Another plumming question? PLEASE HELP!!

[snaza]

How do i work out what size piping for my weir and return pipes. how do i work out what size return pump also. I'm very confused, does it have to be exact size to pump ratios? if its not will it over flow or something. how do i stop it overflowing if the pump in my weir gets blocked?

my tank is 90Gal(360L) and my sump/fuge it 20G(80L)

thanks

 

[mg426]

90 gallons is going to want between 270 and450 gallons per hour through the sump. 3 to 5 times tank size. The overflow will only provide as much as the return pump is providing to the tank.
if your overflow loses siphon your pump can only pump as much as is remaining in the sump. This is hard on the pump but will not overflow your tank if you have the levels set correctly and have tested the system to be sure. On the other hand a loss of power/pump failure will cause the level to rise in your sump untill the overflow teeth are uncovered. Once again this will not cause a flood provided you have enough reserve capacity in your sump. Look on the home page for the overfow drain size calculator. When you have figured that all out choose a pump that will not exceed the max flow rating of the drain size. Another good idea is to use a siphon break in your return line/s. this is a 1.8th inch hole that is drilled in the return line 1/2 inch below the water level in your tank. In a loss of power situation the water will drain into your sump through the overflow and back through the return line untill the siphon break is uncovered . The return line will then suck air and the siphon will stop. It takes a bit of figuring out but when its all said and done (and tested several times) it is very reliable.

 

[Mr James]

I'm using a Mag7 with my 90g and it does just fine.