CYA 230, replaced 1/2 of water...now 217???

Hi - the reason I detected the high CYA was that I was getting a rash from swimming...and so began the research and I was suspecting pseudomonas.

I had my water tested and was told that the chlorine isn't doing anything at all being that the CYA is too high. This might explain why after shocking a month ago it took 10 days for the chlorine level to drop down to 2ppm. I should mention that my water has no odors, no cloudiness, no green tints or algae - it's crystal clear!!

Background (before replacing water)
- 30000 gallon plaster pool
- Cl = 1.3ppm
- PH = 7.6
- Alkalinity = 160
- CH = 530
- CYA = 230!!!

I then drained almost half the pool, so I'd say I replaced 12000 gallons of water. Then I shocked the pool - and took my water back to the store for testing.

- Cl = 10ppm
- PH = 7.7
- Alkalinity = 100
- CYA = 217????

What the **** is going on here?
For one I don't understand how the CYA could only drop 13ppm after replacing 40% of the water. For two - can someone please tell me what to do from here? The guy at the pool store said "try replacing the sand in the filter". I don't know if he was just grasping at any solution....

Thank you,
Matz

candy - how are you determining the CYA values? Are you relying on the pool store or testing yourself using a reliable test kit? I never could get consistent results from the pool store.

It would be difficult to distinguish 200 from 400 using the Taylor test. I bet your CYA was even higher than 230 before the water replacement.

I would get a good test kit (Ben's or the Taylor) and test yourself to see where you really are now. Be warned though, the CYA test is a bit subjective. There are some good posts on this forum on how to conduct the test for reliable results. Good luck.

BTW - the guy at the poolstore who said to change your sand is a knucklehead.

Thanks for the reply rbonin.

I have a testkit from Leslie's. It looks identical to the Taylor Troubleshoot Kit, except mine has the ability to test CYA and Calcium Hardness as well. I'm basing my 230 and 217 figures from Paddock Pool's testing though, where they use some test strip under ultra violet light. So those numbers are the before and after at the same place.

However, I will say that I tested myself when the number was 230 and it seemed to end up about the same, but when I retested after replacing water, mine came close to 140 or so...which is a guess because the test tube only goes to 100. Maybe mine is more accurate...? I guess I trust the pool store more than my own newbie numbers.

Let's assume I'm right and the number is 140, the store tells me that 30-200 is the limit...but online everyone says 30-50. Which is correct?

Also, do you think that it's likely that I have pseudmonas in the pool when it's clear as crystal?

Thanks!
PS. Sounds like I don't have to add the sand change weekend project to my list

I have seen some information that implies that CYA testing is not accurate over 100ppm, and that it may be much higher than the indicated value.

Quote:

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Originally Posted by Candyass

Let's assume I'm right and the number is 140, the store tells me that 30-200 is the limit...but online everyone says 30-50. Which is correct?

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My 'official' printout from the pool store (Alex - BioGuard) says that 30-200ppm for CYA is ideal. Online I've read that over 50ppm CYA seriously compromises chlorine.

:confused:

TW

The catch with stabilizer is that at higher concentrations, it renders chlorine less effective at sanitizing. Here is a chart that is popular on this site:

Stabilizer . . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
=> 0 ppm ... . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
=> 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
=> 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
=> 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
=> 100 - 200 ppm . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

You can see that at your current CYA concentration, you will have to maintain at least 8ppm free chlorine for effective sanitizing. I think most on this site would recommend you shoot for 30-50 ppm CYA, but I guess it depends on how much sun your pool gets. I keep mine at 40ppm and mine is in direct sun all day.

~Rick~

rbonin - I thought it was "dangerous to your health" to swim even at 5ppm FC levels? It says on shock packaging to not swim until FC levels have dropped to at least 5ppm. Which is correct? Is it safe to swim in 8ppm?

Sorry for all the questions - I'm new to this.

Thanks,
matz

What did you use to shock the pool after refilling it?

Donna's Poolboy - I used Leslie's Chlor Brite Sanitizer. Granular shock which I dissolved in a bucket before pouring into the pool.

Picture here: http://www.lesliespool.com/shopping/...rd=chlor+brite

Thanks,
Matz

The Chlor Brite shock you aded to the pool contains CYA adding more to your headache. I think everyone hear would tell you to stick to just bleach.