Most likely it is algae.
Algae loves phosphates. Phosphates are a natural result of pollution which are airborne and are transferred into spa water carried by wind, leaves or dust. Phosphates are also found in household soaps and detergents and are brought into our spa and pool on our bodies. Phosphates are a particular issue for those using tank water.
Phosphates are quickly becoming the number one issue for spa and pool owners.
U.S. Pool & Spa News: "A high level of phosphates can make pool service a nightmare, helping spawn algae blooms at a breakneck pace. The pools on your route may be at risk because many water treatment centres add phosphate to reduce friction and preserve plumbing lines. With high-phosphate water coming out of the tap, pool service people should take a proactive approach." (Phosphate removers do not actually remove the phosphates. Instead, they form an insoluble molecule that becomes trapped in the filter. Thus, make sure to clean your filter after using these products).
How to know if I have a high level of phosphates?
Other than noticing an increase in sanitiser use, the only other way to know that you have a high level of phosphates is to test for them with phosphate test strips.
Note these test strips are not accurate on hydrogen peroxide based products such as Poppits and Poppits Sanosil.
How do I get rid of Algae?
One of the traditional ways to treat visible algae has been to “shock” the pool with massive doses of lithium or chlorine. This is not only harmful to the environment, the spa headrests and jets, but is also potentially a health hazard. Besides this, the effects are very short lived, as these products are not true algaecides. If algae are present, even when you “shock” treat with Poppit Quick Fix the same thing occurs.
These methods tend to oxidise the algae but in doing so, a portion of the phosphate contained in the “dead” algae is released back into the water, (as the algae die in the filter). In mild cases, using 30 ml/ 1,000 litres of water of Poppit Pool & Spa Complete Maintenance followed by thorough and frequent cleaning of the filter cartridges with Poppit (phosphate free) Filter Cartridge Cleaner will not only remove the problem, it is an extremely effective preventative.
It is recommended that Poppit Pool & Spa Complete Maintenance is used every 3-4 weeks and filters are cleaned weekly. In cases where the algae have established a hold, It is recommended that pool & spa owners tackle this growing problem with a two-pronged attack as a preventative measure:
Treat with a phosphate remover and algaecide that is powerful enough to control all strains of algae! Pool Poppit 3 month algaecide is considered by most professionals to be the strongest. This is the only algaecide compatible with Poppit Spa Sanitiser and Poppits Sanosil. Follow instructions on the label 30 mL / 1,000 litres is generally sufficient to kill the algae and will clean up the spa within 48 -72 hours. This will provide protection for the life of the water in the spa.
Make sure your spa filter cartridges are under 12 months old and make sure to clean you filter cartridges thoroughly with Poppit Filter Cartridge Cleaner. Read about spa filter maintenance here.
Poppit Filter Cartridge Cleaner does not contain phosphate, sulphate or nitrate as most do. The only cartridge cleaner that can make that claim is Poppit Filter Cartridge Cleaner.