My parents have religiously used tabs through the years. I warned them about overstabilizing, but imagine my shock when CYA tested very low (20). Yes, there is significant dilution because of backwashing (sand filter) and fill-ups (evaporation), but if I was going to place a bet on their CYA level, I would have guessed closer to 100.
So, now I'm trying to raise CYA (carefully so as to not overdo it). Naturally, I would think the pucks would do it - but it's been 2 weeks and it's still in that 20 range. Is there anything that would make 3" trichlor tabs lose their effectiveness as CYA source? The only other possibility is that I'm adding it so slowly that it's really not registering. They do have about ½ gallon of liquid conditioner (>1 year old) that should in theory raise CYA by 15 ppm.
Funny thing is that their HOCl usage is about the same as mine: both of us are using 2½ gallons/week - me with 15K gallons/70 CYA/50 borates and them with 14K gallons and the aforementioned 20 CYA (I just added borates, so I'm discounting that). We're both in similar sun situtations (high - though mine may get an extra hour than they do due to shading). I would have thought they'd consume more.
Thoughts?
So, now I'm trying to raise CYA (carefully so as to not overdo it). Naturally, I would think the pucks would do it - but it's been 2 weeks and it's still in that 20 range. Is there anything that would make 3" trichlor tabs lose their effectiveness as CYA source? The only other possibility is that I'm adding it so slowly that it's really not registering. They do have about ½ gallon of liquid conditioner (>1 year old) that should in theory raise CYA by 15 ppm.
Funny thing is that their HOCl usage is about the same as mine: both of us are using 2½ gallons/week - me with 15K gallons/70 CYA/50 borates and them with 14K gallons and the aforementioned 20 CYA (I just added borates, so I'm discounting that). We're both in similar sun situtations (high - though mine may get an extra hour than they do due to shading). I would have thought they'd consume more.
Thoughts?