Plumbing question

[NewPhishGeek]

Hi - I will be setting up a 29 gal tank with a 10 gal as a sump. I purchased a Mag 7 pump a a real good price and realize that it may be a bit of overkill for a 29 gal tank. As you can see from the drawing (a paint quickie) I have a return line going back to the sump, I thought that would keep from restricting the pump too much. I was thinking of adding a UV unit to the return line, is it worth it? Oh, the overflow is a U tube type rated at about 500 gph, I figure that with a 3' head the Mag 7 would be about 500 gph. The drain line will be 1" what should the return be 1/2" or 3/4"?

 

[fishfreek]

I was thinking of adding a UV unit to the return line, is it worth it?

No. If you want a UV plumb it seperate. UV is most effective at low flow rates and you dont want to have to run your return at the flow rate to get optimal kill on the UV.

Plumb the return line the size of the Mag 7 outlet. I belive thats 3/4" but dont count on my sayso.

Whats the valve on the drain for?

Only thing I would add would be a one way valve just below the tank side valve on the return portion. This is a valve that allows water to flow only one way. So in the event of a poweroutage the return wont backsyphon the water into your sump till it gets to the spraybar level. The oneway valve will close keeping water from flowing back.

 

[NewPhishGeek]

Good idea on the check valve for the return line.

The two valves on the pump return would be for flow control, I could reduce the flow to the tank and open the valve for the return to the sump and not increase the back pressure on the pump too much.

As for the UV, it would not be on the drain line from the overflow but on the pump return to the sump (where it is marked return on the diagram)

Thanks for taking the time to respond!

 

[loganj]

My thoughts are that by the time you go through all the elbows and the spray bar, you're not going to get anywhere near 500gph from the Mag 7. You can figure an extra foot of head for each elbow in the return line. The spraybar will also decrease flow a good bit depending on the design. Your return line from the pump to the sump is a good idea, but I don't think it'll be necessary. If you do use it, I would make sure the outlet is well under the water surface to avoid making zillions of bubbles. I'm going to offer an alternative idea to the check valve because I don't trust them. My theory is that it'll work fine until you leave for a two week vacation...that's when it will fail...Murphy's Law. Drill a hole in the return line just below the water level in the main tank. This will serve as a siphon break in case of a power/pump failure. When the water level reaches the hole, it will let air enter the line and break the siphon. I wouldn't bother with a UV sterilizer because I don't think you'll need it. I'd spend the money on a top quality skimmer instead. JMHO.