weir overflow/sump help please

have same setup on a 50 weir pvc 1" it will only flow about 500gph ' do you have a standpipe on it? to keep from starting its own siphon?

 

does it look like this?

http://www.3reef.com/forums/i-made/nice-cheap-diy-overflow-29396.html?highlight=weir

 

I have built several weir overflows and fuges. The first thing I do is install a lift pump on the weir to keep air from breaking the siphon. This may not be a problem but keep it in mind if it becomes one.

When setting up the system, I fill the tank and let the water go through the overflow and fill the sump. When the sump is full I turn off the water. This will be the pump off water level. Then I turn on the pump and the water level will drop to the running level. This is how high my baffles from the floor of the sump will be. Then I install the baffles.

With all of the valves open, your water level in the sump drops too low, you do not have enough water in the sump. Fill the sump to a good running level. Then shut off the pump to check the sump does not over fill.

With the valves open, your water level in the tank over fills then you have a restriction in your drain to sump lines. This could be a plumbing issue. I usually install 1 inch pipe to a system like yours. Make sure if you have two lines feeding the tank that you have two lines draining to the sump.

The only thing a valve should be used for on your system is for servicing your equipment. If the flow is to much for the sump then put a tee after the pump output and put a valve on it to control the flow from it back to the pump compartment. This will slow the flow in the system.

Forgive me if I duplicated anyone’s input, I did not read all of the reply post.