Optimum TA Level before Borates

[Telnet64]

Hi - I have been using the TFPC method for about a year now, with terrific results. My water balance has been good with the use of the Stenner pump (although I just had to replace it after about 8 months use - for the first 4 months added bleach manually) and I have to add acid 2-3 times per week to lower pH.

My current levels are:
FC 4
CC 0
TC 4
pH 7.5
TA 120
CH 340
CYA 40-45

Since the Pool Calculator recommends 70-90+ for TA, when it gets down to 80 or so I add baking soda. I recently added some and it is a little high now at 120. I have Aqua Blue Pebble Sheen and the recommended level on their website is 80-120, so I overshot with the baking soda. When reading the lengthy post on adding borates in Chem 201, it is often mentioned that people keep TA at 50-60 and this seems low. Is there an advantage to keeping it below the "recommended level"? I know for SW pools the target level is lower, but I thought I saw this mentioned for plaster/pebble pools also.

Since the pool is now one year old, I am thinking I would like to add borates to see if it reduces my acid utilization and since the TA is more difficult to adjust after adding the borates, I would like to understand the best TA level first.

Thanks for any assistance!!

 

[Abigail K]

1) Our current recommendation is to use Pool Math instead of pool calculator as it is more up to date
2) Keeping TA below 70 would help to prevent pH fluctuations
3) I would recommend letting your pH drift to 7.8 and see if it holds there
4) You may not need borates

 

[Telnet64]

Thanks for the reply!

I appreciate the advice, however, I am still confused on the TA level:

Pool Math says "TA Goal: 70 to 90+". PebbleSheen website says "80-120". In the initial post of the 27 page sticky, it says "First, adjust your TA to your target value. (This is actually the hardest part of this whole procedure.) This should be around 70-80 ppm for SWGs and liquid chlorine (or bleach)..." Some posters in that sticky (usually with SWG) may say they have TA 50-60, others say they are 90-100.

To be honest, I don't understand if there is a possible impact on the PebbleSheen if I have a high/low TA level. From Pool School, I know that TA is a pH buffer and "At low TA levels, the PH tends to swing around wildly. At high TA levels, the PH tends to drift up."

So, it sounds like 70-80 is on the "low" side for non-SWG and will help the pH not rise to 8.0 - 8.2 (or more?) which is where it currently rises every 3-4 days (then I add MA), but I should drop the TA to 70-80 and see if the pH stabilizes at a lower level (7.8)?

I was interested in trying borates for not only helping to stabilize the pH, but also for the possible/potential feel and look benefits (#4 & #5 in Chem Geek's post #488 in the sticky).

 

[ping]

Try keeping the TA 70-80 range and let the pH run 7.5 to 7.8 and see how long you can go between additions. Let the pH rise above 7.8 to make sure it goes past 7.8 before lowering it to 7.5. You might be satisfied with the water using these parameters. Using these numbers, the CSI is fairly close to neutral and you should have no problems keeping the TA at 70.

Do you have any aeration in the pool that could be causing the pH to rise such as a waterfall?

If you go the borate route, lower the TA to 70/80 before adding them to the pool.

 

[Telnet64]

Thanks. that helps. Yes, my spa has an overflow into the pool.

 

[ping]

I have my spa adjusted so it just trickles down the wall and doesn't aerate the water very much.