Nice set up. I tried doing that but after my sump drained the refill flow from my 1/4" couldn't refill fast enough and my sump went dry. Now I have to do it manually anyway by shutting off the tank pump before the sump refills back up.
That means you had the pump on too long. You need a digital timer so you can control it down to the minute. When it gets close to the minimum water level your sump needs, have it shut off.
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