Right borax? No borates test

rickv

Active member
Dec 1, 2017
29
western australia
Hi, long time low PH struggler. Jets that bubble son't do enough. Alkalinity could be a bit higher, so added some soda ash. But also considering adding borax.

Thing is, I don't have a testing kit for borates (taylors not readily available down under). We also don't have 20 mule borax. We have this:

I googled and in this pdf
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it says it's bealry pure Sodium tetraborate decahydrate ...something. is that a good alternative? How much do I put in there to raise the ph from 6.8 to 7.4 on a 33K liter pool?
 

ajw22

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What are you targeting for your pH and TA?

What was your pH and TA that you felt required adding soda ash?


Do you have borate test strips available?

 

rickv

Active member
Dec 1, 2017
29
western australia
TA between 25-50 (test kit goes in 25ppm increments, it tinished after two drops). I have a SWG. Target was 50-75.

PH was 6.8, target 7.3 to 7.4
 

mgtfp

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With just two extra ingredients, you can titrate for borates using the Clear Choice Labs reagents.

Here is a description:
After discussion with fellow member smackdab, it was decided that the test should be re-written to be more clear especially in light of some of his recent data on thiosulfate reductions of chlorine (dechlorination). See HERE - R-0007 FC drop in a sample size .

Equipment Needed
SpeedStir (is really, REALLY useful!!!)
50mL Beaker* (can be purchased on Amazon HERE)
A 1/8th teaspoon measure (can be purchased on Amazon HERE)

*The 50mL beaker can sit on the SpeedStir allowing easy mixing of reagents

Chemicals Needed
Taylor R-0007 - Chlorine neutralizer reagent
Taylor R-0009 - Sulfuric acid reagent
Taylor R-0010 - Sodium hydroxide calcium buffer reagent
Bromothymol Blue (BTB) - (See Post #134 where I show two different manufacturers)
Mannitol Powder - From Amazon HERE

Test Procedure (50mL Water Sample)***
1.) Collect a 50mL sample of pool water
2.) Add 2 drops of R-0007 to neutralize the chlorine
3.) Add enough BTB until the water turns to an easily visible blue color. The volume of BTB applied here will not affect the results of the test; it's just an indicator.
4.) Add enough R-0009 drop-wise to lower pH. You want the indicator dye to transition from blue to blue-green to yellow-green to straw yellow. Straw-yellow is the color one wants to see and it should take anywhere from 8-12 drops to get there depending on your starting pH and TA.
5.) Now add approximately 2 drops of R-0010 until the water just turns pale blue. This is the hard part - you want to get the indicator dye to just turn blue, like a baby-blue and not go all the way back to a deeper blue. Typically 2 drops is all that is needed.
6.) Add 2 level spoonfuls (1/4 teaspoon total) of Mannitol. If the water has boron in it, then the sample will turn yellow again.
7.) Add R-0010 drops until the water transitions from straw yellow to greenish-blue to baby blue, i.e., similar shade of blue from Step 5. Record how many drops of R-0010 are used in this step.
8.) Calculate ppm boron/borates by multiplying the number of drops of R-0010 used only in step 7 by 4ppm/drop in units

***Please note - This test protocol was done using my pool water where the following was present -

FC: 6ppm
CC: 0ppm
TA: 60ppm
CYA: 90ppm
pH: 7.6
CH: 1150ppm
Borate: ~ 56ppm
Temp: 85F
Salt: 3800ppm

Alternative Test Method Volumes

For a 25mL sample, each drop of R-0010 used only in step 7 equals 7.9ppm
For a 25mL sample, you will likely only need 1 drop of the R-0007


Notes:

*Dechlorinating the sample is important. The bromothymol blue (BTB) dye is sensitive to chlorine and will be bleached by it. 2 drops of R-0007 is usually more than enough for FC in normal ranges.

*If your pool water has high levels of TA (>100 ppm), I would suggest experimenting with the the number of drops in Step 4. It is important to get the sample down below the transition point for the BTB indicator and a high TA water sample might make it necessary to use a few more drops of R-0009 (See smackdab's analysis HERE). The presence of high TA will not affect the end result.

*The amount of bromotymol blue (BTB) used in Step 3 should be adjusted to give you the best color shade you can see. The standard BTB bottles in the chemical section don't use dropper tips but are rather more like squeeze bottles. So just add enough BTB so that you can see the colors.

