plumbing questions

[BubbleHead]

It's been awhile since I plumbed a tank. I just want to make sure i get it right the first time.

 

Here is what I have,

 

90 gallon reef ready drilled on bottom. The dover flow bulkhead is 21/2" (od)and the return is 11/2" (od).

 

Return pump is a Mag 12 in a 20 gallon sump.

 

Which of these lines needs a valve? the valve on the return is easy as it's small amd I have a bunch of them, but a valve on the overflow would either be big or the line would have to be reduced and then flow is cut down.

[Scott_LM]

You do not want a valve on the overflow unless you are doing a beananimal design or something similar where a siphon is created. In a typical gravity overflow system flow should be unobstructed, even reducing the 90 degree elbows helps. A valve on the return is a very good idea to allow you to scale the flow up or down depending on the need,

 

-Scott

[Coral Hind]

I agree with Scott, only a valve on the return from the pump is needed.

[BubbleHead]

that's what I thought.