Sorry for another round of questions, but I'm in a bit of a quandary. So when I started following this new process I started with 8.25 bleach. I had bought 3 cases at Costco (so 9 jugs). I decided to start going with the Lowe's brand Ket-Tek, because it was 10% and actually a full gallon versus 121oz like the regular bleach. Cost wise and convenience wise this made sense. When I was using the 8.25 my FC numbers were pretty close to what I thought they should be after adding an appropriate amount. But starting this weekend I ran out of 8.25 and started using my Kem-TeK 10% this week.
My numbers were off Monday and Tuesday with FC shooting up higher then I expected. So yesterday I wanted to be extra careful on all my measurements and be sure to take my time doing my tests. I'm using 19,800 for gallons as this comes from the pool builder and it seems to be right for other chemical additions and previous 8.25% bleach. Here are the numbers I got
Tuesday night final reading was FC=13 around 5pm
Weds initial reading FC = 8.5 4:30 PM (barely any color before adding last drop)
Add 32 oz 10% measured in a Pyrex measuring cup.
Predicted ~FC 10 (+1.3)
Actual reading FC=11.5 5:30 PM
Pump running the entire time.
It seems like this should be out of the margin of error (double the expected change). I ordered a speed stir to help on the measurement. Should I chalk this up to inexact test measurements? I do tend to add 2 drops at a time and then swirl until I get close to where I think it should be. I didn't think this would matter, but maybe it does. Hoping the speed stir will help with that. I had more out of whack numbers before that but was less exact in my chlorine measurement (Tues 8.5 -> 13 after adding about 36 oz)
I supposed the gallons could be off but I don't think by enough to make this kind of difference. Seems like it can only be 1) Gallons incorrect 2) Bleach % too low 3) My measuring cup is wrong 4) Operator error 5) PoolMath is wrong - that could be operator error as well
Usually on this kind of thing I tend to go with 4. I will note, that I user a syringe to get my test sample as exact as possible. This was 3 days in a row the FC went significantly higher then expected. If it was test error you think it would either be random error or I'm doing something wrong and both numbers would be off in the same direction either both high or both low. Also note that repeating the test (with same sample water) gives the same result. I'm getting the water from between a skimmer and return in a different location from where the chlorine was added.
For reference my other numbers
pH = 7.5
TA = 70
CYA = 60
CH = 240
I'm running low on R-0871 because I've done so many test at high FC levels, but I ordered a large refill. I'm expecting that today. So my next plan was to do several test samples from different regions in the pool. Maybe the chlorine is concentrating in an eddy where I take my sample.
My wife is starting to think I've become obsessed, which might be a little true.
My numbers were off Monday and Tuesday with FC shooting up higher then I expected. So yesterday I wanted to be extra careful on all my measurements and be sure to take my time doing my tests. I'm using 19,800 for gallons as this comes from the pool builder and it seems to be right for other chemical additions and previous 8.25% bleach. Here are the numbers I got
Tuesday night final reading was FC=13 around 5pm
Weds initial reading FC = 8.5 4:30 PM (barely any color before adding last drop)
Add 32 oz 10% measured in a Pyrex measuring cup.
Predicted ~FC 10 (+1.3)
Actual reading FC=11.5 5:30 PM
Pump running the entire time.
It seems like this should be out of the margin of error (double the expected change). I ordered a speed stir to help on the measurement. Should I chalk this up to inexact test measurements? I do tend to add 2 drops at a time and then swirl until I get close to where I think it should be. I didn't think this would matter, but maybe it does. Hoping the speed stir will help with that. I had more out of whack numbers before that but was less exact in my chlorine measurement (Tues 8.5 -> 13 after adding about 36 oz)
I supposed the gallons could be off but I don't think by enough to make this kind of difference. Seems like it can only be 1) Gallons incorrect 2) Bleach % too low 3) My measuring cup is wrong 4) Operator error 5) PoolMath is wrong - that could be operator error as well
Usually on this kind of thing I tend to go with 4. I will note, that I user a syringe to get my test sample as exact as possible. This was 3 days in a row the FC went significantly higher then expected. If it was test error you think it would either be random error or I'm doing something wrong and both numbers would be off in the same direction either both high or both low. Also note that repeating the test (with same sample water) gives the same result. I'm getting the water from between a skimmer and return in a different location from where the chlorine was added.
For reference my other numbers
pH = 7.5
TA = 70
CYA = 60
CH = 240
I'm running low on R-0871 because I've done so many test at high FC levels, but I ordered a large refill. I'm expecting that today. So my next plan was to do several test samples from different regions in the pool. Maybe the chlorine is concentrating in an eddy where I take my sample.
My wife is starting to think I've become obsessed, which might be a little true.
