Latest results. CYA dropped.

[pb4uswim]

My latest numbers:

FC 15
PH 7.8
CYA 30
TA 60
CH 150
Salt 2600
Temp 71
CSI -0.38

We had about 6 to 7 inches of rain the past couple days and I’ve had to pump that out to get back to a proper level. Could that account for such a large drop in CYA? My one concern is that I just got new reagent and I’m a little concerned that either the old or new reagent might be bad (unlikely). Just seems like a very large drop for even that much rain/pumping.

My next question is, does it matter this close to closing? Does stabilizer do anything during the winter? I wouldn’t care but I’m going to have to drain my pool in the spring (crack in the fiberglass) so I don’t really want to spend extra to balance the pool before closing. I’m fine with adding chlorine and preventing algae, but it seems doing the minimum is called for in this case.

Thanks.

 

[Newdude]

Just seems like a very large drop for even that much rain/pumping

It’s an exact %. To lose half you need to drain half. And so on. So it’s unlikely from 6-7 inches of rain. Man tho. The pool Gods sure have picked on you this season.

My next question is, does it matter this close to closing

IMHO, no. Keep the FC up and you’re gonna start over next year.

but it seems doing the minimum is called for in this case.

Also IMHO you have done more than most would have. They would have limped along months ago. So there is that. Have a celebratory beverage.

 

[pb4uswim]

Man tho. The pool Gods sure have picked on you this season.

In all seriousness, I'm so happy with the pool, and thankful for the life I’m living in retirement, none of this bothers me. I kind of enjoy the chemistry nature of keeping the pool clean and challenges just make it that much more interesting. Of course, having a great resource like this site is one heck of a blessing. The internet is so cool when it facilitates learning and the flow of information like this. Especially now that I’m retired and there’s no water cooler to get input from.

I know this is taboo, but I have to get some chlorine so I’ll take a water sample to the pool store. Just for kicks, I always do that anytime I buy something from them. I know it goes against conventional wisdom, but their numbers do actually track very closely with mine. It will be interesting to see what their CYA number is.

Re: CYA: The last time I bought reagent, I bought the kit that uses a smaller tube and less reagent. Still, as far as I can tell, it’s a 50/50 mixture of reagent and pool water but just throwing it out there in case there’s some reason that would get things screwed up. This time I just bought the 8oz refill and today was the first time I used it. I did use the lesser amount and the smaller tube but I don’t think that could have messed with my readings. I did the test a couple times and there was no doubt that I could see the dot until I got between 40 and 30.

 

[Newdude]

I know this is taboo, but I have to get some chlorine so I’ll take a water sample to the pool store. Just for kicks, I always do that anytime I buy something from them. I know it goes against conventional wisdom, but their numbers do actually track very closely with mine. It will be interesting to see what their CYA number is.

You *can* do whatever you like. Ever. Wanna bring it in just for kicks ? Enjoy. We hardcore recommend against putting any faith in it, and hardcore HARDCORE suggest ignoring whatever they say about it, regardless of the results. . Past practice kinda lining up with you is great, but there are no promises for next time.

Still, as far as I can tell, it’s a 50/50 mixture of reagent and pool water but just throwing it out there in case there’s some reason that would get things screwed up

That’s exactly it. Different tubes and mixers with the same 50/50 mix. The fat CYA viewing tube with the 15ML sample squirter are irrelevant. But. Some folks see better with the skinny sight tube VS the fat one, or vice versa. It’s SO Gol Darn subjective….. whatever helps them mentally…….. who’s to say it doesn’t help them ? Lol.

 

[pb4uswim]

My local store is an independent shop which I think helps. Regardless, I do absolutely agree that I don’t listen to anything they say about the results. I respect the fact that one cannot serve two masters. That would drive me crazy. I’m committed to the TFP process. No worries there.

However, if their CYA number comes out higher and closer to what it was before this reagent, I may buy some of their reagent and see if I get different results. I know TF test kits does a great job, but there’s always a possibility that a batch is bad. The “chemist” is curious now. Better would be if I can find a local person that has a pool and some reagent. Maybe a post on Nextdoor is in order.

 

[Newdude]

However, if their CYA number comes out higher and closer to what it was before this reagent, I may buy some of their reagent and see if I get different results. I know TF test kits does a great job, but there’s always a possibility that a batch is bad

Always. And as unlikely as it is, it’s likely-er than the CYA dropping that much on it own.

I’m committed to the TFP process. No worries there.

Oh yeah !!! Wasn’t worried about you At. All. Just put that out for future readers who may be new and whatnot.

 

[pb4uswim]

Went to the pool store to pick up some antifreeze and had them check my CYA. They tested it to be 17. I have no idea what could be happening but I only had about 6 inches of rain, which I pumped out, and my CYA was over 60 before that. I did have some evaporation and put in a couple inches a week or do ago so let’s say 8 to 10 inches of new water. Doesn’t make sense.
Oh well, swimming today and tomorrow and then going to let it cool off and close it. Thanks for the input.

 

[mknauss]

Your Poolmath logs show you last tested CYA at 60 two months ago. So a drop to 30 now would not wholly unusual with some rain overflow and natural degradation of the CYA.

 

[pb4uswim]

Your Poolmath logs show you last tested CYA at 60 two months ago. So a drop to 30 now would not wholly unusual with some rain overflow and natural degradation of the CYA.

I’ll have to take your word/experience for it. Thanks for your input.

 

[wireform]

With CYA evaporation doesn't come into play it's either splash out or drain off and time that will get you a lower CYA.

 

[pb4uswim]

With CYA evaporation doesn't come into play it's either splash out or drain off and time that will get you a lower CYA.

That’s what everyone says, but it’s hard to explain why mine dropped so much so soon. Didn’t have hardly any splash out and the rain and subsequent draining doesn’t make sense to account for the drop. Time? I don’t know, does it deteriorate with time? Doesn’t seem like that would account for it either. As mknauss points out, my last log was a couple months ago. However, during those two months, I added stabilizer and was up to about 70 (added two pounds). This drop was precipitous.

 

[mknauss]

CYA does degrade with time. 10-15% per month during summer. Also test error is at best +/-10 ppm.