Need Help with water level

[Maho.B]

Hello, so everything is doing great in my reef, but I have a problem with the water level. For some reason it has slowly gotten higher and is now too high to where it is somehow leaking out at the front corners from time to time.

It's a red Sea Max S 400 and I can't get the water level below the clear brace that runs along the front top. If I open the back valve to let water out of the display more, it immediately gurgles insanely loud.

What am I missing? How do I lower the water level in the display??? Thanks

 

[Uncle99]

Can you slow the pump down?
Any pics?

 

[Maho.B]

I'll try and get pics shortly. I'm currently looking at how to add the return pump as I done that. It's a vectra and it is connected to the Mobius app and there is a "dial" type controller as well. Is it correct that if I slow the return pump down the water level will lower?