Need help deciding what to use for returns

[number1gsxxr]

I have two 3/4" threaded bulkheads that go through a SCWD for returns in my 4' tank. I tried using penductors on the outputs but unless I turn my return pump up all the way, I get a very slow switching time between them. The problem if I turn my pump up all the way is that I start pushing way to much water through my overflow. The overflow can handle the GPH but it sounds like Niagara Falls. I've tried it without the penductors and I get a much better switching response. I think the backpressure of the penductors affects the SCWD too much.

So my question is: What should I use for the outputs of the bulkheads? Should I just use strainers so snails and things don't get into the plumbing? Or should I use some Locline and point them in different directions? If I use Locline with some kind of nozzle, won't that put backpressure on the SCWD (but probably not as much as a penductor)?

 

[JohnK]

I'd just use locline. I wouldn't worry about snails getting in there because the SCWD will switch back and blast them out quick enough.

And yea, I wouldn't use penductors with a SQWD. Penductors are really only happy on a fairly big pressure pump. Said pressure pump would not be well matched to the SQWD.

 

[number1gsxxr]

Yup that sounds about right. When I was pushing about 1000GPH through the SCWD I was only getting a 3 min switch while using penductors.

 

[JohnK]

You weren't really pushing 100gph then What kind of pump? I bet the penductors were totally killing the flow rate.

I have an iwaki pump rated for 420 GPH on a SCWD and it switches about every 90 seconds.

 

[number1gsxxr]

3/4 or 1" SCWD? I'm sure with all the bends in my plumbing I was probably getting much less than 1000. But my pump supposedly goes up to 1,100gph at 0' head? Eheim Compact+ 5000 pump.

Here's a chart for the 1" SCWD

Switching rate---Seconds
30 seconds---3500
55 seconds---1800
80 seconds---1200
120 seconds---900
155 seconds---720

 

[JohnK]

Ahh, I'm talking 3/4" SCWD.

Either way though, I don't know how much water that ehiem is moving while trying to drive a couple of penductors. Eheims are fantastic pumps, but I don't think they are designed with pressure applications in mind.

According to those numbers you posted, it's probably pushing less than 700 gph.

What do you think of that 1" SCWD anyway? I'm considering one for the future.

 

[number1gsxxr]

I've only had it running for about 2 weeks now so I can't say how it will hold up over the long term. From reading on other forums it seems like their customer service is good should I have any problems with it. I like the fact that you can open it up and clean it and the fact that the unit doesn't have hose barbs. But I think it would work a lot better without being forced through 3/4" bulkheads though. I probably should have gone with the 3/4" unit or drilled the holes in my tank larger. I was kind of hoping for a faster switching time, but without the penductors it's a little better.