yet or specified the size of the holes for the drain plumbing.

 

[Aardvark1134]

You would be surprised how much a 1.5 or 2 inch full syphin can pull

 

[chowberg]

I have (2) Glass Holes overflow plumbed with 1.5 inch PVC pipes (plumbed Herbie style, 1 full siphon with a gate and 1 emergency/overflow). I had a Fluval Sp4 on the return pushing 1000+ GPH and it was zero problems.

The issue I ran into though was pushing that much water still caused quite a bit of noise through the pipes. I think the issue is my Glass Hole overflow boxes.

 

[Aardvark1134]

To make an over flow quiet you usually want 2 things. First a full bean. Second you need to fine tune it just 10 percent more or less water going through the non full syphon can make a world of difference

 

[chowberg]

To make an over flow quiet you usually want 2 things. First a full bean. Second you need to fine tune it just 10 percent more or less water going through the non full syphon can make a world of difference

Unfortunately, full bean isn't an option for the way my tank is plumbed right now (double unfortunate because my sump is pre plumbed for 3 drains too). I tried adjusting with a gate valve, but when I couldn't fine tune it to where it was a slight trickle into the overflow/emergency drain. The full siphon would pull too much water and the other drain wouldn't be utilized, or the overflow drain would make noise. I am using a gate valve (instead of a ball valve) too! I ended up switching to a DC return pump and was able to adjust the amount of flow.

 

[Snoopy 67]

You should do a Bean style overflow using 3 holes, it's the safest one out there.
I run a Herbie on a 250 with 1" piping but not too much flow. I could go higher with a different pump.
If you want a high flow pump I would do 1.5" piping.

 

[Snoopy 67]

Remember - with mag pumps to achieve the rated flow you will need large piping on the return.
Varios pumps are good DC pumps & might suit you better. They run quiet, are adjustable & do not run hot.

 

[KIRBLIT]

I'm a big advocate of high turnover. I have a 300 display and I push about 50gpm through it on a 1.5" bean setup. It's all preferance really, but just make sure your drains DO handle whatever your pump can throw at them.