Flow Problem

[rjyj]

Ok so I am having a bit of a problem right now. I have a 75gal tank that I am looking to get around 20X the turnover. I have a 10Gal homemade wet/dry sump. I bought a mag9.5 for my return pump and made my own overflow box. Right now i have one over flow box with 3/4in PVC pipe as my Utube and 3/4in pipe going to my sump. I then took 3/4 in pipe to a T and then have 2 return lines on either side of the tank from the sump that is also 3/4in. If I add up my head I am looking at 3ft on side and 3ft on the other with 3ft to the T. Now do I also in the horizontal piece in to the head. Either way I should have atleast 8ft of head which then makes my return pump pushing about 600gph right? My over flow box is using 3/4in pipe which has a max output of 300-60gph. So everything should equal out right.... well it doesnt. my pump pumps to fast and my overflow cant keep up unless I barely open my ballvalves on my returns. So what should I do? Should I increase my overflow box to 1" pipe and leave my return at 3/4? If I were to make 2 3/4" utubes would my single 3/4 in line be able to handle it? Sorry about the rambling and thanks in advance for the help.

 

[turningtim]

First, everything that is in the return line will add to head. Valves, couplers, unions, T's, elbows, vert and hort distance, along with dia of the return pipe itself.
Your flow will be whatever the smallest dia of your drain. So adding another U won't help b/c you're draining with just a 3/4" from the OF.
A 3/4" drain will only drain 300gph, 1" will do 600 gph.
So , if you are shooting for 20x w/o a bunch of PH's in your tank the you should have an OF that will handle what the pump will put out. I have almost the same system. I run a DP 900 and have 2x1" drains and is returned with 2x1" returns.
You also must consider the linear amount of the OF itself. Just b/c you put 2x1" drains doesn't nessasarily mean that the OF will drain the water going in to it.
Goggle Head loss Calculator. It will show a place (--) that will give you the Calc's for linear dims of the OF and head loss on the system with the pump that you are using.
HTH
Tim

 

[turningtim]

Mag 9= 3/4" return, 6' vert, 3' hor, one ball, 2 exits, 1 intake= 535gph
Same with 1" returns=634gph
535 needs 8" of linear inches of OF with 1" drain
634 needs 10 inches and just over a 1" drain
There has got to be more head b/c thats w/o knowing how many EL's and T's in the system.
HTH
Tim

 

[rjyj]

Well according to the calc my flow is at 453gph. Then using the other it says i need 7" of linear inches with a min of .88 diameter. So with that in mind, what is meant by linear inches of an overflow box? I converted to 1" pipe to my sump and still cant open both return lines all the way, I am wondering if I might have some air in my PVC U-Tube that I made out of 1" pipe also which might be why I am not getting all the flow that I need. Any other ideas as to why this is not working out. It is really starting to get discouraging. I have been fighting with this tank for about 2 weeks and still not near setup.

 

[ibew]

make sure your over flow doesn't have any air in it either if you have an aqua lifter make sure that is running up to par mine just slowed down on me after 2 years had to get a new one the overflow would not catch up to the pump it took a couple of days but you new there was something wrong just something to look for

 

[turningtim]

Linear inches of OF means that the number of inches that the water has available to travel over the OF. So basically the perimeter of the top of the inner box of the OF. I would also suggest getting a pre made U out of clear plastic. Should be a couple bucks at your LFS.
Did you change the bulkhead to 1" in the drain also (rear OF box)? Or just the pipe?

 

[rjyj]

I did change the bulkhead to a 1" as well as the pipe to the sump. So I need a utube that is a total of 8" including the bends is what I take from that, well I should have it but I will look for a clear plastic U tomorrow. We will see how it works out.

 

[turningtim]

No No, not the U-tube itself. The OF has 2 boxes right? An inner box that skims the water and has the U-tube in it. The perimeter (3 sides) of the top of that box itself. SO, the front and both sides would be counted b/c thats where the water flows over it.