Pool Store vs Test Kit Results??

[hawkeye91]

Hi everyone --

Got my Taylor test kit today - here are the results from tonight...

pH = 8.0 (has been 7.5-7.6 with HTH kit for days)
Acid demand = 3 drops
FC = 6.4 (was 15 this morning with HTH kit)
CC = 1.0
TA = 125
CH = 700 (!??)
CYA = 60

Based on a CYA of 60, a FC of 6.4 would be right in the middle of the ideal range per the best guess CYA chart. Would that be high enough to throw the pH off, or is the 8.0 likely valid?

Scott

[Watermom]

A cl reading of 6.4 should not affect pH readings. With a CC reading of 1.0, you are fighting something in the water and need to shock this pool and try and hold the cl at shock level until you can go from sundown to sunup without losing more than 1ppm of cl. Run your pump 24/7 for now. Wow! CH of 700? No using cal-hypo in this pool. Also, with a cya of 60, you don't want to use any trichlor pucks or dichlor powder. They will make the cya go up and you don't want it any higher. Stick with bleach.

How ya like that new kit?

[hawkeye91]

Love the new kit! It will be much easier to get a handle on things now. Of course I don't need to tell you that. =)

Morning numbers...

pH = 8.0+
Acid demand = 3 drops
FC = 6.0 (so lost 0.4 overnight)
CC = 0.5

I added acid this morning, but no bleach because I wanted to get a true picture of what was going on with the FC/CC.

Evening numbers...

ph = 7.5
FC = 4.0 (so only lost 2 ppm during the day as opposed to the 9 that the HTH kit was reading - what a piece of junk!)
CC = 0.5

I'm definitely going to add bleach tonight, but do you still think I need to bring it up to shock level, or just bring it up to 10.0?

Thanks!

Scott

[Watermom]

I think if it were my pool and I had a CC reading of 1 less than 24 hours ago, I'd go ahead and shock it up one more time. Then, if you still have less than a 1ppm loss overnight, then let it drift down and I think you'll be good to go. (You are probably ok not to shock, but it is just kind of like insurance. Won't hurt.)

[hawkeye91]

Makes sense, so I added enough bleach last night to increase the FC to 18. This evening's results...

FC = 10
CC = 0
pH = 7.9
TA = 110
CYA = 60

I was unable to test this morning, so I'm not sure how much FC was lost overnight versus how much was lost during the day today.

I biffed on the pH -- added some acid to drop the TA and aerated at the same time. I've since read in a couple of posts that I should have dropped the pH first, and then aerated which I will do from now on. But it does bring up a couple of interesting questions...

1. The Taylor book says that the pH reading should be accurate as long as FC is 10 or less. Do you find that to be accurate? Since I'm right at 10, could that be causing an artifically high ph?

2. Any idea how quickly aeration increases pH? I added enough acid last night to drop it to 7.2 so something seems a bit off here. At least I dropped my TA by 15 points. =)

I know I should probably only tackle one adjustment at a time (yes, I'm certain I learned that in chemistry class a long time ago); but, the trial by fire has been kinda fun.

Scott

[aylad]

I have measured accurate pH with chlorine levels higher than 10 with a very similar kit to yours (that uses Taylor reagents), so I think that you're probably getting an accurate pH reading with your chlorine at 10. As far as how quickly aeration raises pH, that depends on the pool and the amount of aeration (and some on the level of TA itself). A waterfall would definitely raise pH by aeration quicker than a return pointed upward. I find that a pool full of 10-year-olds raises it rather quickly!

Janet