Hi,
Broad context: I've recently switched to using liquid bleach from the Frog Pool Tender system. The Pool Tender is still installed, but I haven't had chlorine cartridges or tablets (via skimmer or modified Pool Tender cartridge) in the system for several day now (not quite a week, I think). The pool tender DOES still have the 'mineral pack' in place. I don't know exactly what it's adding to my water, and I guess for that reason I should probably remove it. I doubt any of this contributes to my question, but, I mention it just in case someone knows that it does.
Immediate context: As above, I've recently started using liquid bleach (10% is what I've found locally, for ~$6/gallon), and I'm trying to dial in my routine, and get a sense for how much I need to add daily. I have the TF-Pro test kit, and typically measure my FC and pH every morning. Because I have a hard time with the little OTO/pH test block (matching colors), I use the FAS-DPD test for FC, and an Apera PH60 to measure pH. I recently read here that it's better to add bleach in the evening than the morning if you're adding it manually, because the FC has all night to kill little buggies (at a higher ppm) before the sun starts to beat up the FC (lowering the ppm). This makes sense to me, so I decided to try it.
I'm trying to hit a target FC level of 7ppm when I add bleach.
Last night, I went to check the FC (being the first time I did it in the evening), and I don't know if it's because I was working in the dark, and couldn't really see what I was doing, but I was getting FC levels all over the place. My first reading was 3ppm, which was lower than I expected. I figured I'd see about 4.5 ppm. So I checked again, ... and again... and again. I did at least 4 checks (sorry, didn't record them), and saw a low of 3, and a high of 7. While getting these results I experimented with just how 'heaping' my scoop of R-871 was, as I'd read the detailed instructions indicating that too much ("within reason, " whatever that means) is fine, but too little is bad.
I cleaned everything up and went inside without adding any bleach.
This morning, I did it again, and got 3.5, 4, 4, and decided to go with the 4, and added the indicated 2qt 1cp (72oz) of bleach.
My question is, have others seen such wild fluctuations in their FAS-DPD testing results? Any ideas what would cause that? Bad reagent, maybe? (My kit is fairly new - I think I bought it in June).
Up until now, I've never bother repeating the tests like that - just do it one and trust it.
Thanks
Broad context: I've recently switched to using liquid bleach from the Frog Pool Tender system. The Pool Tender is still installed, but I haven't had chlorine cartridges or tablets (via skimmer or modified Pool Tender cartridge) in the system for several day now (not quite a week, I think). The pool tender DOES still have the 'mineral pack' in place. I don't know exactly what it's adding to my water, and I guess for that reason I should probably remove it. I doubt any of this contributes to my question, but, I mention it just in case someone knows that it does.
Immediate context: As above, I've recently started using liquid bleach (10% is what I've found locally, for ~$6/gallon), and I'm trying to dial in my routine, and get a sense for how much I need to add daily. I have the TF-Pro test kit, and typically measure my FC and pH every morning. Because I have a hard time with the little OTO/pH test block (matching colors), I use the FAS-DPD test for FC, and an Apera PH60 to measure pH. I recently read here that it's better to add bleach in the evening than the morning if you're adding it manually, because the FC has all night to kill little buggies (at a higher ppm) before the sun starts to beat up the FC (lowering the ppm). This makes sense to me, so I decided to try it.
I'm trying to hit a target FC level of 7ppm when I add bleach.
Last night, I went to check the FC (being the first time I did it in the evening), and I don't know if it's because I was working in the dark, and couldn't really see what I was doing, but I was getting FC levels all over the place. My first reading was 3ppm, which was lower than I expected. I figured I'd see about 4.5 ppm. So I checked again, ... and again... and again. I did at least 4 checks (sorry, didn't record them), and saw a low of 3, and a high of 7. While getting these results I experimented with just how 'heaping' my scoop of R-871 was, as I'd read the detailed instructions indicating that too much ("within reason, " whatever that means) is fine, but too little is bad.
I cleaned everything up and went inside without adding any bleach.
This morning, I did it again, and got 3.5, 4, 4, and decided to go with the 4, and added the indicated 2qt 1cp (72oz) of bleach.
My question is, have others seen such wild fluctuations in their FAS-DPD testing results? Any ideas what would cause that? Bad reagent, maybe? (My kit is fairly new - I think I bought it in June).
Up until now, I've never bother repeating the tests like that - just do it one and trust it.
Thanks
for your cya or above to ensure u don’t broach minimum before your next dose. As u learn your pool’s consumption based on use & season u will be able to go a couple days between doses if u adjust them accordingly. 
& replace it with a saltwater chlorine generator - steady dosing like a liquid dispenser but no jugs to lug. You would want a system rated for at least 2x’s your pool volume so 40k gal or more.