Auto water top up for fish tanks

Putting in temporary auto water topup for fish tanks. Because of the high level of stocking its important to keep the toxins down as much as possible so we have plants doing a great job. But it is surprising how much water they drink, and with evaporation high due to the temperature it has become more important to get this job done, we have a small leek but rather than try to fix it we are using it to drain away water as part of our good housekeeping and water replacement program.When everything has settled down we will be using rainwater for the topping up process. The air quality is very good so we won’t be suffering pollution problems