CYA Cold climate question

[nhguy]

(Please pardon the newbie question - I read pool school and browsed for a few hours)

I just had a pool installed last October, filled with a water truck. We opened it for the season a few weeks ago (only because we were pouring the patio around it) - it's way to cold, rainy to swim in right now (looks pretty clear though!). It came equipped with a chlorinator that fits about 6 pucks in it.

My pool will only be open for about 5 months out of the year (due to weather). I understand that the chlorine pucks will constantly introduce CYA. We get feet of snow in the winter, and inches of rain throughout the spring/summer. I wanted to see if any other cold weather pool people out there that actually test for CYA and use/don't use the pucks - I'd be interested in your experiences. I'm also very interested in any opinions from this knowledgeable forum.

I'm trying to figure out if the pucks may be a good thing (for me) to try to level out my CYA due to how long my pool is closed and the amount of water nature puts into it.

I know I need to test, test, test (and I plan to as soon as I get my kit that I just ordered), but I'm wondering if there's any conventional wisdom about CYA and cooler climate pools.

Thanks!

 

[JasonLion]

Welcome to TFP!

If you have a short swim season and you backwash a fair bit and nothing really goes wrong it is possible to get through an entire season using trichlor tablets. But to be able to go another year after that depends on either the CYA vanishing over the winter, which happens sometimes, but is hardly dependable, or massive amounts of water replacement.

 

[Freelancer]

The swimming season that you describe is pretty much what I get here.

The method I use is during the winter I use floaters and pucks.. Chlorine demand is very low and CYA is very slow to build up due to the small amount required. I try to get my CYA up to 50-60 PPM for the start of the season. I then switch to bleach only for the swim season taking CYA readings every 2 weeks. Usually by the end of the season the CYA levels are down around the 30 PPM mark and I then switch to pucks again when the season ends.. Recently though I've had to add CYA to a number of pools because despite the use of pucks during the closed season it did not put enough CYA into the water. I've used this method for a number of years and found it works great.

 

[nhguy]

I just became a supporter of this forum (coughed up $30) as I've browsed for hours and feel like I've have gained invaluable knowledge. I encourage anyone who feels like they've gotten good advice to do the same (keep it going, you cannot buy this type of advice).

I got my test kit (K-2006) last Friday and things seemed OK, except PH was a little low (7.2) and my CYA was reading 0 (not surprising, new pool water).
Initial Readings:
FC 2.5
CC 0
PH 7.2
TA 110-120
CYA 0 (or not on the scale yet)

Taking the Pool Calculator's advice, after a visit to Walmart and $3 worth of Borax - I've raised my PH to 7.6. My FC is down to 2.0, so I think I'll dump in some 12% HC to bring it up to about 4% for now.

The water's looking great, and the kids aren't swimming yet (water temp 62 and high of 60 today), but I'm just trying to get the hang of all of this. My plan is to work through the Tricholr tabs that I already have in my possession to bring up the CYA (won't really get into swimming season for a couple of weeks). I have a 40 lb bag of soda ash that I have no use for now (I have arsenic in the well water, used to use it to regenerate media for my old filter system - I have a new one now) - sounds like it'd be perfect to bring up my TA and PH moving forward until I bring up my CYA with the pucks. Then maybe I'll get the courage to be a true BBB'er

Any opinions (good/bad) on my plan would be much appreciated!

 

[JasonLion]

That sounds like a good plan.

 

[alben]

Do you suppose it is these cold climates that cause the CYA to go to 0 over the winter? I closed the pool last fall with a very high CYA of 90. Last week when I opened the pool, the CYA was 0. So I used enough dichlor last week when opening my pool to bring CYA up to 35. The rest of my chlorine has been 12.5% bleach.

In case you are wondering, the CYA was so high last year, because I was not aware of the BBB method, and had been using dichlor most of last year's season, which caused CYA to go up to 90. I had a feeling it would go down over the winter, and it did, down to 0.

I live in Minnesota. Any idea what the ideal CYA would be for this climate, using strictly the BBB method (no SWG) and vinyl lining?

 

[JasonLion]

CYA around 30 to 50 should be just fine. When it is hot and sunny you sometimes have to take CYA higher than that, but that obviously doesn't apply to you

 

[chem geek]

Do you suppose it is these cold climates that cause the CYA to go to 0 over the winter?

We don't always know why it sometimes goes away, especially when one opens to no CYA without high chlorine demand. It's unlikely it's the cold, but we really don't know. When you opened the pool did it have cloudiness or algae? I also assume that you warmed the water sample up to room temperature before doing the CYA test; otherwise, it can be slow to react with the test reagent and measure artificially low.

 

[nhguy]

I've read some of the very informative posts from chemgeek and tried to figure out how much CYA the trichlor pucks in my possession will add to my pool. I've tried using some of his numbers with the pool calculator, but I'm not having much luck coming to a coherent conclusion. Is there a simple formula of how much CYA will by added by 18 lbs. of Trichlor pucks to 24000 of water?

Thanks!
FC 2.5
CC 0
PH 7.7
TA 110-120
CYA 0 (or not on the scale yet - can't get the Dang dot to disappear!)

 

[chem geek]

Use The Pool Calculator and first enter in the Size of 24000 gallons. Then scroll down to the bottom under "Effects of adding chemicals" and set it to "trichlor" and then enter in 18*16 = 288 ounces to see that this raises the FC by 99 ppm (of course, not all at once, so cumulatively added and consumed) and the CYA by 60 ppm. Note that Trichlor dissolves slowly so the rise in CYA will be slow. If your chlorine demand is 2 ppm FC per day, then you will add 2*30*0.61 = 36-37 ppm CYA per month.