Where Was I

[JFS]

I have a 18K plaster/gunnite pool in SoCal, which I sub contacted out, owner/build, about 25yrs ago.

I have always maintaned my own pool and have never had any major prob. This is prob due to fact I routinely drain 80% of my pool, every 3 yrs. I was having some minor algae prob about 6mo ago and had pool store check water. Said phosphates extremely high, what the hell was a phosphate???

I found this forum and have been on it daily ever since.I was from old school, checked TC thought 2 was ideal, checked PH, ocassionaly checked TA. Where was I ??? When did this new water chemistry science come into being, I feel like an idiot, which wouldnt surprise most people, and wonder how many people are just as unaware as I was, including those working in pool stores and servicing pools.

I also have to get some baking soda to raise my TA from 80 to about 100 (I use tabs). Calculator says 5lbs raises about 10 pts. Does this sound right or am I reading it wrong? Where is best place to buy large boxes baking soda, supermarkets have just those small boxes.

Thank God for Forums-Joe

[chem geek]

Joe,

Phosphates are essential nutrients for algae, along with nitrates and some form of carbon (such as carbonates or carbon dioxide). Though their presence will allow algae to grow, having a Free Chlorine (FC) that is at least 7.5% of the Cyanuric Acid (CYA) level will kill the algae faster than it can reproduce even at high phosphate levels. I have 2000-3000 ppb phosphates in my pool, for example -- my fill water has 300-500 ppb phosphates added by the municipal water district and I also get blown-in fertilized soil (fertilizer has phosphates and nitrates).

If you are using Trichlor tabs/pucks, keep in mind that for every 10 ppm FC added by Trichlor, it also increases CYA by 6 ppm. So if there is no water dilution, then even with a low 1 ppm FC per day chlorine usage the CYA will increase by over 100 ppm. So you are lucky you don't get algae more frequently. If you want to avoid algae growth, you need to raise your FC level as the CYA level climbs over time or you need to use a weekly algaecide such as PolyQuat 60 or need to use a phosphate remover -- both at extra cost. You can use The Pool Calculator to calculate dosages and can learn more at the Pool School.

I'm not sure where you would buy larger boxes of Baking Soda.

Richard