mag7+3' PVC+SCWD = ?gph

[ultra spikey]

I just finished building a 20g sump using a Mag7 as a return pump going through a SCWD. There is only about 3' of 1" PVC going from the pump to the SCWD. For some reason, the output isnt as strong as I thought it would be. I took a short video of it, maybe someone can guesstimate how many gph this thing is pumping out. I stuck an air pump in front of the pump to suck in some bubbles to show the flow.

 

[atvdave]

Here's a good link to get some idea.

But it won't tell you how much the SCWD cut's the flow down.

http://www.reefcentral.com/calc/hlc2.php

I run 2 SCWD's in my tank. I have one SCWD ran by a Mag12, and the other ran by a MAG18.

The SCWD really cuts down on the GPH flow...

 

[ultra spikey]

cool...thanks...

...according to the link, it should be around 500gph before it hits the SCWD. And the SCWD reduces the flow by about 20%(so ive heard). So that should be about 400gph total output. I dont think it's anywhere near that.

 

[sjm817]

SCWDs are flow killers. They cut flow back a lot more than they state.

 

[RichConley]

You're lucky if you're getting 200gph. The SCWD has 3/8" ports.


redo all your calcs using 1/2" pipe, and then subtract the 20%, and you'll probably get a more accurate number

 

[reefknight]

I had a Mag 7 as a return pump plumbed to a SCWD and did not like the flow at all. I bought a Pan World 50 and get all the flow I can handle. Most time I crank it down just a tad and that is still through the SCWD.

Bill

 

[ultra spikey]

I guess my 2 options are to either take the SCWD out or replace the pump. Id like to keep the SCWD so i'll probably replace the pump. Any suggestions on a inexpensive pump? Im using a Amiracle HOB overflow rated to 600gph. I would like to have the final output at about 500gph.

 

[sjm817]

The Amiracle cant handle 600 GPH despite the rating. A Mag5 maxes it out. If you took off the SCWD, with clean plumbing and the Mag7, the Amiracle would not be able to keep up with the flow (I've done it). I would keep the flow to ~ 350 GPH. If you want to keep the SCWD, you need a pump that can handle back pressure better than a Mag. For a submersible, I'd use an Eheim 1262 and put a ballvalve on the output. This way, you could throttle it back some if the Amiracle cant keep up.

If you want to ditch the SCWD, swap in a Mag5 impeller, which will convert the Mag7 to a Mag5

 

[ultra spikey]

could I determine my GPH by filling up a 1g jug with the overflow and then do the math?

 

[sjm817]

Yes, you could do that.