One caution on Venturis - they are not all created equal.
The ones they call venturis in the tiny aquarium power heads are not, really just a mixing spot where the water moving past the air entrance port causes a low pressure and "sucks" in some air.
These will stir the water and help with surface oxygenation, but do fuck all on direct water oxygenation. I've tested this multiple times because I did not believe it.
Real venturis like the ones used for commercial purposes have a high pressure zone on the output where the water and air mix under pressure. This is what causes DO to go up.
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That is a proper venturi.
These are as effective as farting in the tub
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