The lower the gate valve is the easier it will be to adjust, mine sits 1" above the water level in the sump, without an ATo you'll find yourself adjusting it as the sump level goes down as it changes the flow, also barometric pressure will affect it, all minor things but something to consider, on my 8' tank with ato I never adjust it, my 75 with baffles I'm constantly adjusting it
I usually go with a bare tank and ATo for a sump if I'm running a herbie.
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