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

[waterbear]

So, Cya of 30 and FC-1.5, running a SWCG/DE Filter 12hours a day on 50% isn't necessary?
I should raise CYA to 60 and FC of 3 with less time on the cell?

I must say this is a great forum...

NO, you should raise it to 80 and maintain the FC at 4 ppm. The difference between 60 ppm and 80 ppm has been determined to be significant and directly translates into better pH stability in a salt pool.

[BigTallGuy]

Thanks Evan. I appreciate your reply. I am embarrased, and publically admit you were right about the CYA. I must have read the Pool Info, Not the SWCG info. Please accept my apologies.

In my case a few years ago, the Problem with the CYA was on a Fresh fill. I drained my pool to less than 1 inch of water and refilled. After adding the CYA, and discovered the "high CYA Problem", I had the water tested at three different pool stores (before I ever heard of this Forum) and not one could find anything wrong with my pool chemistry. The unanimous consensus was high CYA as the cause of the eye irritation. I cannot explain how 4 Lbs. of CYA took me to readings in excess of 110 PPM in approximately 11,000 gallons of water, nor can I explain why draining 2/3 of the pool water (the following year) and refilling with fresh water took me to 100 ppm. But that pool and all its water and problems are long gone, so it will remain a mystery.

Yes I am a slow learner, I don't just go out and buy or do everything everyone tells me to until I investigate it. After all when your own children and grandchildren tell you that their eyes burn in your pool, I will err on the the side of caution. As far as the test kit is concerned, my old one was barely adequate, but wouldn't test CYA, so yes, I ordered the Taylor.

Thanks again Evan, and Peace.

Rick.

[waterbear]

Thanks Evan. I appreciate your reply. I am embarrased, and publically admit you were right about the CYA. I must have read the Pool Info, Not the SWCG info. Please accept my apologies.

In my case a few years ago, the Problem with the CYA was on a Fresh fill. I drained my pool to less than 1 inch of water and refilled. After adding the CYA, and discovered the "high CYA Problem", I had the water tested at three different pool stores (before I ever heard of this Forum) and not one could find anything wrong with my pool chemistry. The unanimous consensus was high CYA as the cause of the eye irritation. I cannot explain how 4 Lbs. of CYA took me to readings in excess of 110 PPM in approximately 11,000 gallons of water, nor can I explain why draining 2/3 of the pool water (the following year) and refilling with fresh water took me to 100 ppm. But that pool and all its water and problems are long gone, so it will remain a mystery.
No mystery at all. I have seen it many times. 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. As far as the pool store folk not knowing why the water was making burning eyes...well, since I used to work in a pool store I don't have a lot of respect for a lot of people that work in them, 'nuff said?

Yes I am a slow learner, I don't just go out and buy or do everything everyone tells me to until I investigate it. After all when your own children and grandchildren tell you that their eyes burn in your pool, I will err on the the side of caution.
But how do you know which way to err? Less is not always best (as the best guess chart shows with chlorine levels!)
Hypothetical point, If there were burning eyes and the pool store said that everything was fine (because their testing method bleached out at high chlorine levels and could not detect the combined chlorine in the water--actually, I have seen this happen--and someone else said to add more chloirne to get rid of the burning eyes but your chlorine was already high (and your CYA was high). would you give it a try to see if it worked? I believe you know enough about pool chemistry now to know it would!

As far as the test kit is concerned, my old one was barely adequate, but wouldn't test CYA, so yes, I ordered the Taylor.

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!

[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.

[BigTallGuy]

Thanks to all that responded. Famousdavis, I sincerely apologise for trashing your thread.