The chemicals need to be checked every week due to the fact that chemicals only last 7 days. With a high pH, chlorine can only be effective at a 10% rate. If the alkalinity is low or high that can have an effect on how the sanitizers perform. Monitoring the TDS level will have an effect on balancing the water which is different from sanitation, although related. If you have a salt system, the cell needs to be monitored due to the calcification that occurs. This will have a direct effect on the sanitation output. If you have a sand or DE filter, these need to be backwashed/cleaned on a regular basis so you get the maximum filtration that is needed. Checking and emptying out the skimmer baskets and pump baskets are crucial. If the debris gets through these then it can clog the pump and the circulation will be at a minimum and potentially cause big problems. Brushing the walls and tile line will help eliminate algae problems and it will also keep the plaster nice and smooth.