Overflow box and heac calcs

[john0087]

I am finalizing the plans for my sump and I have a couple of questions about overflow boxes and my head calcs.

I am planning on using a CPR CS50 overflow box. This is rated at 300gph. Is this the max flow of does it mean that is siphons at a constant 300gph?

I plan on using 2 mag 5’s for my return pumps. I figure that my head is about 7’ 48” for the tank and stand + 36” for 3 90deg bends in the return U tube that I plan to use. The mag is rated at 125gph at this head height, giving me a total flow of 250gph.

Is this all correct?

Thanks

John

[NaClFinatic]

I think the over flow rating is usually a maximum. I would be a little worried that two Mag 5s would be too much. But you could certainly give it a try. Just be ready to pull the plug quick if the overflow isnt keeping up. Also make sure your overflow stays clean and well flowing if you are going ot push the limit of it.

I have a mag 7 going on my 90g through 2 90deg and Id say tis doing at least 400gph.

[NaClFinatic]

Oops sorry I have a quietone 3000 which is almost identical power to the mag7 which I also have as a backup and it performed the same

[john0087]

Originally Posted by NaClFinatic

I think the over flow rating is usually a maximum. I would be a little worried that two Mag 5s would be too much. But you could certainly give it a try. Just be ready to pull the plug quick if the overflow isnt keeping up. Also make sure your overflow stays clean and well flowing if you are going ot push the limit of it.

I have a mag 7 going on my 90g through 2 90deg and Id say tis doing at least 400gph.

Yeah,

I was thinking that was well and I think tghat i will most likely go with 3 mag 3's instead

[NaClFinatic]

3 return pumps? That sounds too complicated. Unless you are using some ofor a closed loop, I would reccommend using 2 max. I only use one. Having two running will keep your system circulating incase one fails, but even that is extra plumbing to do and extra pump to clean. I gues two might be reassuring if you are away frequently for more than a couple days. Other than that I would go with one. You shoudl still have additional in tank circulation anyway. To get just the right flow you could look at other pumps also.

I am guessing your pump is going to be submersed?
Check on enheim pumps. Maybe quietone, but Im not sure if they have somethign in between the 3000 and 1200.

The other option would be to use a blowoff to use a larger pump like a mag 7. Split the return line just after the pump. Run one line right back into the sump and the other up to the tank. but put a valve on each line. Then you can adjust the flow with the valves. The goal woudl be to get the right amount of flow into your tank, but allow enough flow through the blowoff that it does not restrict the pump. though I've seen people do this without the blowoff. I'm not sure what effect that has on different pumps.

[john0087]

Sorry,

It was late when I posted. I meant 2 mag 3's. The mag 3's have a head rating of 120gph at 7'. That would give me 240gph total, with a little wiggle room for error to keep me unde the 300gph max number.

I will still keep my Serio PH to help with the flow in the tank.

[NaClFinatic]

mag 3 are less power and heat in your water too
mag3 ratings are close to mag 5 but might be enought o keep you safe
if not you can always put a vlave on one or both returns to just do some slight throttling of the flow, but I would guess this will be ok
personally I would shoot for only utilizing about 66% of my overflow capacity just to be safe as possible

[CarmieJo]

Here is an article you might want to read too. Advanced Aquarist's Online Magazine - Feature Article: Pump Head Loss Calculator - Easing System Design

[lReef lKeeper]

GREAT link Carmie !! thanks !!

[john0087]

Originally Posted by CarmieJo

Here is an article you might want to read too. Advanced Aquarist's Online Magazine - Feature Article: Pump Head Loss Calculator - Easing System Design

Excelent, thanks!