Green Algae Growth

[nogueras]

Having had problems with green algae (mainly due to high cyanuric acid), I wonder if anyone knows if algae can grow in pure distilled water? I believe it will not. The reason I ask is that maybe a dose of green algae is good for a pool now and again as it may thrive on the impurities introduced to the pool over many years. My theory is that the following the treatment to remove the algae, i.e. shocking and floccing, the algae is removed, containing (hopefully) all those contaminants.

Since experiencing this my pool has been perfectly clear and 'shiny', its very best for many years.

Just a thought, has anyone else experienced this?

[chem geek]

No it will not grow in distilled water because there are no algae nutrients for it to grow, such as phosphates and nitrates and if the water was not exposed to air then there aren't even carbonates in it.

As for why your pool looks better after shocking and floccing after you got algae, it looks better not because the algae was there but because you shocked the pool to higher chlorine levels which oxidized more chemicals and perhaps the floccing helped if you had fine particles too small to get caught in your filter. The algae was not the benefit here and would primarily use chemicals that wouldn't cause water quality issues -- namely dissolved carbonates, phosphates, and nitrates.

[ronnyaderson]

Algae doesn't effect swimming pool water, but the surface on which they accumulate becomes very slippery. Some prevention like sensitizing pool water and giving it a shock treatment by adding more chlorine can stop the growth of algae.

[chem geek]

If one maintains the proper FC/CYA minimum ratio then one can prevent algae growth regardless of algae nutrient level and never need to shock a pool. See the Pool School for more info.