Brown, dusty algae

[cynlys]

Have had pool for 16 years 16x32 inground, vinyl lined, sand filter, heater, in-line chlorinator. Three years ago began experiencing this brown, dusty "stuff" that I have vacumned to waste, shocked the devil out of and it re-appears constantly within 24 hours. Went away from Burn Out 35 to liquid chlorine last year with no improvement. When I sweep the pool, the "dust" explodes and the water remains crystal.

Had my water chemically analyzed this morning at pool supply store (Bioguard) and the results are below:

Saturation Index .2
TDS 900
CYA 46
Total Chlorine 1.3
Free Chlorine 1.1
pH 7.6
Total Alkalinity 192
Total Adj. Alkalinity 178
Total Hardness 178

Have decided to go to your BBB program and anxiously await your recommendations to solve the problem and would appreciate any help I could get on what constitutes a daily/weekly maintenance program using BBB

cynlys

[cynlys]

Thanks for help, I think

[chem geek]

If you have mustard/yellow algae, then with your 46 ppm CYA level it will take shocking with Free Chlorine at 25 ppm (after first lowering your pH to 7.2 using Muriatic Acid before you add the chlorine) and holding this chlorine level until there is no drop in FC overnight and/or a full week. See this thread for ideas on how to determine if this is really mustard/yellow algae or if it is pollen or dirt that is getting regularly blown in.

Richard