40mm overflow sump question

[Ramesh]

I am going to fill my 500g over Easter and have two 40mm overflows that drain to my sump (see pics).
The sump is a 4x2x2 wet/dry and I want to run a Rio 20HF for the return.
The Rio 20HF can pump 1290gph at 1ft and 990gph at 4ft and 870 at 6ft.
My stand is 80cm high and the tank returns 60cm, so the pump output should be about 950gph.

I need to know what kind of rate can I expect from the overflows draining to the sump??
Will I need another sump pump??

The first pic is of the LHS overflow drain and the second is of the RHS overflow drain with has a 25% water change valve fitted also.

I have three drains and three returns. One pair is for the canister and the others the sump.
I will split the return flow from the Rio20HF or use it to for the second sump pump if I need one.
I will have ball valves fitted the the overflow drains also (not yet fitted the the right overflow)

 

[Ramesh]

BUMP

 

[Donny417]

Well, your turning your water 2x per hour with that setup. Your overflows are going to be capable of 6-8 times that amount (40mm is almost 2" Dia.)

The problem is, you need to turn your water a minimum of 5x per hour, but ideally 8 times per hour in a tank that big.

So, ideally you'd move 4000 gallons per hour.

 

[Donny417]

Also, the way you have your overflows you might have a hard time getting them to keep up...

 

[CHOMPERS]

(40mm is almost 2" Dia.)

40 mm = 1.574"

 

[CHOMPERS]

Each overflow in that configuration will flow 844 gph, so two will flow 1688 gph.

 

[Burko]

"so two will flow 1688 gph"

Slow down egghead...

 

[Ramesh]

Then I'll need another sump pump to return the water (2x Rio 20HF) or I could reduce the drainage flow using the ball valves.

 

[CHOMPERS]

No, you don't want to reduce the drainage. It will only drain what the pump puts into the tank. The overflows need to be able to flow more than the pump. Otherwise the pump would drain the sump and the tank would overflow onto the floor.

 

[Ramesh]

O.K. so you don't think I need another Rio 20HF.
I thought I may need another pump because the overflows were draining more than double the pump output.