Hopefully by this time of the season you have all your leaks fixed and any green stuff in the water gone and taken care of. This entry will go over a few water chemistry basics to keep in mind.
Chlorine, in most pools this is what we use to keep the water clean and safe for swimming in. You want to keep the levels somewhere between 1-3 PPM. This is a comfortable range for people to be in. Any lower and you run the risk of algae forming, any higher and it may not be as comfortable to bathe in.
pH, this number is acceptable when it falls in the 7.2-7.8 range. Ideally 7.4-7.6 is perfect. The pH of your eye is about 7.5 so you can see why 7.4-7.6 is ideal. Also this is typically the range where most types of chlorine work pretty well.
Alkalinity, perhaps one of the more important chemistry factors should be anywhere from 80-120. You can think of Alkalinity as the anchor holding the pH in place. If the Alkalinity is good your pH, in most cases, will also be good. If your Alkalinity is low your pH will fluctuate greatly which will cause other water problems, some very costly especially if a heater gets eaten by aggressive water.
Calcium Hardness, this is often overlooked but shouldn’t be. The ideal range is 200-400, that’s where the water is “happiest”! Some places this number is low and can be increased by and some calcium chloride. Other places where this number is high, not much can be done. When this number is high the water will try to deposit excess calcium on pool walls, inside of pipes/filters, and can be seen sometimes where pump plugs or fittings get a white crusty substance. If the water is low in calcium it will become aggressive and try to take it out of the vessel that it is contained in. That means with a plaster pool you may see etching and the pool surface becoming rough. In a liner pool low calcium will shorten the life of it.