Pool company recommends weird levels with my UV sanitizer

[poolgal13]

Okay, no lashes with a wet noodle--but when they put my pool in last year the Trident UV Sanitizer was part of the deal. It doesn't claim to be the cure all--my pool manual says a sanitizer is always needed. But here's the weird thing--they recommend only a free chlorine of 1-2 ppm. They want the CYA 30-40 (that's fine but would be hard to keep with the trichlor puck dispenser they installed) and the TA 120-150, a little higher than this site says. The "best guess chart" on the site says I would need a minimum of 3 ppm with a CYA in that range. So do I dare keep the level that low? To me, the UV sanitizer is sort of like a "polish' for the chlorine that's doing the bulk of the disinfecting. It just might help and probably doesn't hurt. Also, they want me to use some goofy product called "Aqua Finesse" tablets once a week. I researched it since no ingredients were listed on the tub. It has "sodium carbonate" and "sodium silicate" and "sulfuric acid aluminum potassium salt dodecahydrate" What's up with that???!!!!!

[CarlD]

The only chemical I know for sure is Sodium Carbonate. It's the main pH raising chemical used by pool stores and pool companies, as pH Up! and other brands. But it's available at your grocery store as Arm & Hammer Washing Soda in the yellow box..NOT BAKING SODA! It's not expensive, about the same as Borax. But it WILL raise your T/A level further. Other than that, it's a mystery to me.

[chem geek]

Aquafinesse has surfactants for biofilm removal. The aluminum potassium salt dodecahydrate is for adding aluminum as with an alum floc. The sulfuric acid is to lower the pH while the sodium carbonate raises it and TA -- the combo causes carbon dioxide bubbling. Sodium silicate is similarly used as a coagulant/flocculant. Where did you see that these are the ingredients for Aquafinesse? They look more like ingredients for a different product. None of this is necessary in a properly chlorinated outdoor residential pool.

The TA recommendation is too high if you are going to be using a hypochlorite source of chlorine -- it should be more like 80 ppm (or 70 ppm if using a saltwater chlorine generator). Otherwise, the pH will tend to rise over time from carbon dioxide outgassing.

[BigDave]

PG13,
I, respectfully, diasgree with the notion that there is no harm from the UV sanitizer. The UV it emits breaks down the chlorine in the water. The harm is that you pay for the chlorine and the electricity to run the UV unit.

If the pool is indoors or otherwise shielded from the sun's UV it may be necessary to run a UV unit to break down combined chlorine. If the pool is exposed to the sun it gets plenty.

Please don't think I'm swinging a wet noodle - I usually just float on them.

[poolgal13]

Thanks, everyone, I've been off my computer for the last week or so. I will skip the Aquafinesse. (I found the ingredients listed when I searched for the MDS sheet). I'm so made about the UV sanitizer--it never even occurred to me that it's also breaking down my chlorine!! DUH!! I feel like I was taken for a ride because even though it was "part of the package" I know I paid for it somehow!!!! Sigh. I can always unplug it:-(

[BigDave]

Maybe ebay?