I think your first decision is on how to keep from overfilling the tank with such a system. An overflow drain is, in my opinion, the best way to do it, and drilling the tank makes that a very easy installation. If you drill the back or end of the tank, you can just put an elbow fitting in it, pointed up, with the top edge at the desired full level for the tank. You need a strainer on that if you have small fish.
Once you have the overflow drain, you just open the inlet valve to change water, letting the water drain as it fills. You need to run the water for a fixed time, based on the flow rate you have. When I did this I kept the water on constantly, at a very low flow rate, so water barely trickled out the drain 24 hours a day. I used a drip irrigation flow restrictor to set the very low flow rate I wanted. This was a very successful installation for me.