Have a couple questions before going borate...

[jimhokie]

I still need to score 5 more boxes of borax after cleaning out 2 different Walmarts 3 times, and have 8 gallons of MA on hand. First, following the sticky for adding the borax and acid, I need to adjust my TA to between 70-80. It is currently about 90 to 100, and my pH is 7.5. I understand the procedure to lower TA is to add acid to drop the pH to 7.0-7.2, then aerate to bring the pH back up and lower TA. So how many iterations of this process will it take to drop my TA by about 20, and how long does the aeration process take for each iteration? I know this will be dependent on how I aerate, but are we talking hours or days typically?

What is the risk/problem if the TA is higher than 70-80 when adding the borax and acid? My TA tends to slowly drop during the season, I think because of adding new water that has low TA. Would I be OK to add the borax and acid now, and let the TA drop on its own over time to the 70-80 range?

Also, after reading probably a couple hundred posts on the borate topic today, I ran across at least a couple where people mentioned having to add acid every couple days to maintain pH after even switching to borates. I'm confused about this because I thought one of the main advantages of borates was to buffer pH. Since initially balancing my pool after opening a couple months ago, I have not had to adjust it at all...it started about 7.2, and knowing that it tends to increase, I let it do that and it has only now gotten up to about 7.5. I don't want to make a change to my pool that will increase how often I need to add chemicals. I'm primarily hoping for the benefit of decreased risk of algae bloom by adding borates. (I've already had one last week after a bad storm blew all kinds of debris into the pool and it was a couple days before I could clean it out, and I didn't crank up the SWG in the meantime.) Is it just an odd situation that would require someone to still have to add acid frequently after going borate?

 

[JasonLion]

From your description, you don't need to add acid. Adding borates won't change that, hardly every adding acid will remain hardly ever adding acid.

Lowering TA is still possible after adding borates, it is just rather more annoying. By the by, you only need to lower TA before adding borates if you were going to be lowering the TA anyway. There is no reason to lower TA simply because you are adding borates. But if you are lowering TA, then do it before adding borates.

The whole lowering TA process takes time, but it is impossible to predict how long. You don't need to lower TA all that much so I would guess several days, but it could be hours or weeks depending on how much aeration you can create and how much attention you pay to the pool.

 

[jimhokie]

Thanks for the response, Jason. Let me clarify, are you saying I don't necessarily need to adjust the TA to between 70-80 per the borate adding instructions if that's not where it needs to be based on other factors? My SWG instructions say to have the TA between 80-100. The Taylor test kit instructions say 80-100 if using calcium hypochlorite, and 100-120 if using dichlor, trichlor, or chlorine gas. So since the SWG generates chlorine gas, that would give me the 100-120 requirement. I've been aiming for 100 as a happy medium for these differing criteria. I am currently in the range of 90-100*, which is good by the SWG criteria and just on the low range by the Taylor criteria for chlorine gas. As I understand it, the borates will slightly raise the TA, probably getting me more solidly at 100. 70-80 would be on the low side of both of these criteria that apply to my pool.

So am I safe to use borates and continue to target a TA of 100?

* I say my TA is in the range of 90-100 based on the fact that the test solution begins to change on the 9th drop and completes the change after the 10th drop, so I interpret that as meaning the true value is somewhere in the 90s. Am I thinking right here?

 

[JasonLion]

You are bringing in a lot of factors that have nothing to do with anything and making it all more complex than it really is. Forget what other people say, and look at our recommendations in Pool School. There are all kinds of wild and silly recommendations out there, including from reputable sources, that you will never be able to reconcile. You have a SWG, which is not chlorine gas, it is a SWG.

With a SWG you want TA between 60 and 80. Since you are going to add borates and have a SWG and your TA is too high, you should lower the TA before adding borates.

On the TA test, add drops until the color starts changing, then continue adding drops as long as the color continues changing. The final drop, which does not change the color any further, does not count. That means your TA is 100.

 

[jimhokie]

Thanks for the clarification. I was presuming that the SWG actually generated Cl gas that is quickly dissolved in the water, so I was going by the chlorine gas guideline per the Taylor test kit instructions. As of today, the TA is down to 90 and the pH back up to 7.5, so I added another dose of acid and will continue to aerate. I also scored the last 5 boxes of borax I needed and borate test strips, so I'm ready to go as soon as I get the TA in range.

Just as a baseline measurement, I used a test strip just to check that is showed 0 since I've never added borax before, but it was actually spot on the 15ppm color. I've read that some people seemed to get bad batches of test strips, so I wonder if I got some old stock. I'll test again when I should be close to 50 ppm based on the amount I'll add.

 

[JasonLion]

Technically a SWG produces chlorine gas, hydrogen gas, and hydroxide ions. The net reaction is essentially PH neutral (once you take into account the breakdown of the chlorine produced), which is very much unlike adding chlorine gas to the pool alone.