CH and TA Rising?

[rtkane]

Hi all,

When I opened the pool this year, I had significant scaling (full details in this post from June). After finally learning how to take care of my pool in Pool School, I've had really great results. Levels have all been good as I test pretty much every two to three days since I've "gotten to know" my pool pretty well (to the point where I can pretty much predict what the results will be).

I have, however, had my CH rising. It's gone from 275 in June (after a 50% drain) up to 475 today. Most current readings as of this morning:

FC - 5.5
CC - 0
pH - 7.8
TA - 80
CH - 475
CYA - 55
Borates - 50

Can the CH readings still be jumping up from leftover scale coming off the walls? I've noticed that after we did our treatment, we had some rough spots still, which have gotten somewhat better. My CSI hasn't been overly negative except when I've used MA to drop my TA (pH goes up pretty quick in my pool even without aerating--I've tried to drop TA to 60, more on that below) so I wouldn't think it'd be leeching out of the plaster. I haven't added anything else other than throwing in some leftover dichlor occasionally to bring up the CYA (I have an SWG) and the occasional dose of Jack's Purple Stuff to ensure the copper is sequestered (we had minor copper staining).

Now for the second question...my TA continually rises...what could cause that? Because my pH goes up pretty quickly, I added borates to the pool and try to maintain a low TA (around 60). However, I still need to use a gallon of MA a week to keep the levels in check and inevitably, my TA goes up to 80 in a week or so, at which point the pH rises much more rapidly.

Finally, I'm right now in the process of doing a partial drain again to drop the CH to a more reasonable level (probably around 300-350) so that when I winterize, I don't have to worry as much about scaling. If the Pool Calculator levels show it as being balanced (CSI of .07 with TA of 80 and -.03 at a TA of 70) should I even be worrying about CH? My biggest concern is to NOT have to go through the scaling I had at the beginning of the year after we shut the pool down this winter.

Thanks!

 

[duraleigh]

What is the CH of your fill water? Evaporation and splash out could account for some increase but usually not that much.

Your pH is too high. With high CH, I would keep the pH around 7.2 - 7.4 and that will do more to protect from scaling than about anything.

 

[rtkane]

What is the CH of your fill water? Evaporation and splash out could account for some increase but usually not that much.

Your pH is too high. With high CH, I would keep the pH around 7.2 - 7.4 and that will do more to protect from scaling than about anything.

CH of our fill water is 50 (so I'd figure that replacement for evaporation and splash out would actually lower it).

When I add MA, I drop it to 7.2 and by the next morning it's back up to 7.4 or 7.5. It's almost impossible for me to keep it 7.4 or below without having to add acid every single day--besides the fact that I hate dealing with MA, it's just impractical for me to micro-manage it at that level. It then slows down and gives me a couple days at 7.7 then a few more at 7.8, at which point I drop it again. I am doing a partial drain of about 1/3rd of the water right now, so hopefully the pH my pool wants to stay around (upper 7's) will work long term with the lowered CH.

If I was able to keep it lower, when I plug in 7.2-7.4 for pH into pool calculator, (with an average TA of around 70, which is typical), I get a CSI of -.36 to -.53. Isn't that far too low for a normal "maintenance" level where I'd then have to worry about etching? I'm not as concerned about the scaling while I'm actively managing levels, but rather when I put the pool to bed for the winter and can't make changes to the pH. I know a lot of my pH rising issues are due to the SWG, so hopefully that won't be as much of a problem over the winter--does pH typically stay constant after a pool is winterized (with the exception of rain affecting it)?

Thanks for the reply...

 

[Richard320]

If your scale is coming off the walls, I'd say yes.

My CH continues to rise even when I haven't added any water. My pH requires acid on a regular basis, like yours, even though I keep TA 50-60. And I can see the shadowy scale I've been fighting for a couple years shrinking in size even though CSI is usually only about -.3

 

[rtkane]

Thanks, Richard. I just finished up my partial refill so hopefully that will put me back in a decent CH range.