High alkalinity, which is above seven on the pH scale, is the result of improper chemical levels in the pool. Each chemical you use to keep your pool clean has a different pH, so a ratio that isn't optimized for your pool size may cause the number to go above 7.8, the high end for a good pH range in most swimming pools.

How often you should add water to your pool depends on how quickly the water evaporates. Keep an eye on your skimmer box, if you have one. Top up the water in your pool if you notice the water levels are lower than the bottom third of your skimmer. This helps prevent damage to your pump. 

Replace all the water in your pool every five to seven years, depending on how often you use your pool, the weather, and whether or not you close your pool for the winter.

It depends. Your pool might need chlorine every day if the water is exposed to direct sunlight and you use your pool frequently. UV light and constant use will deplete chlorine levels more rapidly. Test your water regularly to see where your levels sit and adjust accordingly. Generally speaking, most homeowners need to add chlorine following a water chemical test about one to three times per week.

It’s okay to leave a pool pump on 24-7. In fact, running it continuously has big upsides, including consistently distributing chemicals, keeping a steady pool temperature, preventing algae growth, and keeping pool water clean. However, there is a tradeoff—operating a pool pump around the clock increases energy costs and can take a toll on the pump’s longevity. If you want to run your pool pump all the time, invest in energy-saving equipment like a variable-speed pump.