Using tablets as a supplement for granular?

Hi. I have a 40k gallon, in-ground pool with vinyl siding and a DE filter. I usually add 6 to 12 grams of granular chlorine daily, depending on temperature, recent or upcoming rain, etc. For awhile I have been under the impression that chlorine tablets where simply an alternative to granular chlorine, but I did not like the idea of using them because I felt I would have less control over the chlorine levels than with granular.

Recently I was told that the correct use of tablets is to keep chlorine levels steady over the course of the day, and to act as a 'supplement' to granular so less can be used.

I was hoping someone here could clarify the matter for me, and perhaps give me some tips on how often I should be adding granular to a pool of this size were I to go with the tablet-supplement course of action?

Thanks!

Chlorine is chlorine once it is in the pool. The tabs have CYA in them and are fine to use if your CYA level is not too high. But make sure there is no copper in them You do not want copper in your pool. Some people use them when they go on vacation to maintain some chlorine in the water.

Granular is either cal-hypo or dichlor. If it is dichlor, it also adds CYA. If it is cal-hypo, it adds calcium

Another difference is that granular can be used to shock a pool whereas you cannot shock with tabs.

Do you have a K-2006 kit? If so, post a current set of readings.

I use Chlor-Brite granular, which is a dichlor. I only have the Taylor basic test kit for Chlorine and PH levels, which I keep within normal levels (7.5 for the Ph and about 2.0ppm for the chlorine). I have poor color vision that makes it difficult for me to accurately read the different color gradients on those tests though, which is part of what keeps me from buying one of the more complete test kits like the one you mentioned. Still, I have not had any trouble keeping the pool algae-free.

If you use trichlor and dichlor without periodically checking CYA levels, you may end up with algae because as CYA increases, so must chlorine. Take a look at the Best Guess Chlorine Chart in my signature below for more info about that.

Thanks, I probably should get a more comprehensive test kit like the one you mentioned. Better safe than sorry, after all.

But, with the tablets, is that the 'proper' way to use them, as a sort of supplement between less-frequent chlorinating?

Some people use them as their only source of chlorine until their CYA gets too high and then they switch. Some people only use them when they go on vacation. Some people use them along with other types of chlorine. There is no one "right" way to use them. Personally, I don't use them. I use only bleach and just add my CYA separately when I need to increase it.

I decided to go ahead and order the K-2006C testing kit so I can keep better track of my chemical levels. Since it won't be here for a few days, I got a pool store water test done. They say my calcium hardness is low at 100 ppm, total alkalinity is low at 60ppm, and that phosphates are high at 200ppm. CYA tested at the lower end of normal at 30 ppm.

They wanted me to buy a bunch of stuff but I wanted to come here and see what you guys have to say about where I should go from here. The pool is looking fine so there's no rush. Would it be better to just wait for the kit to arrive so I can take the measurements myself?

Thanks

You have a vinyl pool. No worries about low calcium. Pool stores are notorious for trying to selling people calcium when they don't need it.

Yes, just wait on your kit.

This is a good question and one ive been wondering about myself. I am strictly a granular user, hth from walmart. Iv'e noticed my ph starting to rise and was wondering if tabs could help me with that. i may try some.

Bosch, be sure you test your CYA first to make sure you have room for any increase since those trichlor tabs have CYA in them.