Drilling cls & ols

[chadderboxx]

Ok guys I have a build thread going on also. I'm planning on drilling my allready drilled 240g system it has duel over flow with 1" and 1 1/2 per overflow it also had a 2" in the center. My though is to do a ols and cls with 2 return pumps (1 for each) the reason behine this is cls for water flow and ols for use of a sump and its allready ready for ols. So here are my plans. Input is needed good or bad. Current as it sits

Plans for drilling

 

[MrG]

Ok i'm lost.

What is CLS?

What is OLS?

and why do people drill a hole in the middle back pane? Sorry i never got that.

Appreciate the input and hope you get your input too :tongue:

 

[MrG]

I only drilled in the corner back pane/glass. But i have seen people drill the middle back and bottom even. Sorry not screwing up your thread just adding info on it.

 

[chadderboxx]

Lol ok ill explain the best I can ols ( open loop system) is when you Utilize overflows and sumps open part being its open to the air. Cls ( closed loop system) meaning there is no air contact use by larger tanks because of water flow you drill throughout the tank for return there for water movement.