Cloudy pool after rain - sometimes this can be really infuriating. You were just swimming in your nice clean pool and along comes one of those bad summer rain storms. it is literally raining cats and dogs and your pool is about to overflow and leaves and branches clog the skimmer and overwhelm the pool cleaner.
We have all been there - the only thing to make it worse is when you notice that your pool is cloudy after rain. With a rain storm, any number of contaminants can be washing into your pool – acid rain, pollen, insects, tree droppings, dust, sand and even phosphates.
Any one or combination of these things in rain can make your pool cloudy. If everything else is good (water balance, chlorine level, filtering) and now you have this cloudy water from rain problem - not to worry - we can fix this.
When I know a storm is coming, I always make sure my pool is balanced just before the storm hits and run the filter pump throughout a rain storm. It's important to keep the water circulating and filtering. In case of flooding however, shut off the pump if there is any danger of it being submerged.
If you have had a pool for any length of time, you probably already have your trees cut back so when stuff falls it will not land in the pool, but take a look out the window as the rain begins to fall, to see if you need to trim some branches (later). Overhanging branches will wash their leaves clean, right into your pool, washing off all sorts of particles and debris.
Make sure you have chlorine in the pool during a rainstorm. If I have not shocked my pool in a few weeks, I usually shock the pool before the storm and sometimes also afterwards pool shock is also needed. A dirty rainstorm can deplete your chlorine level, making pool water hazy.
I always rebalance the water after a heavy rain. Living in the northeast where the average rainstorm has a pH of about 5.0; after a real soaker my pH level drops about 2 clicks, and my alkalinity also drops 5-10 ppm. Cyanuric acid will also be diluted by heavy rains over several days, and you may notice a decrease in hardness, because rain water is very soft, and only contains dissolved solids it picks up on its long fall through the air.
Another thing to check in your yard, make sure you do not have rain water draining into your pool. I had a customer a few years ago, he was getting rust particles in his pool. I asked him to send me some pictures of the pool. When he did, I noticed the pool was really close to the house. The gutter was broken near the roof (really old and rusty), and was draining into the pool. Needless to say that was where the rust was coming from.
Phosphates are another problem when mulch beds or planters overflow into the pool, like sometimes happens to my pool. Any small amount of dirt, mud or dust can contain thousands of ppm of phosphates. Phosphates will breed algae, but the water can start by getting cloudy at first. I test for phosphates once a month and I add a capful of Phosfree every week. If I know that a big storm is coming I make sure I add it just before the storm.
Rain can also raise your TDS level. I know what you're thinking - "rain has zero dissolved solids, it's like distilled water, so how can it raise TDS?" As the pure rain water falls through the air, it absorbs pollutants, dust, mites - not very much, but it does bring some solids with it as the rain hits the pool. Total Dissolved Solids the total amount of dissolved matter in your water, all the junk that has landed in the pool as well as any chemicals that you have put in there. All the dirt, dust, phosphates, chemicals anything that actually lands in the pool water. If the TDS is above 2500, the water can become very cloudy.
In summary, a cloudy pool after rain is frustrating, but after the rain but you can usually clear the water really quick. Shock the pool, run the filter system, make sure your pool water is balanced are the first few things I would do. You may have to backwash if the filter pressure gauge rises as it fills up with all the junk brought in by the rain. If you still have cloudy water the next day, check the chemicals again and add a pool clarifier to help out the pool filter.
SPP Pool Expert