How big of a return pump is needed?

[Northlax16]

I am setting up a marineland 125 gallon aquarium. It has two overflows/returns in the back 2 corners. First, how big of a return pump would you recommend? Second, would you use one pump and plumb it so it goes to both returns or use two pumps and attach one to each return? I currently have an 800 GPH pump I was planning to use for this, is that enough?

 

[Rmckoy]

I would personally get a bigger pump as long as the over flow can handle the flow …

example I have 1 dc -15000 jeabo for my 230
Split into a t for 2 returns into the display
But I only have 1 bulkhead overflow

 

[bushdoc]

Rule of thumb now is for pump to circulate whole volume 4-6x/h. 800 gal pump is rated at 0 head , so you either have to look at pump flow curves or just as Rmckoy said go for more. 800 gal pump is probably marginal as your head will be at least 6-8 ft so flow will be much lower. Each 90deg elbow adds to pressure loss too.
Here is the calc if you want: https://www.plasticpipecalculator.com/PressureDropHeadLoss.aspx
There is many DC, controllable pumps on the market, some for reasonable prices, so if you get one you can control the flow.
It is always better to have 2 pumps, but somewhat it seem as many reefers, including myself are utilizing single one for simplicity.

 

[mike550]

I have a 125G with two returns and am using a Vectra M2

 

[mfinn]

I am setting up a marineland 125 gallon aquarium. It has two overflows/returns in the back 2 corners. First, how big of a return pump would you recommend? Second, would you use one pump and plumb it so it goes to both returns or use two pumps and attach one to each return? I currently have an 800 GPH pump I was planning to use for this, is that enough?

A 800 gph pump at zero head would be a tad small for a 125 gallon tank IMO. I think you should go for 4x to 5x the tank volume for flow at the tank. Or around 600+ gph at the tank.
There are a number of DC pumps available now that work great and are very quiet that don't need valves like a AC pump probably would.

 

[Rmckoy]

Rule of thumb now is for pump to circulate whole volume 4-6x/h. 800 gal pump is rated at 0 head , so you either have to look at pump flow curves or just as Rmckoy said go for more. 800 gal pump is probably marginal as your head will be at least 6-8 ft so flow will be much lower. Each 90deg elbow adds to pressure loss too.
Here is the calc if you want: https://www.plasticpipecalculator.com/PressureDropHeadLoss.aspx
There is many DC, controllable pumps on the market, some for reasonable prices, so if you get one you can control the flow.
It is always better to have 2 pumps, but somewhat it seem as many reefers, including myself are utilizing single one for simplicity.

I’ve always questioned if I added a second pump .
one will maintain some sort of balance as it goes over the overflow into the sump .
I believe adding another pump would only complicate everything

 

[Gtinnel]

For the same tank I use a Jebao DCP-10000, so around 2,600 gph, split to both returns. I don’t run it on max though so I can’t say exactly what my flow rate is but it’s likely more than a 800gph pump can push by the time you add in the head pressure.
Id go for a bigger pump and would strongly recommend the Jebao return pumps.

 

[mfinn]

Second, would you use one pump and plumb it so it goes to both returns or use two pumps and attach one to each return?

I've never liked trying to add a second pump to any of my systems. I've seen all the arguments for using dual return pumps.
I've always used a dependable brand.

 

[Rmckoy]

For the same tank I use a Jebao DCP-10000, so around 2,600 gph, split to both returns. I don’t run it on max though so I can’t say exactly what my flow rate is but it’s likely more than a 800gph pump can push by the time you add in the head pressure.
Id go for a bigger pump and would strongly recommend the Jebao return pumps.

When I chose the 15000L they didn’t have the 20000 in stock
I run this pump at 90%

 

[Gtinnel]

When I chose the 15000L they didn’t have the 20000 in stock
I run this pump at 90%

You are also running it on a decently bigger tank than mine or the OP though.
I actually tried running my pump higher but my return is just two durso drain pipes and if I increase the flow they start to get loud.

 

[Rmckoy]

You are also running it on a decently bigger tank than mine or the OP though.
I actually tried running my pump higher but my return is just two durso drain pipes and if I increase the flow they start to get loud.

I managed to get used to the loud sound of water
If the power goes out it’s almost an odd silence and something isn’t right .
I sometimes wish I still had a smaller tank around 90-120 gal

 

[Gtinnel]

I managed to get used to the loud sound of water
If the power goes out it’s almost an odd silence and something isn’t right .
I sometimes wish I still had a smaller tank around 90-120 gal

I agree and don’t mind the sound of water flowing either, before getting back into the hobby several years back I would often keep desktop fountains to get the water noise. The problem was with too much flow I was getting a toilet flushing noise when it would have enough flow to create a full siphon and then breaking siphon.
Full disclosure I didn’t put a lot (or any) effort into “tuning” my durso to get it to work quieter.

 

[OfficeReefer]

I am setting up a marineland 125 gallon aquarium. It has two overflows/returns in the back 2 corners. First, how big of a return pump would you recommend? Second, would you use one pump and plumb it so it goes to both returns or use two pumps and attach one to each return? I currently have an 800 GPH pump I was planning to use for this, is that enough?

How many turns in the pipe and how long is the return pipe and size as this impacts the flow?

Also, do you have anything else attached like UV or what not?

 

[Koigula]

This is more of a risk question. Not a popular opinion, but Danner Mag just do not break. Sicce AC loose rotor pumps are good value too.

Imagine the scenario of orders of failures two DC pumps will have! Default to 100%, One comes on , one does not,. Diver fails, motor seizes...

Having two circuits, and one to just barely push flow and one to increase flow might work. Instead I opted for 4 - mp40s on aftermarket deep cycle marine batteries in sump and tank.