Why has my hot tub water turned green?

Why has my hot tub water turned green?

If your water goes green it is normally an issue due to lack of chlorine. 

Issue: Low sanitizer level.  Solution: For a spa around 1000L of water add about half a cap-full (cap on top of bottle below) and the spa should move to a better water clarity within 24hrs.

https://www.canadianspacompany.co.uk/collections/essential-chemicals/products/chlorine-granules 

If the water moves clarity moves in the right direction but not fully clear repeat the adding half a cap-full of chlorine granules until the water is perfectly clear.

If adding additional chlorine does not bring the water clarity back or moves it in the right direction but still the water is not fully clear, then we can deduce that the cloudiness/green tinge to the water is not due to lack of chlorine but that the particles are thin enough to get straight through the filters therefore on a spa around a 1000L we would advise about 4 cap-fulls (again referring to the cap on the bottle below) of spa clear which will clump the particles together to make them bigger so that the filter can catch them.

https://www.canadianspacompany.co.uk/products/spa-clear-clarifier-and-flocculant-500ml 

Again within 24 hrs of adding the 4 cap-fulls the water should be noticeably clearer.

Finally if you have run through a combination of the first two above and there is no change there should be dissolved copper or iron in water from the watercourse. At this point check the pH level using a test strip below and adjust either up or down accordingly using pH up or pH down.

https://www.canadianspacompany.co.uk/products/test-strips-x-50

 

https://www.canadianspacompany.co.uk/products/ph-up-750g 

https://www.canadianspacompany.co.uk/products/ph-down-1kg