FC dropping in TX - I'm stumped

[BMICHELLEM85]

We just put up and filled our pool this past Saturday. I opened my 3rd large bottle of bleach tonight. I feel like I'm having to add quite a bit each night to keep my FC levels up. Here's what I'm looking at since last night...

Wed PM -- Th AM -- PM
FC - 10 --- 9.5 --- 4
CC - .5 --- 0 --- 0
pH - 7.5 --- 7.5 ---7.5
TA - 340 - didn't retest
CH - 60 - didn't retest
CYA - 30 - didn't retest - consistent reading for previous 48hrs

Temps over 100 today. Water temp about 92. Pool gets about 10-11 hours of sun. Water is clear and sparkley...in my opinion.

Does a 5.5ppm drop in FC seem normal during the day? If so, I would have to add enough bleach to raise my FC to 10ppm each night so it doesn't drop below my target (4ppm) by the following evening. I know 2ppm is my minimum but my best bet would be to keep it closer to my target right? Before last night I was raising my FC to 6ppm each night but would end up well under my target by the end of the next day. This disproves my theory that I'm adding too much and it's burning faster...right? Right? lol And I passed the overnight test by only dropping .5ppm right? Help please!! Do I need to increase my CYA? And adjust my FC target accordingly? That's what is floating around in my head but I'm too new to be making decisions like this on my own. lol

I added enough bleach to get me back up to 6ppm for the night since I won't be going back out. And I'll be home all day tomorrow to do what I need to with it.

 

[anonapersona]

You lost a bit more than half the chlorine during the day, so start at 5 and you should end above 2. Or add a bit more stabilizer to get to 50 and see what your % loss is.

 

[BMICHELLEM85]

But I was previously ending each night with 6ppm and it would drop to below 2 by the next evening. ??

 

[woodyp]

Isn't Texas fun! Your pool sounds like mine to the T. I'd raise my CYA to 50 and see how much that helps. With the heat we've had and pool temps............I still lose around 4 ppm per day with cya around 50. Guess I'm just too hard headed to go to 60 like we both probably should. Aerating my pool overnite now to drop some of that heat too. That may get pretty regular.

 

[anonapersona]

OK, new data. It appears that you do not have organics in the pool from the change on chlorine overnight. So daytime chlorine loss is sun and temps, though aeration can affect it as well if you are running fountain or such. Or heavy use. Or grass in pool. Or dog swimming.
Still given the sun here,a higher CYA is suggested.

 

[BMICHELLEM85]

Gotta love Texas! Hotter than hades and takes forever to get anywhere. lol

No aeration as of yet...no heavy use (or any today at all for that matter)...no grass or any other vegetation...no dogs. I will try increasing my CYA to 50 as suggested. And will start aerating as well...this will give me a chance to work on lowering my TA also, though I know it is a slooooow process. Decrease pH and TA with muriatic acid...increase pH by aeration...repeat...right?

Thanks for the help!

 

[anonapersona]

Or you can just test pH daily and when it hits 7.8 add MA to reduce to 7.2. Takes longer but still works. With no aeration going on, pH for you may not be the big deal it is for me.