If you are looking forward to jumping into your nice pool, but you discover that the water is cloudy when you get there, you probably feel frustrated and more than a little angry. You don't want to jump water that looks cloudy. You don't know why it's cloudy, and you don't want to take the risk that there is a serious problem with it. What you need to do is figure out what exactly is causing the problem so that you can fix it and get back to your interrupted swim. There are several things that it could be.
One thing that could be causing your pool to have cloudy water is that the filters aren't working, are too old, or are clogged. That can be easy to check. All you need to do is go look at the filters and clean them off. Make sure that all the filter inputs are clear. If the filters themselves look old, then you need to replace them. Run the filter continuously for a day or two to see if that clears the water out. If that doesn't work, then it's time to move on to something else to see if you can find out what the problem is.
Another problem that can cause cloudy pool water is poor water balance. If the pool chemicals are all out of whack, then they can cause the water to look cloudy. The water may not be dirty, but there may be too much or too little of a particular chemical in the pool. To check this, you are going to need to get a pool water testing kit. There are different kinds of kits, depending on what kinds of chemicals you use in your pool. Get a kit that works for the chemicals and test your water. The test should come with instructions which will tell you what the results should look like. If you have too much of a particular chemical, you may have to partially drain your pool in order to put new water in to dilute the chemicals. You should retest every couple of hours if you have to do that; that way you don't go too far the other way.
No one wants to come home to a cloudy pool. If you have come home to exactly that, then there are things that you can do to try to figure out what's going on. If you don't feel like trying to troubleshoot it yourself, you can call a pool service to come check it out for you. Contact a pool winterizing service for more information on upkeep for your pool during winter.