Display Water Level

I'm having a problem with my internal overflow. The problem is the water level in the display tank is too high. It just about touches the center brace. These photos show what my "Durso" looks like. The cap at the top of the Durso has a JG valve in it that;s open all the way. I use this valve to set the water level in the tank. It all worked fine until a few days ago. Now even with the valve fully open and a few holes drilled in the cap, the level in the tanks is higher than it used to be. Even if I take the cap off of the Durso, I would expect the water level in the display to lower but it dosen't. The sump is in my garage and water is still flowing into it. Also, if I shut the return pump off, wait a minute and then restart, the water level in the display climbs almost to the point of spilling over before it settles down. It almost sounds like my drain line might be clogged. Short of taking the drain line off, wouldn't even know how to check if it's clogged. Maybe there's a air pocket somewhere in the drain. My return line is 1" and my drain line is 1-1/4". The Durso is 1-1/2" and reduces to 1-1/4" right at the bulkhead in the tank wall. Maybe Durso is designed wrong. Can someone give me some help with this?

 

Well I agree it sounds like you are having a problem with your drain check to make sure there isn't anything caught in your overflow tube and then go down from there.

Or your pump is pushing more than your overflow can Handel

 

Also check the JG valve. I have the same set up and have found I need to clean out the JG fitting every few months. You look at it and it looks OK but then when you clean it you realize it was partly clogged with salt. Also make sure your teeth of the overflow aren't clogged with algae

J