Moving towards borates - lowering TA and increasing CH

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J

jleonard

0
Mar 9, 2008
11
Peachtree City, GA
I have started preparing my pool to add borates. Using the info in the recently posted sticky (good timing!) I am starting with step 1: reducing TA.

[Sorry for the long post - my questions are at the bottom, but I believe this background is important for the questions.]

My pool 35000 gal, SWG, pebbletec, jacuzzi spillover into pool (aeration), DE filter.

My numbers yesterday (4/26, using a TFTKIT):

FC 1.0
CC 0.0
PH 7.8
TA 130
CH 210
CYA 48
Salt 3400 (according to the SWG monitor)
Salt 4490 (tested with Aquachek strip)
BOR ? (ordered the LaMotte test strips yesterday)

Based on input from the my previous postings, my targets are:

TC 4
PH 7.6-7.8
TA 70
CH 400
CYA 70
BOR 50

Last night I turned off the filter, added 1 gal of acid in 1-pint globs scattered around the deep end (kinda cool to watch them dissipate), gave a light brushing to lower the concentrations near the bottom, and let the pool sit.

This morning (4/27) after running the filter and our built-in water mixer (a Riverflow swim jet), my numbers are:

TC 2 (I also bumped up the SWG yesterday)
PH 7.2
TA 100
CH 210

This morning I also increased aeration by adding a shower head to a bubbler in our shallow end.

QUESTIONS (Finally)

1) Can I add the BORAX now, or should I demonstrate patience and wait until my TA is at it's target. It looks like it will take another 1-gal of acid to drop the TA to 70, but I have to wait for the pH to rise, either through aeration or by adding something. Adding the BORAX will increase the pH, which is what I want. I have 4 boxes (16-lbs) ready to go.

2) How do I increase my CH? Should this wait until I have my borates at their target, or can I fiddle with this at the same time.

3) Is it OK to live with my salt at their current levels? I hate to drain 25% (or so) of my pool. I live near Atlanta and we're under watering restrictions.

Thanks for getting this far in my long message!
 
You should always have the pump running when you add acid. It is best to add acid by pouring it slowly in front of a return jet. You can also pre-mix it with water and then distribute it around the pool, but in any case leave the pump running while adding acid and for at least an hour afterwards.

You can work on CH at any time. It doesn't interact with lowering TA or adding borates. I suggest using calcium increaser from a pool store. It is possible to use calcium chloride, sold as a deicer, but it has gotten difficult to find it pure enough for pool use.

You should wait till the TA is where you want it. It will be far more difficult to lower TA after you add borates.

Your salt level is fine with almost any SWG. Actually, since the SWG hasn't complained about the salt level it is definitely alright.
 
I was researching procedures for lowering TA and ran across a link that offered this suggestion "by creating pockets of extremely low pH temporarily, you will burn off the alkaline materials in those areas, thus bringing down the Total Alkalinity reading of the pool." There is a bit more to it, so here is the link:

Adjusting TA by Pool Plaza

I gather from your response that this is not a good idea, and that the same reduction in TA can be achieved without "creating temporary pockets of low pH."
 
This is the 'slug method' of reducing TA that is firmly entrenched inthe pool industry.
The fact is it does not work.
Adding acid lowers TA whether you slug it or dilute it. Pouring undiluted acid into your pool creates pockets of undiluted acid that sink to the pool surface and sit there possibly causing damage. There was an interesting research paper along with videos where a dye was added to the acid that verified this.

Adding acid lowers TA, period! It also lowers pH so you don't want to add several gallons all at once.

WARNING--CHEMISTRY ALERT!!!!!!!!! :shock: :shock: :shock: :shock:

It converts the bicarbonates in your water (what we measure as TA) into carbon dioxide gas dissolved in the water or carbonic acid (which is NOT measured by the TA test), basically the same thing as club soda!
Aerating the water will drive off the carbon dioxide much like shaking up a bottle of club soda. This causes the pH to rise.
(This will also happen to a bottle of club soda if you shake to make it flat--it's pH will rise.)
Here is the reason:

Carbonic acid is basically carbon dioxide dissolved in water so the aeration is actually lowering the amount of carbonic acid (Key word here is acid-- less acid means higher pH) WITHOUT converting it back into bicarbonates (which means the pH does not rise). If you add a chemical to raise the pH all you do is chemically convert the carbonic acid (carbon dioxide in the water) back into bicarbonates so the pH AND TA rise. By aerating you are removing the carbon dioxide from your pool so it cannot convert back into bicarbonates.
 
Patience or fun. For aeration, just turn your pool into a wonderful set of fountains, showers, etc. turn up the returns to have them break the water surface with the pump on high, and have a pool party with lots of kids who are encouraged to splash a lot, especially if they can cup their hands and create lots and lots of underwater bubbles. Have a contest for who can create the most bubbles. (If you've got people in the water, then your low end pH target should probably be 7.2 instead of 7.0).

Lowering the pH with acid is easy. It's aerating the water to make the pH rise that is the slower part of the process.
 
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