*The R-0010 reagent (sodium hydroxide) has a very STRONG effect on raising the pH. So it should not take much to go from pale yellow to blue in Step 5. You don't want to overshoot this and add lots of R-0010 in this step. It would be easier if the R-0010 were less concentrated but we're stuck with what we have available.

*Yes, you have to try to remember the shades of blue unfortunately. This is a titration test where you are trying to measure something called the "equivalence point", i.e., the exact pH value where there's a sharp transition from yellow to blue. This is very easily see with a pH probe (which is what you would use in a lab) but it's much harder to do with a visual color determination. So what you're really after is that exact point when the BTB changes from a greenish-blue color to baby-blue as that is the point in the pH curve where the sharpest change occurs. If anyone is interested in the chemistry details, this website has a decent explanation -

Titration Fundamentals - Chemistry LibreTexts



Mannitol, I found at eBay in a 50g quantity:


And the BTB pH-indicator you can get in the pond section at Bunnings:


All the other ingredients are part of standard Clear Choice Labs kits. Here is a table showing the equivalents to the Taylor reagents:

I use the test tube that came with my smart stir, which holds 40ml. Scaling the test to a 40ml water sample gives a test resolution of 5ppm per drop.

The test is really easy and totally worth it.
 

mgtfp

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And regarding adding borates. Don't bother with Borax if you can avoid it. Boric Acid is much easier.

You can source boric acid here:

Or (I did that) get the Optimiser from Bioguard:


The Bioguard stuff is just 100% boric acid, a bit more expensive, but then you are sure that there are no additives that they sometimes add to boric acid when used as an insecticide.

The stuff from the first link is also advertised as 100% boric acid, and I think other Aussies here have used that source (same seller also on eBay). But sometimes there are additives in insecticides, and there was a Bioguard shop nearby where I could just pick it up.

But you really want to be sure that you have understood your water chemistry and have TA and pH where you want it to be before adding borates.

And forget about some of the borates miracles like "sparkling water" or "algaecidal properties" (only at much higher concentrations than considered safe for pools). But it does a good job buffering pH, especially when keeping TA below 70 and pH in the higher 7s.
 
Last edited:

brendio

Active member
May 18, 2020
30
Queensland, Australia
I got boric acid from an agricultural supply shop. Cheaper than any other source I could find for bulk quantities.

Boric acid will (slightly) lower your pH as well as increase buffering capacity. Borax will increase your pH.

It is interesting that you struggle with low pH with a SWCG. Most, myself included, struggle with the pH creeping up. Have you tested your fill water?
 

mgtfp

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It is interesting that you struggle with low pH with a SWCG. Most, myself included, struggle with the pH creeping up.

Good point. I was assuming, Rick was struggling with pH creeping up and wanted to add borates to slow down the upwards drift, hence the need for a test kit - adding a bit if Borax to increase pH from time to time doesn't really increase the borates level that much that testing is required.

pH drifting below 7 is really unusual unless Trichlor pucks are being used.

@rickv: It would be good to understand why your pH is so low.

If you really need to add Borax to increase pH (usually aeration should do the trick, even just pushing air in with the brush should raise pH very quickly when it is so low), it is important to have a full set of test parameters to calculate the required amount (with PoolMath). Especially TA and CYA are important to know, as they act as buffers. Depending on the exact values, it could be anything up to 2kg (I assume, the 33K are Liters, not Gallons?).

You can buy Borax at Bunnings, in the cleaning supply aisle.

Also consider that if your TA is closer to the 25ppm side, that you would have virtually no buffering capability in your water, esp if CYA is also low. You really need to do a titration with a 25ml sample to get a 10ppm resolution.

With a TA below 50, you will have large pH swings. Usually, the ups and downs by producing and using chlorine are negligible, the whole chlorination cycle is pH neutral. But with no buffering, your pH will significantly swing up when over- and significantly swing down when underproducing chlorine.

So, when you test pH right after a pool party with high chlorine demand, your pH might be lower than normal. Once that chlorine has been topped up again, pH should be higher again.

Would be good to do a few pH test throughout the day at the low and high points of your FC-level to understand if that is part of your problem.
 
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