Why does an outdoor swimming pool turn green after a thunderstorm?

Rating: +6

The reason for this is that lightening creates nitrogen in the atmosphere and the rain washes this nitrogen into your pool. Nitrogen is plant food and algae thrive on it, so pool water can quickly turn green after a thunderstorm, a shock dose of chlorine can help prevent this if done as soon as possible after a thunderstorm. Also use an Algaecide and keep your sanitiser levels at the correct levels.

Algae are microscopic plant life that, in the right conditions, multiply rapidly usually turning pool water green and opaque. Because algae are so small they do not become visible to the human eye until there are millions of them, so the early stages of an algae attack can easily go undetected and therefore untreated. Recovering an algae infested pool can be time consuming and expensive, which is why algae prevention is always preferable to cure.

The secret to keeping your pool algae free is to maintain the correct water balance, oxidise regularly to destroy sources of algae food and organic wastes, apply algaecide to support the sanitiser (chlorine or bromine), continuously keep a consistent sanitiser level in the water and test regularly to ensure the the correct levels are being maintained, hence the innovative BOAST pool care system we use at Professional Swimming Pools.

To get more info on pool chemicals or claim your free “POOL CARE GUIDE” please go to our Contact page.