overflow flow
 

Is there any way to calculate approx how much flow my overflow will produce?
I am using a Hoffer gurgle buster type overflow piping, with 1" pvc passing through the bottom of my tank and dropping straight down into my sump. I have no elbows or reductions.
I am trying to decide if a Mag7 will be enough for a return pump, I dont want to overdrive my overflow. The tank is only a 25gal cube so I am not going for huge flow.

There's a bunch of calculators on RC for this:

Head loss calculator:
http://www.reefcentral.com/calc/hlc2.php

Drain/overflow size calculator:
http://www.reefcentral.com/calc/drain.php

Nice summary of pumps
http://www.reefs.org/library/pumps/

I have my sump connected to my tank, finally.
I picked up a mag7 for a good price, but I dont think it has the flow I am looking for.
The headloss calculator with a mag7 and as close as I can get plumbing figures entered gives me approx 450gph. Of course the headloss calculator can not include an SCWD. The pump has no problem pushing the water up the less than four feet to my tank, but it just doesnt seen to have the umph I am looking for.
My plumbing consists of 1" pvc with a 45 degree elbow, into a ball valve into another 45, then up into the scwd, because of the 3/4" ID soft tubing required to mount the scwd the flow gets reduced. From the scwd the 2 outputs hang over the tank with 90's and then 90 again into the tank.

When I subed in two 90's instead of my 45's in the headloss calculator, my flow numbers actually went up about 20gph.
I am not happy with my current plumbing setup. I made a few rookie mistakes, so I may rebuild the return line with some 90's. But even with the extra 20 gph, I dont think I will be happy with the flow.

I think I will pick up a mag9.5 which should give me more than enough flow. The calculator gives me 742gph with the same setup as the mag7.

Well this may help you figure out what you need, although its too bad you already got the Mag7.

http://www.3iqventures.com/literature.html

Thanks for the link. Was a big help in determining my approx Gph.
The Scwd is switching in the 7-9 second area, which according to the chart is in the 400gph range. (my timing method may also be flawed)
This is actually more than I felt I was getting. If you put your hand near one of the outlets, the water flow past your hand seems very weak, when compared to my Seio 620 which is rated at 620gph.

I believe the mag9.5 will work perfect.

I decided to go with a Rio 20HF return pump, it puts out excellant flow. I do believe my plumbing set up is limiting my potential flow, and I just dont like the way I did it. So I will be replumbing my return.
Has any one tried or know of a good place to pick up Spaflex or similar pvc tubing? This could elliminate many unnecessary 45's and 90's.

Or should I just use 1" vinyl tubing?

In Alberta
Terasen Waterworks
9716 40th Street SE
Calgary, AB T2C 2P3

Tel: (403) 203-4100
Toll-free: 1 (800) 242-3176
Fax: (403) 203-9231

I'm in Vancouver, BC and the Terasen Waterworks here had it. They have LOTS of plumbing parts (cheaper than the other retailers too).

HTH.

Another place to try is "Western Pump" on 42nd Av - that's where I get my flex PVC when I need some. I haven't checked out this Terasen Waterworks, will have to check them out (if you go there let us know how it goes).