Alkalinity in a tile pool question

[SharkinHawaii]

Hello all,

I had my pool resurfaced in January from plaster to tile. It's been a learning process these past few months, but I have adopted BBB and am moving boldly into my first Hawaii summer as a pool boy (ahem, pool serviceman). I have a few other posts on this site and believe that TFP has saved my life, or my wallet anyway....and therefor my marriage.

So, my question is regarding all tile pool surface and alkalinity levels. I have seen a few places online say and was told by a pool service place that it's a good idea to keep my alkalinity up at 150 ppm. This seems to be about keeping the tile attractive, but I get the impression from some reading that I need to be concerned with the grout, which is basically comparable to plaster.

From my own reading/studying, I believe I need a slightly negative CSI. Putting my alkalinity up to 150 would push my CSI positive, so I don't see the sense in that regard. Could anyone provide some wisdom on this?

My current readings:
FC 11 (Goal 11 with CYA 90)
CC 0
PH 7.6 (Goal 7.6)
TA 85 (after reduction of 30 for CYA) (Goal 70 - 90)
CH 290 (Goal of 300)
CYA 90 (Goal of 80, I'm in Hawaii)

 

[chem geek]

I can understand why you'd want the calcite saturation index to be near zero in order to protect the grout between the tile, but are there any specific reasons that were given as to why TA itself should be higher as opposed to having the proper balance of TA, CH and pH?

With an uncovered pool, the main issue with a higher TA (even if you had a lower CH) is that the pH will tend to rise over time, assuming you are using chlorinating liquid or bleach as your primary source of chlorine.

 

[Guest]

Keeping the TA at 150 is common practice IF and ONLY IF you are using trichlor for chlorination since it is very acidic and this will help keep your pH from bottoming out which could affect the grout. However, if you are using ans unstabilized chlorine source such as liquid chlorine or bleach or a SWG then you will be much better off running the TA on the low end (70-80 ppm) since this will increase your pH stability and lessen the likelihood of your pH spiking high and scale deposits forming on your beautiful new tile!

 

[SharkinHawaii]

Got it, thanks. Glad to be able to make sense of what seemed to be contradictory.