Low TA

[Plankton]

Edited for eye breaks..Butterfly


Hi All,

Its been a while since I have posted with a problem. I'm always on the forum and have learned a lot just by reading everybody else's posts and the advice given. That is proabably why I have not had to post as much! :-D A big thanks to everyone out there for the unsolicited help! :-D

Now I have a problem of my own and need help. As one of the other posts mentioned in the beginner forum, I also have just started to get a white ring around the pool and on my flagstone. It just started happening recently to the point that I have noticed it really bad. I have determined that it is calcium staining and it looks as though its going to be really hard to remove. I need to get it off to restore the look of my pool.

Here is some backround info on the pool. I purchased the house a year ago exact and the pool was fine all winter and summer without this problem. Although I was learning all the tricks and info provided by all the great people on this forum, I kept the balance of the water in check and just recently, (about two months) have I started to lag on doing all the right things.

I got switched to midnights so adjusting my schedule has been hard enough, much less trying to keep up on everything else. The only thing I can equate the sudden calcium scaling to is the fact that my TA has dropped considerably it is reading at 60.

Is there a correlation to the calcium deposits/rings and the low TA? Also what are the consequences of having it so low?

Since I use the BBB method, (another procedure I learned here) I will be bumping it up using baking soda, but any help I could get now would be appreciated. I have posted my readings below as to help with the answers. As always if you need more info from me please ask. Thanks again for all your help!

FC 1.5- Low- working on getting it back up.
PH 7.5
TA 60
CH 560
CYA 45-50 range
Pool Temp 55
Location- Northern CA
P.S. I'll post pics asap.

 

[spishex]

Someone else will be better able to answer your question regarding low TA and Calcium. If we're going by saturation index, a low TA would lead to less scaling, but again I'll leave that to someone you can tell you exactly what's going on.

However, 560 is a heck of a lot of calcium. Is your fill water very hard to begin with? Bringing that down will be a big help.

 

[chem geek]

Assuming the measurement numbers are correct, the saturation index for your pool is around -0.3 which is negative so should not be scaling. Though your CH is high, your TA is low and the temperature of the water is low. Since you don't see a roughness in the pool plaster itself but instead see a white ring around the pool and in the flagstone, perhaps (at least for the flagstone) it's efflorescence.

What is unusual in what you describe is that the TA dropped considerably recently. That usually doesn't happen unless you were adding acid (or using an acidic source of chlorine) at some point. Also, if you were adding acid because the pH was rising, then perhaps the pH rose a lot at some point which caused the calcium carbonate scaling. The water may have been warmer at that point as well. For example, if the water were 80F and the pH got to 8.0, then the saturation index would have been +0.4 (though normally scaling isn't seen until the index gets even higher, around 0.7 or so).

As for removing scale, either a dilute acid solution (make it very dilute initially so as not to damage the stone) or a CLR product will work.

Richard

 

[Plankton]

Butterfly- No problem- I should have known better!! Thanks!

Richard,
Your explanation sounds right- although I never let the PH rise above 7.8 during the swimming season when the water temps where up that high, but I have been adding acid lately to keep it under control. I should have mentioned that I use the TF-100 test kit for my testing and this is the second time I have tested for calcium. I tested once at the beginning of the season when I first received the kit.

Spishex,
I don't know if my fill water is high in calcium, that will be the next thing I will test. But since I have only really started to notice this recently, I don't think that would have a major effect of this. But then again I'm a beginner, so I will take all the advice I can get. Thanks.