Solar-powered Algae Control

[Bugman1400]

My neighbor has a device that looks like a frisbee that floats in his pool, is solar powered, and has an electrode that sticks down into the water. He claims it controls algae using a sacrificial electode. To me, it just looks like a screen with blue goo on it. Anybody know what this device is and how well it works?

[quantumchromodynamics]

It is most likely a device that puts copper and/or silver ions into the water. I recommend against such "ionizers". They are a waste of money.

[AquaclearNZ]

It is most likely a device that puts copper and/or silver ions into the water. I recommend against such "ionizers". They are a waste of money.

Will be a floatron - commonly known as a waste of time and/or money

maintaining correct chlorine level and reducing phosphate will work just as effective. and be a lot lighter on the wallet

[Bugman1400]

It is most likely a device that puts copper and/or silver ions into the water. I recommend against such "ionizers". They are a waste of money.

Will be a floatron - commonly known as a waste of time and/or money

maintaining correct chlorine level and reducing phosphate will work just as effective. and be a lot lighter on the wallet

That's it. My neighbor claims that it allows him to keep his Cl level much lower because the Floatron prevents algae growth. He only uses a few pucks a week. How long do these Floatron's last?

[chem geek]

It is true that a supplemental algaecide (which copper is) can let one use a lower chlorine level for sanitation (killing bacteria, etc.) since algae growth is inhibited, but there can be side effects. Specifically, metal ions can cause staining of plaster surfaces, have water turn green (for copper) and blond hair get yellow-green. This can happen if the concentration of metal ions gets too high or the pH rises too much (high pH precipitates metal ions). Unfortunately, there aren't inexpensive metal ion test kits to let you monitor and control the metal ion level and the level required to kill algae gets close to the level that causes staining if the pH rises. If you have a vinyl pool and regular water dilution, then the risk of these side effects is lower.

Use of a phosphate remover or weekly PolyQuat 60 algaecide would also work in a similar fashion but without staining side effects. All of these "alternatives" are extra cost.

Keep in mind that when one is using Cyanuric Acid (CYA) in the water, that the active chlorine concentration is already very low. When the Free Chlorine (FC) is at least 7.5% of the CYA level, algae growth is prevented by chlorine alone and that this is technically equivalent to around 0.06 ppm FC with no CYA -- a very low level already. If you use a lower chlorine level, then disinfection rates are slower as well, though in residential pools this is less of an issue since person-to-person transmission of disease is less likely and one sick person won't infect dozens of others as in commercial/public pools.

If your friend is using "pucks", then that's Trichlor and will build up CYA over time which is why algae can grow unless he uses a supplemental algae killer. For every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm. Even at a low 1 ppm FC per day chlorine usage/consumption, continued use of Trichlor will result in increasing CYA by over 100 ppm in 6 months if there is no water dilution. If chlorinating liquid or bleach were used instead (or most of the time), then there would be no buildup of CYA and algae growth would be prevented using chlorine alone.