I have an adjustable overflow, and I set mine for about 1/2 way up..maybe a hair more. But I have been trying to figure out why the water in the overflow is so high. About an inch over the durso 90. And nothing is restricting flow, and my return pump is a bit weak for my tank I feel.
Maybe the hole in the top of your Durso is to big.
I never thought of that! what size should it be? I drilled it myself a while ago and I think I used a 3/8'' drill bit
Multiple small holes work well too.
I run it low it seems to skim better
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