return pump issue, big dilemma, need advice

[harryk]

Hello all,

I have completed plumbing my new 215 and aside from 2 small leaks it went pretty smoothly with no major catastrophes. Now to my dilemma. I have a 75G acrylic sump and the return pump i am using is the Blueline 70D 1750GPH rating. When the pump is on and running with the ball valve completely open it drains the return chamber of my sump almost dry and sucks air. I have to close the valve 3/4 of the way in order for it to keep water in the return chamber. I thought of diverting water back into the sump chamber from the pump in order to keep it full, but IMO i think this would be a big waste of a nice pump. The pump is currently pushing 1400GPH and my sump cant keep up with it. I was thinking about getting a smaller pump the Blueline 55D it will push about 1000GPH with the way my tank is plumbed. I'm very frustrated and i would love to keep the 70D but i think it might be too powerful. All opinions and advice greatly appreciated.

Harry

 

[kenbow19]

I would try to increase the size of the chamber some how, it might be best to step down in pumps with that size sump, it may prove to be very hard to tame the micro-bubbles with that much flow.

 

[Tang Salad]

Is it your sump, or your overflow that's causing the slowdown?

 

[harryk]

<a href=showthread.php?s=&postid=12542307#post12542307 target=_blank>Originally posted</a> by Tang Salad
Is it your sump, or your overflow that's causing the slowdown?

I think it's most likely the sump, but i'm not sure. I have 2 1" overflows. that rate at 600GPH each. so at a minimum 1200GPH should be flowing thry my sump. But this might be related. in my left overflow box which is right above the drain baffle for my sump the water level drops about 3-4 inches and then the water fills up to the normal levela again. while the right side overflow has a constant water level. is this because the drain line on the left side is so much shorter and the water is draining too quickly.

Thanks
harry

 

[NeveSSL]

I would bet its your overflow. Using a 1750GPH pump on 1" drains that are "rated" at 1200GPH... well... your math isn't adding up, bro.

Brandon

 

[asm481]

OK one thing at a time here. You either do not have enough water in the system. Or your pump is overpowering your drain capacity. If your figures on gph being returned to your tank I see to much return by 200 gph. If you pour more water into the sump while it is running what happens? My money is on a tank overflow! Not good. Throttle back the pump, they do not mind a bit of back pressure.
As far as the overflow "surging", You need to enlarge the hole in the top of that durso. Drill it a bit at a time, small increments.

 

[NeveSSL]

Good point, ASM. He may not have enough water in there. Didn't think about that one.

But I agree, I think its the overflow. Two 1" drains are just not enough.

Brandon