pH Creeping up

[dapeterson]

Hi everyone,

I am truly enjoying my TFP thanks to this site! I just have one minor issue that I can't figure out. My water has been balanced and crystal clear for the past 6 weeks. I recently added borax and have been pleased with the results. However, my TA is creeping up rather quickly (at the rate of about .2 per day) I have a waterfall, but this is without the WF running.

Here are my results:
FC - 4 (never below 2)
CC - <.5 (always between 0 and .5)
pH - 8.0 (trying to keep it at 7.5, but I ran out of MA to bring it down)
TA - 70 (typically low, between 60 to 70)
CH - 380 (was down to 360 but I think its being re-absorbed from the deposits on the plaster)
CYA - 20
BOR - 40

16, 000 gal, in-ground, plaster, cartridge filter

Any ideas?

Much appreciated!
Dave

 

[Bama Rambler]

How much fill water are you having to add and what's the TA of it?

 

[frogabog]

What was the pH before you did the borates? Did pH respond appropriately to the acid while adding borates? Is there a reason you stopped at 40ppm?

Couple things I noticed in your results:

1 - CYA is low. Even for a pool that gets little or no sun, CYA of 30-40 is better. I'd bump that up at least 10ppm right away.

2 - TA of 70 is just fine. Especially with borates. You could even add 10ppm more borates. I know that the visual difference between 40ppm and 50+ppm borates is significant. Once you hit 50, you'll actually see the sparkle of a borated pool. It's especially pretty at night.

3 - pH is going to be harder to move with borates. So expect that. However, once you get it dialed it shouldn't rise as fast either. It's not going to eliminate the need for regular acid, but it should reduce the frequency overall.

 

[dapeterson]

I didn't think about that, but I have an auto fill. If I remember correctly the fill water is 110 TA. The pH was high on the fill as well, but I can't remember the reading. I'm certain it was over 8.

That may be the issue. I'll try to shut off the AF and see what happens.

One more question: How can I keep the TA in the appropriate range, if I need to keep adding MA to drop the pH?

Thanks!
Dave

 

[dapeterson]

Thanks frogabog!
I'll bump the CYA. I've been dumping water to get rid of CH and CYA takes a hit each time. I just haven't gotten it back up yet. Chlorine usage seems to be fine, even though the pool receives sun all day so I wasn't too worried.
I stopped at 40ppm borates because I didn't want to miss and go too high. I just never topped it off. pH was 7.4 and TA was 70 when I added borax. I added the acid then the borax per instructions here and it seemed to respond appropriately. I'll add the additional 10ppm tonight.
Dave

 

[elwood58]

Unless you are using a great deal of fill water, your pH and TA should be fairly manageable. Just make a point of knocking pH down to 7.2 once in a while. Maybe even aerate it back up right after. This will give you a good TA drop each time.

 

[dapeterson]

What if TA is already below 70 when I need to drop the pH? Should I be concerned about low TA?
Thanks!
Dave