I have a 125 gallon set up and I'm using an overflow box. The overflow goes to a wet\dry filter which has a mag 5 pump in it. The mag 5 pumps from the wet\dry to an Aqua C EV 120 skimmer which is housed in a 10 gallon sump. The sump has a mag 7 pump to return water to the tank. I have a ball valve between the mag 5 and the skimmer to regulate flow. Here's the problem I can set the ball valve so that everything seems stable for 3-4 hours however after about and aditonal 6-8 hours the wet dry filter is almost full. If I open the ball valve further the mag 5 out runs the mag 7 and the wet dry filter runs dry. Any suggestions??? A side note this is an upgrade project because of seam that let go on my 55 gallon acrylic tank so there is livestock in the 125.