Cloudy green spa water is actually not a very common problem. It is caused by algae growth, and a well-maintained spa will usually not have this issue if only because spa water heated to a typical operating range and kept there is not very hospitable to algae (it doesn’t like the heat).
However, if you do get algae bloom, the usual recommendation is to shock the tub based on the instructions in your chlorine or bromine based product. Run the pump for 3 or 4 hours following the shock treatment, and then clean the filter. If the infestation was severe, you may have to repeat the sequence several times.
Prevent Green Spa Water with an Ozone Maintenance Program
The usual cause of algae in spas is insufficient sanitizer. The sanitation routine recommended by DEL Ozone will prevent algae blooms.
- Install and maintain a spa ozonator properly sized for your hot tub. We recommend running the pump at least six hours per day to ensure the water is circulated through the ozonator. If you use the spa heavily, run the pump more often. Older spas with continuous circulation pumps spend more energy, but they yield high levels of sanitation.
- Maintain a background residual of about 0.5 to 1.0 ppm chlorine, again depending on the bather load. Maintaining some free available chlorine in the spa water will ensure that algae cannot get started in the nooks and crannies.
- Test the water regularly to maintain the proper pH (7.2- 7.6) and total alkalinity balance (60 to 180 ppm) to help the residual chemicals work most effectively.
It is important to note that the ozonator cannot stop an algae bloom once it gets started. Algae attached to the spa walls will not encounter enough ozone to destroy it. Ozone does kill algae, but the ozone injected into your spa dissipates very rapidly in encounters with other contaminants, and it decomposes rapidly into ordinary oxygen. Therefore, if algae get a foothold, you have to go to a chemical attack.
It’s better to avoid the problem. Keep that ozonator humming.