No experience here, but I think about this as well. Not as often because I only have a 10 gallon tank right now, but I still do. The DIY and the automation is almost more interesting to me than the planted tank itself.

I would hate to use a python if I had a larger tank, specifically becuase of the wasted water. It seems to me that there must be a vacuum style pump/motor out there that could pull the water (even across 50') through 1" or 1 1/2" tubing to your sink or drain. I mean if a wet/dry vac can suck up water through 3" or better plastic hose, I'm sure there is a pump that can do the job - even if you have have to wire it up yourself. I'm sure it would be more expensive than a "hobby" pump, but would be worth the "standing around" savings to me.

Ya, I'm just babbling on , but it is a great question!