On the other hand I did took care of a pool for a while, it was in a villa that my in laws owned.

We did a few things that helped lowering the maintenance cost and the pool was pristine.

First thing is a salt chlorinator. It keeps a constant (low) chlorine level so the pool stays clean, there is no more chlorine smell and you only need to top up salt after too much rain.

Then we were using hardware store muriatic acid to bring the pH up and baking soda to control alkalinity. We still went to the pool store to get productd for the calcium hardness and cyanuric acid.

The last thing is a bit more involved but this is what made the biggest difference on the bill is to replace the pump with a DC pump directly connected to refurbished solar panels, no batteries, no inverter. This way when there is a lot of sun the pump is running a lot, a little sun and the pump is running a little.

It's perfect since the amount of algae development is proportional to the amount of sunlight. There is almost no electronic in the system, just a extremely reliable DC pump and solar panels that can last for decades, I found that to be a great low-tech solution.

However we were in a tropical country, I have no idea if this would apply in another climate.