An easy way to know whether your sand filter has enough sand is to check how full the filter is and what the sand looks and feels like. The filter container should be two-thirds to three-quarters full of sand. Look for interior marks indicating the ideal sand level. If you put your hand into the sand, it should flow through your fingers without clumping. The filter pressure gauge is also an easy indicator—the right amount of sand leads to normal pressure, while too much or too little sand can cause high or low pressure.

The amount of time your fiberglass pool project will take depends on the size of the pool and whether you are installing add-ons like decking and landscaping. Overall, you should expect it to take four to six weeks to install. If you are dreaming of summer pool parties, make sure to budget enough time into the installation schedule to have your pool up and running in time for the swimming season.

No, shock and chlorine are not the same thing, though they are related and both are used for pool maintenance. Regular chlorine, often in the form of tablets, is a sanitizer used for routine, day-to-day maintenance to keep a steady chlorine level. Pool shock, however, is a highly concentrated dose of chlorine used periodically for a more intense cleaning. It rapidly raises chlorine levels to fix issues like cloudy water or algae growth and also eliminates chloramines, which are byproducts of regular chlorination. Because their purposes and concentrations differ, they are not interchangeable, and proper pool care typically requires using both.

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.