Bigger overflow box = +1 pump in sump?

[reeferoo]

Currently I have a 750 GPH overflow on my 60 gal tank.
I have a 20 gal sump with a Mag 7 return pump (and a sock and a Mini G Skimmer)

I also have a chiller (currently not hooked up- moved to a smaller place- using AC for now)

Last summer I pushed my water with my Mag 7 through the chiller then up to the tank. My turnover greatly decreased (logically)
My corals suffered and this setup will not work again without a more powerful pump. I have heard people say they need to throttle back the Mag 9.5s in tanks bigger than mine.

This got me thinking:
I have a spare Mag 3 sitting around (backup pump)

I figure I have maybe 5-600 GPH from the Mag 7 with the 4' of head and I figure I would have maybe 200 GPH with the Mag 3 pushing through the chiller then the 4' head.
(note: I have no idea now close these GPH approx are- I need to get a flow meter or somehow hold the output up 4' and see how long it takes to fill up my bucket or something)

So say that is about 8-900 GPH of input to the tank.
So if I upgrade to an Ehsopps 900 GPH overflow, could I put both pumps in my sump (I have room in there)

What are the pros/cons of this idea?

thanks so much everyone!

 

[evsalty]

The Mag 7 pumps 500 @3' and 375 @6' so you are probably pumping 450 if you truely have 4' of head. Have you considered running your mag 3 thru the chiller and back to the sump? Also overflow boxes do not flow as much as they are claimed due to not having the full weight of the tank volumn on them like a drilled tank overflow does. A 1" bulkhead used at the bottom of the tank can flow 600gph but it is more likely to get a max of 400gph when a 1" bulkhead is used in an overflow box. I had to turn both of my overflow boxes to dual 1" drains to get over 1000gph of flow down to my sump.

 

[reeferoo]

This is an excellent suggestion.

At first I though 450 is not enough turnover for my tank, but with the sand and rock displacement I probably only have 45ish gallons total which is 10x turnover which is pretty ideal.

Is there a sneaky way to measure turnover without a flow meter?

What would be a disadvantage to the initial idea of adding a pump to the sump (considering the possibility that even with it I still wouldn't get too close to the 750 GPH overflow- I'd approx 600 GPH max)

 

[evsalty]

Well a mag 3 at 4' head pluss the additional head of the chiller will probably be under 100gph. I would say try a mag 9.5 or 12 and run it thru the chiller and up to your tank or try what I said befor since you would not have to spend anything right now and you would get some cooling benefit until you get a bigger pump. As for having to throttle back a 9.5, the chiller will add head pressure and take care of that. With the 12 you might have to throttle it back or add 1 or 2 90 degree elbows which will add more head.

 

[reeferoo]

fabulous. I will keep an eye out for a good deal on a mag 9.5 then I can still have a backup pump.

In the meantime if my AC doesn't cut it, I can hookup the chiller into and out of the sump as suggested

thanks so much!

 

[evsalty]

welcome