Postby chem geek » Wed 18 Jul, 2007 10:31
I think the slight cloudiness is also due to the combination of pH, TA and CH since both TA and CH are high. I calculate a saturation index of +0.2 which isn't that high, but if the pH goes up at all then the water can get more cloudy, especially if Cal-Hypo is used as a chlorine source or for shocking (which I'm guessing it is since it add calcium and the CH is high -- unless the fill water was initially very high in CH). Are you also using Trichlor tablets? That would explain the high CYA levels -- I'm guessing you are using Trichlor for chlorine most of the time and using Cal-Hypo for shock, is that right?
I agree that the high CYA is harder to deal with since you need to keep the Free Chlorine level higher, but having it at 10 ppm (target 11.5, but absolute minimum of 7.5) should keep away algae unless you've already got a bloom developed that is consuming chlorine quickly.
As for the spray on the trees, if that was some sort of fertilizer or other chemical containing phosphates and maybe nitrates, then that is essentially algae food so could certainly accelerate algae growth. Though you could try and battle this with more shocking and higher FC maintenance, I agree with Backglass that a partial drain/refill to get your CYA level lower will make pool management easier since it will take less FC to do anything -- to shock or to maintain chlorine levels. This is because you most efficiently shock with a constant FC level of 40% of the CYA level. You then after all algae is gone, the FC holds overnight, and you measure no CC, you target an FC of 11.5% of the CYA level (with an absolute minimum of 7.5% of the CYA level).
After you've lowered your CYA via a partial drain/refill (about half of the pool water), your TA will probably be lower as well which is good and what you want since that will also help reduce cloudiness.
If you don't have one already, get yourself a good test kit, the Taylor K-2006 or the even better TF-100 from tftestkits(dot)com.
Richard
