Rain and Your Pools Water Chemistry

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Rain is a good thing, right? Farmers need it for their crops, it waters our lawns and landscapes, so we don’t have too but what about the rain and your pool? We all know rain water is acidic, but how does it really effect pool water?  Well, we will tell you.


Runoff is a serious problem when it comes to your pools water. This is the quickest way for contaminants like dirt and other debris to end up your pool water. And the quickest way for your pools pH levels to change drastically. The waters calcium hardness, alkalinity and free chlorine levels will be all over the place. Although a light rain should not cause too much harm, you should still test your water levels after every shower. The water chemistry should be properly balanced always.


Rain has a pH of 5.0. Ideally your pools water has a pH of 7.4 to 7.6, and this is because the human eye has a pH of 7.5. As the rain water mixes with pool water, it lowers your pH levels. When the pH levels seep down into the 5-6pH area, this is going to cause eye irritation. A lot of peoples first reaction to eye redness or irritation is to blame the chlorine levels, but a lot of times your pH is too low.


What To Do Now?


A huge rainstorm has passed and now what? Your waters chemistry is probably diluted, and access water is spilling over the sides. You will need to drain this extra water. If you have a D.E grid, put the multi-port valve from vacuum to waste mode. This will eliminate the extra water without putting it through the filter.  Don’t forget to turn off the pump beforehand and attach a waste line or backwash hoe. Then, turn the pump back on until the water drains by one or two feet. Then, turn the pump back off again. Turn the valve to the filter position and then turn the pump on again.


If you have a cartridge filter, the process is a little different since they don’t have a backwash valve. Every system is different. If you have a hose bib plumbed into the line, then you can use that to drain the water down to the appropriate level.


Always be careful not to drain the water below the skimmer as you could run the pump dry and cause other problems. Use a skimmer to remove all debris off the surface of the water. Then run your pump to filter the water and remove all other debris particles.


Keep a water testing kit handy. Once your water level is back to normal, test your water. Make the appropriate additions to whatever chemical your pool is lacking.

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