High CYA

[starswimmer]

[Split by moderator from HERE to avoid hijacking, jblizzle]

Same problem here with high CYA that I just discovered with my new K-2006 kit I got last week. And even though I've been lurking around here for four years, the relationship between the CYA and FC totally escaped me because I was told that CYA was not an issue for my indoor pool. (Yup, pool store again.) So now I'll be shocking with bleach and replacing the water for the next week to get rid of it. I have a small utility pump that will do the job. I haven't had any problems with cloudy water but I guess I've been lucky. Indoors and light bather load probably helped.

Why don't they make non-stabilized chlorine tablets btw? You guys provide a great service here. Thank you.
Ed

 

[duraleigh]

Re: CYA > 100, issue with FC in pool

Welcome to the forum. :lol:

Why don't they make non-stabilized chlorine tablets btw?

They guy who discovers how to do that will be a billionaire, for sure. Can't remember the exact science but it just can't be done........yet. :idea:

 

[starswimmer]

Re: CYA > 100, issue with FC in pool

I've begun replacing the pool water today. I hit on the idea of using the heated pool water to expedite the operation. I'm drawing warmer water from the shallow end and replacing it at the deep end with colder fresh water. The pool circulation pump is off. I figure the cold replacement water should settle to the bottom of the deep end (6') and force the warmer water to the surface and shallow end where it is being drawn off by the utility pump. This should be quicker than partially draining, refilling, partially draining, refilling, etc. I'll check the CYA tonight and see how well it's working.

The outgoing water temperature is about 83 deg. F. and the replacement water is around 55 deg. F. so there is a significant differential that should speed the process along. Rather than just let the cold water run into the pool water at the surface, I should probably run the hose down to the bottom so it will have less chance to mix with the warmer water. I'll go do that now.

 

[rkroner]

Re: CYA > 100, issue with FC in pool

I had to slog through my first year of BBB (about three years ago) with a puck-induced crazy high level of CYA and the resulting issues with FC level. One year of backwash and a winter, and i was on point!

Anyway, when i was away for a little over a week last summer, i did resort to pucks and due to the limited time, it didnt raise by CYA by much (about 10 PPM) but since i keep it pretty low (less than 40), it was back on point after a few weeks of normal backwashing.

 

[starswimmer]

Re: CYA > 100, issue with FC in pool

My CYA is off the K-2006 kit's scale, but estimated at between 150 and 200 ppm. I've been using 1-2 pucks a week for some time. They should put a warning label on the bucket. No backwash for the cartridges but I do replenish about 500 gallons or so 3-4 times a year. It dilutes but doesn't get rid of the contamination like backwashing does. Ten ppm in a week amounts to a lot of contamination over time.

 

[jblizzle]

Re: CYA > 100, issue with FC in pool

You can use 50% pool water and 50% tap water to start the CYA test ... then double the reading. If it is currently over 100ppm, it could be WAY over 100ppm.

Also replacing evaporated water does not lower the amount of CYA in the water, the CYA does not evaporate. It is only reduced when physically removed from the pool.

PS: please shorten your signature to 5 or less lines as stated in the forum rules ... Thanks

 

[starswimmer]

OK, got it. Thanks! It took me awhile to wrap my head around the part about adding water not lowering the CYA concentration. First the evaporation concentrates the CYA, raising the PPM number. Then adding fresh water returns the CYA level to where it was prior to the evaporation. It does dilute it but only back to where it was to begin with. I think we're on the same page now and of course the main point is, as you said, that dumping the CYA contaminated water overboard is the only way to get rid of the stuff without resorting to reverse osmosis. Thanks for the tip on the alternate way to test for it when it's high. Cheers, Ed

 

[starswimmer]

First look after partial replenishing the water is a CYA reading of about 180 using the 50/50 and doubling the reading technique. Very discouraging.

 

[duraleigh]

Very discouraging.

Yes, it is, but be encouraged that there are HUNDREDS and HUNDREDS of members on here who have gone through the same task and have gained the knowledge to manage a crystal clear pool all summer. You will too if you stick with it.

 

[jblizzle]

Mine was over 300ppm when I got rid of the pool service company. I replaced 90% of the water at once.

Getting the CYA down will make maintenance much easier.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[starswimmer]

I assume the high CYA was also contributing to my TA remaining high and my pH trending low in the past couple of years. Before that I was only having to raise the TA but pH stayed fairly stable. It was a mystery to me why this changed all of a sudden.

I think I'm down below 50 ppm on the CYA now. I'll check with the K-2006 kit later today. Since it's an indoor pool, is there a need for any CYA in my situation? I'd like to take it down to 10-20 ppm if possible and use the minimum amount of FC practical. (low bather load)

 

[Bama Rambler]

In an indoor pool you need about 20 ppm CYA. CYA helps moderate the FC so you're actually running a lower active amount of chlorine with CYA in the pool than you would be even at 1 ppm FC with zero CYA. If you'll read some of Richard's (Chem Geek) posts you'll see how that works.

 

[linen]

Bama beat me too it, but here are my 2 cents..

I assume the high CYA was also contributing to my TA remaining high and my pH trending low in the past couple of years.

High cya in and of itself does nothing to TA. However the Trichlor pucks you were using are acidic. The pucks would have constantly lowered your ph but at the same time they should have also caused your TA to slowly lower.

Before that I was only having to raise the TA but pH stayed fairly stable. It was a mystery to me why this changed all of a sudden.

What was you TA level then? How were you testing then? What is your current TA level? What is the TA of your fill water?

Since it's an indoor pool, is there a need for any CYA in my situation? I'd like to take it down to 10-20 ppm if possible and use the minimum amount of FC practical. (low bather load)

20 ppm should be fine (even 30 is fine), going to 10 ppm will only make it more difficult to test and maintain a consistent and appropriate FC level. There should be not measurabale difference in chlorine usage at 30 verses 10 ppm cya, unless unfiltered sunlight is able to hit the water, then it may actually use more FC at the lower cya.