Jandy SWCG's "optimal" water conditions: why raise CYA?

[BigTallGuy]

Have you received the Taylor kit yet? I think you will find there is a BIG difference between 'barely adequate' and a good test kit. If I remember right your old test kit was OTO and not DPD. There is a reason that the Taylor kit is recommended, otherwise we would probably recommend getting a cheap '5-way' kit from Ace Hardware and adding a CYA test to it. The end result is so different it is a case of apples and oranges!

Not yet. I am expecting it this week. I am looking forward to working with this kit when it arrives.

Yes, barely adequate vs. good, I'm sure is miles apart. But for the record, since May, 2010, when I converted to Salt along with a new liner and fresh water, My pool has been sparkling clean, without a single algae bloom or "green" day, and no burning eyes (thanks to many people on this Forum) I only have had to add bleach one time. All with my old test kit and a few tests at the pool store. So justifying the $57 for a Taylor kit was a little rough. My last bout with the CYA levels (different Thread) was the last straw.

The residual CYA in the liner, plumbing etc. was suggested before and is the only thing that makes sense, as it would be chemically impossible to repeat the readings with 4 Lbs. of CYA. I didn't know until now if this was a real possibility or a theory. Thanks for clearing that up.

[PoolDoc]

I can't see any way you could stow 4# of dissolved CYA in the liner and pipes. Not sure who suggested that, but unless it was Chem_Geek, I'd forget about it. If it WAS Chem_Geek, I've got a bunch of questions for him.

Ben

[chem geek]

BigTallDumbGuy was referring to waterbear's post where he wrote "When CYA levels are very hiigh for an extended period of time CYA tends to deposit in the plumbimg and pool surfaces and when you refill it residdolves and brings the level higher than you expect." I have heard that before in the context of there being a small amount of residual CYA reading in spite of pools being drained. However, 4 pounds of CYA in 11,000 gallons is 44 ppm and that's much higher than the kind of residual that can be left over. Since a proper test kit was never used in the pool being described that had CYA in it, I don't think it's worth spending any time trying to figure it out.

[BigTallGuy]

I agree Chemgeek, it is not worth trying to figure out. As I stated, that pool and its issues are long gone. However, there are 3 facts to consider.

1, Multiple vanishing black dot tests were performed at 3 different pool stores, and I'm sorry but I can't believe ALL of the tests were faulty tests. In all total, at least 6 different test were performed (2 per store). I asked each of the people performing the tests to be very careful with their testing. My CYA was over 100, way over.

2, High CYA readings (over 100) are reportedly difficult to read unless you do a little fancy dilution with distilled water, which none of the pool stores did.

3, I bought a 6 Lb. bottle and took the remaining unused CYA back to the pool store and had it weighed. with the bottle, there was 2.1 Lbs of unused CYA left over out of the original 6 Lbs. So I can say it with a pretty high degree of accuracy that 4 Lbs. was all I put in.

[waterbear]

1, Multiple vanishing black dot tests were performed at 3 different pool stores, and I'm sorry but I can't believe ALL of the tests were faulty tests. In all total, at least 6 different test were performed (2 per store). I asked each of the people performing the tests to be very careful with their testing. My CYA was over 100, way over.

2, High CYA readings (over 100) are reportedly difficult to read unless you do a little fancy dilution with distilled water, which none of the pool stores did.

.

And there you have it. It is IMPOSSIBLE to know how much over 100 it is without diluting and with dilution you lose precision. The CYA level might have been MUCH higher than thought. Many people, including pool store employees do not understand what precision means in water testing. Ben used to have a very good explanation page on PoolSolutions but it does not seem to be there anymore.