North Texas CYA Level

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Bevostein

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LifeTime Supporter
Dec 5, 2012
37
Frisco, TX
New pool owner here...(2 months old, filled June 28th)....I am curious what CYA level folks in North Texas are using.

MY CYA is 40. Pool looks great but I am putting in 70-90 ozs of 8.25% bleach each day. I am losing about 2 - 3.0 ppm per day with zero bather load since Monday. I did an OCLT earlier this week and showed a 1.0 drop over night and CC is always .5 or less so I don't think I have any major organics. I am going to do another OCLT tonight to make sure it doesn't need slamming. Assuming I pass the OCLT again, I am wondering if I need to bump up my CYA to bring down my daily FC loss. Seem like a lot to be dumping in daily. My pool starts getting sun at 9am and by 10 its in full sun. Starts getting shade at about 6pm and gradually gets more shade until sundown. Thoughts?

Latest test from last night before I added bleach and MA

CYA - 40
FC - 4.5
CC - 0.5
pH - 7.6
TA - 80
CH - 270
 
Yeah, I would bump your CYA to 50 ppm. Your FC loss is not atypical so you might only save 1 ppm daily FC.

You'll have to balance that savings with the cost of the additional CYA and see if it makes sense as we approach the end of the swim season.
 
Thanks - Sounds like I will slowly move it to 50. I had thought 40 would be right with my theory being that 40 gave me room to use pucks when we go out of town for an extended time. I would rather try 50, use a little less daily bleach and hopefully have enough CYA loss through splashout and rain dilution that I can occasionally use pucks when out of town. Either that or add a Liquidator or peristaltic pump at some point.
 
I guess I'm the exception to the rule...I keep my CYA between 30 and 40 ppm. My pool is in full sun for much of the day. No shade trees in back yard. One thing I'm diligent about is keeping the skimmers and pump filter basket clean of all debris. Your pool surface can look clean, but if there is accumulating debris in the skimmer and pump filter baskets, it can result in small parasitic FC consumption. My average daily FC loss at this time of year is around 2 ppm. Sometimes it spikes up to 2.5 ppm while on more overcast days it is less than 2 ppm. Yesterday, I lost just 0.5 ppm :!: but it was partly to mostly cloudy with air temps in the upper 90's and water temps between 86-87°F.

As we often say, every pool is different. I would suggest increasing your CYA gradually until you find the sweet spot. It's like adding salt to a recipe...easy to add a little more, but more difficult to deal with if too much is added.

Bevostein said:
I did an OCLT earlier this week and showed a 1.0 drop over night and CC is always .5 or less so I don't think I have any major organics.
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Might want to pull your light fixture and check the fixture and area behind it and clean as necessary. Here's an example: http://www.troublefreepool.com/think-i-may-have-found-my-fc-demand-issue-t65957.html. Same goes for any ladders or underneath removable steps if your pool has either. I'm seeing more posts about higher than normal FC consumption resulting from stubborn organics hiding behind light fixtures, around ladders, and underneath removable steps even though pool water looks clear. These are typical areas of low circulation.
 
Thanks for all the responses. I passed the OCLT last night with no loss and only the faintest trace pink when doing the CC. I feel very confident I don't have any organics. At least until my kids got in it this morning after football practice.

Bo - We are close to each other, our pools are about the same size, CYA level is the same and exposure to sun sounds similar. I am also seeing 2-3ppm loss each day which is pretty consistent with yours. That helps me feel better about how I am doing with mine.

I think at this point I am going to bump up the CYA just a tad and see if that will drop my daily loss at bit. We have only had the pool 7 weeks at this point so between it still curing and me coming up to speed on caring for it, I feel good about where I am at. At this point I am more interested in getting it really dialed in and then adding borates at some point.
 
N in Houston and my CYA is at 50. I'm in full sun with a high bather load...3 kids and whatever friends come over. Yesterday morning m TC was 7.0. We swam intermittently yesterday then had a night swimming party with 6 adults in the hot tub and 8 kids in the pool. This morning my TC was 1.0.

I'm getting sick of the huge swings in chlorine so for my pool and lifestyle I'm using pucks for a few more weeks to get to 60 or 70. We get a lot of splash out and evaporation so I add water at least once per week, in turn lowering CYA. I think higher CYA in my situation is needed. I'm not skurred! Okay, I kind of am but I think it's best for me. ;)
 
In your 17,000 gallon pool, every person-hour of use is roughly 0.06 ppm FC usage unless someone urinates which would be more (each cup of urine would be around 0.4 ppm FC extra demand). If the kids were in for one hour, then 11 person-hours would be 0.66 ppm FC chlorine demand. Most of your chlorine loss is probably from sunlight and that is easily verified by comparing the no bather-load chlorine loss during the day and comparing that to overnight which should be negligible (if it's not, then you've got some other source of chlorine demand). At 50 ppm CYA, a more usual 24-hour no bather-load loss would be around 40% so from 7 ppm to 4.2 so you've definitely got more than that.
 

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I'd say my 3 kids swam two hours during the day. Then 11 people swam at night for about 3 hours. Some kids are little, so there was definitely pee in the pool. ;)

Do you think 7ppm in 24 hours with those details sound plausible or would you still suspect something funky growing?
 
So that's 39 person-hours which would be around 2.3 ppm FC chlorine usage. So going from 7 to 4.2 from sunlight and normal decline plus another 2.3 from bather-load would put you at 1.9 ppm FC which is higher than you saw, but not wholly out of line, especially if anyone urinated. Again, you can tell how much you are losing from sunlight by measuring during a 24-hour period when the pool is not used, but the day is still sunny.
 
chem geek said:
In your 17,000 gallon pool, every person-hour of use is roughly 0.06 ppm FC usage unless someone urinates which would be more (each cup of urine would be around 0.4 ppm FC extra demand). If the kids were in for one hour, then 11 person-hours would be 0.66 ppm FC chlorine demand. Most of your chlorine loss is probably from sunlight and that is easily verified by comparing the no bather-load chlorine loss during the day and comparing that to overnight which should be negligible (if it's not, then you've got some other source of chlorine demand). At 50 ppm CYA, a more usual 24-hour no bather-load loss would be around 40% so from 7 ppm to 4.2 so you've definitely got more than that.
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Wow that's some good info. Thanks. I've wondered how much I need to bump up chlorine leading into or following a swim party. That helps. Thanks. You are earning your username with that post!
 
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