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sonoma2nv 01-22-2006 09:07 PM

Overflow problem???
I have a hob overflow its says 600gph but i dought it is.I have a mag 7 and i have to throttle it back about 1/2 way.I have 3/4 pvc return .It splits off so i have 2 returns one at each end.And the overflow has 1" pvc.Should i go with another overflow rated at 1200gph?I have a 55gal with a 33gal sump.If i need to buy a new pump i can. The sump does not seem to be getting enough flow through i had to put 2 ph one in the fuge and one in the return side.Thanks in Advance

tecwzrd 01-23-2006 12:42 PM

The general rule is 1” is supposed to equal about 600 gph but depending on the brand and prefilter/sponge you have it may vary. Does your overflow drain straight\curved down into your sump or do you have a couple of 90 degree bends? Is air trapped in the overflow? How long have you been using it and is the drain clear or need to be cleaned?

With it splitting off to separate sides it should only be putting out about 400 gph so I’d say something is off on your overflow if you have to scale that back to half. (I assume with a ball valve??)

I use the CPR CS102 overflow and it has no trouble keeping up with the mag 9.5. I also like that they have a tech support forum.

fishfreek 01-23-2006 01:16 PM

Speed can also be affected by how you have the overflow plumbed. If you have excessive bends in the overflow drain line it can slow down the effective speed of your overflow. In addition what is the head height of your tank? IE how far up does the mag7 have to pump the water to get to your tank.

I dont fully follow the wording where you say the sump does not have enough flow thru it. What do you mean by this?

sonoma2nv 01-23-2006 05:23 PM

On the overflow i have 2 1"90 leading to the tank.the head height for the return is 3'8" but i used up almost 10' of 3/4" pvc.The sump gets bubble and everything else stuck on top of the water.No movement at all.I am prob going to buy a new overflow for 1200ghp and run hose instead of pvc for the overflow.And it has only been up since a week ago.Thanks Derrick

fishfreek 01-23-2006 09:04 PM

The two 90* elbows are your problem. If you can make those two turns with sweeps you will get much better effency. The hardline PVC or flex hose has no impact although I can see how you would use 10' of pvc if you have the return spilt. That would in effect use up twice the head height in return so thats 7' 4" and then you have your drain line of an additional 3' and some odd inches.

There is no requirement to have surface movement in the sump.

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