Another CYA thread (but about Pucks)

[db5304]

Hey all,

I want to start by saying thanks for making my first year of pool ownership much easier. Thanks to the forum my my first year got much easier and I opened to a crystal clear pool (and a thicker wallet). With that said I replaced about 50% water due to draining low enough for winter, and then got hit with a lot of rain. I did a full suite of tests and CYA was below 20 so I couldn't even determine it. I since went through 3 pucks over a week period, and haven't retested myself yet. I went to the pool store to get some supplies and have them test it. There test results matched my pretty close (with the exception of my PH being wonky) so I trust it. My question is regarding bringing my stabilizer up. I'll post my numbers first:
FC 2.8
TC 2.8
CC 0
pH 7.7
Hardenss 140 (vinyl liner)
Alkalinity 76
CYA 15 (too low)

Now I haven't really been experiencing massive chlorine loss but my cover has been on, and it has not been sunny lately. I am going on vacation the week after next, and then I will be away for 3 weeks for work (leaving the untrained girlfriend to take care of the pool). I have lots of pucks I bought before finding the forum. Do I need to add stabilizer pronto, or can I count on pucks to bring it up slowly and keep my pool chlorinated? The pool store said I had to get my stabilizer up before anything, but I don't want it to get out of control trying to subsidize with pucks while i'm gone. I just read another post where the forum recommended the user bring up his CYA to 35, but would I be safe with this plan or should I do the same?

Second up, I tested my PH really low at like 7.2 (i hate visual tests), and added 2 boxes of borax, then got the pool store results and was a bit surprised. I bought their PH indicator thinking maybe mine was bad (only a year old test kit), got home and got almost clear with their indicator. Measured with mine again and got like 8.0. Did I have left over chemicals in my test tube? I always rinse it out, but why the crazy swing? After this I'm apt to believe the pool stores test results (they are at least the most honest of the stores I've been too and I do try to support them).

And thirdly (sorry for all the questions), they had granular chlorine, and said it does not add stabilizer. I thought I read this, but now cannot recall, is this actually true? Is liquid just typically cheaper, and why people buy that? I have a hard time sourcing liquid later in the season.

oh and any tips on footer valves? I bought a replacement for a leaky one last year and it was instantly leaky. The owner mentioned this is because of the DE filters and they all leak, so I just need to keep a plug in it. Any thoughts, tips, tricks on this or is he just right?

Thanks again for all the help.

 

[Jimrahbe]

db,

I see no reason you can't use your old pucks, until you get back from your trip..

One of the advantages (if you want to call it that) of being in the Frozen North is having to drain and refill water for the winter. This helps to keep the CYA level down.

Liquid stabilizer is almost always much more expensive and why most people use dry stabilizer.

I have no idea what a "footer" valve is???

Thanks for posting and good luck on your upcoming trip,

Jim R.

 

[Swampwoman]

Hi there. lets see if i can help.

re pucks for vaca -- For each 10 ppm of FC you add by puck, you'll be adding 6 ppm of cya. You're going to need to calculate whether or not 4 weeks of puck use will have you overshoot or not. Myself, I'd b inclined to raise cya now or else the sun will eat your FC. And teach GF to add liquid chlorine according to your normal use

2. There are TWO different types of red indicator for ph. I'm betting the one from the pool store was not the reagent meant for the FAS-dpd kit. The correct one is R004 not R0014. Check and see.

3. The only kind of powdered chlorine that does not add stabilizer is cal-hypo, which instead adds calcium. As LNG as you keep CH under 300, no harm in using cal-hypo to chlorinate now and then...eg maybe have girlfriend use while you're gone...just not an always" solution because it will cause your ch to get too high.

 

[Texas Splash]

About your three questions:
1. Our go-to answer about CYA is the minimum is 30. Are there exceptions? Sure. Like indoor pools, or if a pool is primarily covered in certain areas, they can get away with it. The challenge then becomes balancing FC so that's it's not too string but still sanitizes. Your other challenge is that the CYA test is not very accurate when below 30. Some might also depend on what your girlfriend can do for you while away (i.e. adding bleach with system running). If it were me, I would want the CYA at 30 just to be safe. Then she could add a little bleach every day or two for the FC, or you can still use some pucks. The CYA will increase a little in 3 weeks, but still be reasonable. You can see the effects of some pucks on the Poolmath calculator (Effects of Adding Chemicals).
2. As long as your R-0014 reagent is not crazy old or was stored around heat /sunlight, it should be fine. I would always trust my own testing over the store. I know we get curious and want to compare, but comparing with them just confuses the situation. Now if you had a neighbor with a TF-100 or Taylor K-2006 that would be great to compare.
3. Perhaps they're referring to Cal-Hypo. It will increase calcium but not stabilizer.

Hope that helps.

ha ha. How's that for a couple replies at the same time.

 

[zea3]

I'll try to answer all your questions as best I can.
1. CYA: Every puck you use will raise the CYA by 1.2ppm in your pool. I would go ahead and add enough CYA to reach 30ppm based on your current estimate of 15ppm. Then you can use pucks when you need without raising the CYA too high. Just be sure you keep track of how many you use. You will want to keep the CYA between 30 and 50 ppm. The best thing to do would be to teach your girlfriend how to test the pool so she can add what it needs while you are away. If no one is going to use the pool while you are gone, raise it to slam level before you leave and put the pucks in a floater. Run your pump on a timer.

2. Your pH indicator should be good if it was stored away from humidity and extreme temperatures. It should not be that different from the store indicator. Check the labels and make sure they are the same product. I would trust my own test kit numbers. Since you will be using pucks while you are away they will drop the pH a little bit while you are gone. pH of 7.2 is not too low, you just don't want to drop it below that number.

3. Granular chlorine comes in 3 types, dichlor which contains CYA, calcium hypochlorite which contains calcium, and lithium hypochloride which contains lithium. You won't come across the lithium hypochloride very often and its expensive. They may have been trying to sell you calcium hypochlorite. Look at the active ingredients on the label to see what it contains.

4. I'm not sure what you are referring to as a footer valve. Is it a check valve to prevent water from siphoning through the plumbing in reverse when the pump is off? Posting a picture of the problem area will help us troubleshoot your issue.

EDIT: Apparently I type slower than everyone else! But as you can see we are pretty consistent in our answers.

 

[db5304]

Wow great replies, Thanks everyone. I knew there was an issue with the powdered chlorine, it was the hypochloride they were selling. I will try to get some more granular cya to bring it up, I thought I had some but do not. I also did not realize the pucks were only 1.2ppm, I was thinking higher. The pool does get good sun and may be used. I also did not know there were 2 different PH indicator types. They do not sell the DPD kit, so I doubt it was the right kind (will check shortly).

The footer valve is the drain valve at the bottom of the Hayward DE filter.