My 15.6k gallon pool uses 2-3 ppm FC daily this time of year. We are going to be away for several weeks so for the first time in my 3 seasons of pool ownership, I am going to have to bite the bullet and use tablets. We do have an in-line feeder for 3" tablets, but I've just never used it so I have some questions. Also, I have someone who can come by 1-2x a week to check things, but not more often than that, so sticking with straight LC isn't an option.
I am most concerned about run-away CYA levels while being gone for 4 weeks. My CYA is 50 now, but on the advice of this forum, I have raised it as high as 70 to help with the especially hot Texas summers and it has worked. So I feel like I have at least 20 ppm CYA headroom. But I also don't know how many tablets I will use per day or week when I'm gone. (I hope to experiment this week to find out, but time is short before departure.)
Looking at the "Effects of Adding" in the Pool Math app, it says 8 oz of trichlor (I am guessing this is the weight of one 3" tablet) will raise FC by 3.1 and CYA by 2.1 (yikes!). If I go through one tablet a day (is that crazy?---I don't know---I run my pump about 5 hours a day at 1400 rpm) to get my 3.1 ppm FC, then I'll raise CYA by about 2.1 x 28 = 58.8 in 28 days! Am I interpreting this correctly?
If so, I obviously need an alternate plan. I thought about alternating trichlor tabs with cal hypo tabs (once the feeder is completely empty of course) to try to balance chlorination needs with runaway CYA, but cal hypo tabs are actually hard to find (especially in time before I leave).
Any advice, suggestions, or corrections to the above are welcome! Thanks!
PS Needless to say, this only makes me want a SWG even more!!!