How does heavy or consistent rain affect your pool water balance and running of your equipment? More importantly, what you can do about it?

Contrary to what you may initially suspect, the most common problems caused by heavy rain are generally NOT a result of diluting the chemicals in your pool. An inch of rainwater added to a typical 50,000 litre pool only increases the amount of water by only about 1.5%, meaning dilution is not usually an issue. However, a lot of rain and consistently lowering the pool level can dilute the concentration of chemicals in the water.

It’s usually more about what comes into the pool with the rain. Rain delivers more than just water, it contains algae spores & dust, which are usually present in the air and drops them directly into the pool, and it’s these things that cause problems.

All of this material reacts with your pool chlorine and so reduces the active chlorine level in the water. Combined with this, when the organic matter decomposes it provides food (phosphates) for the growth and reproduction of algae in the water which accelerates the growth of algae in the pool.

If you have rainwater coming off your garden or deck into the pool, you also have an added source of water and debris to deal with. When rainwater and ‘run off’ enter the pool, they can change your water’s pH, calcium hardness, total dissolved solids (TDS), alkalinity, and other chemical levels as well as bringing more debris & dirt into the pool.

So, what to do?

As always, it is important that you test your water after it rains and re-balance it if necessary (always take the sample from elbow depth as new rainwater will typically sit near the surface of the water). If the Total Alkalinity of your pool water is within the ideal range, then the pH of the rainwater will not significantly affect your pool water balance.

Lowing your pool water level.

To reduce the amount of water in your pool to allow for proper skimming of the pool surface, we suggest using the following instructions if your filter has a multiport valve.

Backwash & rinse your filter if you haven’t done it recently, then lower your pool water level down the middle of the skimmer box to prevent overflowing and maintaining a proper skimming action.

1. Turn off the pump,
2. Change the filter multiport valve handle from “filter” onto “waste” (not backwash),
3. Open any valves on the waste line,
4. Disconnect suction cleaner & remove vacuum plate from skimmer box,
5. Then turn the pump back on to lower the water level,
6. Wait until the water level is halfway down the skimmer box opening (this can take 5 or more minutes) then
7. Turn the pump off,
8. Return the multiport valve handle to “filter”
9. Reconnect the vacuum plate and suction cleaner and
10. Turn the pump back on (or set time to auto).
11. Bring a water sample into the shop to balance once you’re done!

Pool going green?

The solution is to make sure that the rate at which the algae in your pool are being killed is faster than the rate at which they are reproducing. This means raising the sanitiser (chlorine) level much higher than the ideal range, balancing the pH level, adding an appropriate algaecide, clarifier and oxidiser. By adding these chemicals and running the filtration system for a minimum of 24 hours that should return the pool to crystal clear again.

Pool has gone brown/muddy

With very heavy rains, runoff from gardens and surrounding areas of the pool can add large amounts of dirt, garden soil, and even mud into a pool. This will turn the pool into a messy brown soup with the inability to filter out. This is where a floccing agent is used to bind the suspended particles together and drop them to the floor of the pool to make it easier to remove by vacuuming directly to waste.

If you require help with any of these techniques please come into the shop and speak with our experienced team or book your service online below.

Contact us to help with a rain affected pool