Cyanuric acid, also known as “stabilizer”, helps prevents the sun from destroying the chlorine so rapidly. You will want to keep your level of stabilizer at around 60-70ppm (parts per million).
Pool pumps need to run longer in the summer because the pool requires more filtration. Generally, pumps should run at least 8 hours in the summer. If you have a salt system you need to remember that chlorine is only produced when the pump is running.
Most pools use cartridge filters. Manufacturers suggest that the filter element that sits inside the canister be replaced every year. We find that they are generally good for two years. With the increased demand for filtration in the warmer time of the year, this is a good time to replace the filter element because worn filters reduce the flow.