Yes. You can run your python into the drain. Start the siphon yourself. I can only imagine how much water your wasting doing a 90 min water change from the sink
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also you shouldn't need to vacuum sand deeply like you would gravel since most of the waste should just sit right on top. sand is rather fine so there aren't as large crevices between particles for detritus to fall through like you'd have with gravel. all you really need to do to clean the sand is skim just above it with a gravel vac.