New Fill Ph And Ta Reading 0! Help Please

[Venams]

Just restarted my tub after a leak during the winter weather. It was 50 here yesterday so took advantage of the warm weather to refill tub.

Sunance Optima so near 500 gallons on a fill.

Reading my notes from previous tub balances using my Taylor FAS DPD kit I believe that I used 2 cups muriatic followed by another 2 cups muriatic to bring the TA and PH in line.

So this time did same. Uses 12 oz of Metal-X to deal with the high minerals. Then added 2 cups muriatic, and another 2 cups muriatic about 4 hours later.

Tried testing TA but by the time I added 5 drops R-008 and the solution was red from the first drop (test kit said it should be green). I read the intstructions but it doesn't say what to do if water is red?

Used my quick dip test strips and TA - PH etc reads low and TA shows 0 :-O

How do I fix this?

[Spanky]

4 cups (1 liter ) of muriatic? What was your pH at the start of the fill? If i had to guess i'd say your pH is now dangerously low and ouside the range of the test reagents. Check your pH ..... you may need an OTO test if the actual pH is outside the range of the Taylor test

[Venams]

 

4 cups (1 liter ) of muriatic? What was your pH at the start of the fill? If i had to guess i'd say your pH is now dangerously low and ouside the range of the test reagents. Check your pH ..... you may need an OTO test if the actual pH is outside the range of the Taylor test

 

I didn't take readings to start as I was going off my previous measurments of Total Alkalinity and my tap water. I believe my tap water Total Alkalinity was in the range of 380PPM.

Shouldn't I add baking soda to bring it back up? I just don't know how much to add?

[Venams]

I used the Pool Calculator and plugged in value of 7.0 for PH and TA of 0 (test kid showed Red and not Green so I'm assuming to add 0?)

So the TA portion advised to add .86 cup of Baking Soda. Did that and retested:

now TA=30ppm

PH still reading 7.0 (or lower; color is more yellow than lowest 7.0 reading)

Plugged reading into Pool Calc again and says to now add 4.7 oz of baking soda. The PH portion says to add 1.5 oz of Borax. Should I do the Borax and Baking Soda? I was under the impression that I would just need to add Baking Soda to bring PH and TA up?

[Venams]

OK So I was able to use muriatic to bring PH down to 7.5-7.6 and TA should be about 70-80PPM

I normally put 3 cups of Borax in on a clean fill (per WaterBear).

Question: Will the BORAX mess with my PH and TA and if so what do I have to do to compensate?

[Spanky]

Ok now that you tell us that you added borax on the initial fill the muriatic makes sense but for future reference stabilize the pH and TA before you begin to add borates. What is the pH now? If your borates is at 50ppm then use Washing soda to raise pH. Your target should be 7.6 to 7.8 not 7.0 Stabilize the pH then test the TA. If it's low add baking soda, if high then use muriatic/aearation to bring down to 50 . It's a step by step process unfortunately you cannot just add everything ogether like a cake recipie an expect proper results. Start with CH then pH then TA. Once stable then, and only then add the borax/muriatic which should be premixed in a large bucket before adding to the spa.

[Spanky]

Note I suspect that you may be confusing CH and TA I somewhat doubt your water has a TA of 380 but a CH of 380ppm does make sense.

[Venams]

Thanks Spanky. I didn't add the 3 cups Borax yet, I was just stating that I added the 3 cups borax on past initial fills but hadn't yet added it on this fill due to low readings.

As you said I was trying to stabilize PH and TA before adding the Borax.

I believe I added too much Muriatic Acid in the beginning (2 cups + 2 cups) which resulted in the low PH and TA readings. I then used the POOL calculator which advised to add baking soda after which I was able to get TA to ~70 and PH ~ 7.6

So it sounds like these are stable/balanced readings right? So now it's safe to add the 3/3.5 cups of Borax right? If this is correct will this change my TA and/or PH?

[chem geek]

Also note that The Pool Calculator won't be accurate for very large pH swings outside the usual 7.0 to 8.0 range. Yes, you added way too much acid in the beginning. Every 1.3 fluid ounces of full-strength Muriatic Acid (31.45% Hydrochloric Acid) in 500 gallons lowers the TA by 10 ppm. 1 cup lowers the TA by 62 ppm so your 4 cups of acid was way, way too much and likely exhausted the TA (2 cups would lower the TA by 222 ppm in 500 gallons) and had the pH crash to 2.6 or so.

If you are going to be using the Dichlor-then-bleach method, then a TA of 50 ppm would probably be better and then use 50 ppm Borates. Given how you swing the pH so wildly in your spa (and hopefully you didn't damage it) I would not add Borax for your borates since that would increase your pH significantly. If you were to add Borax, you have to also add acid and pair this off back and forth. I think you would be better off ordering boric acid instead since it won't cause pH swings so it's easier to get the borates up to 50 ppm. If you do go the Borax/acid route, then it's 3.5 cups of 20 Mule Team Borax and 14 fluid ounces of full-strength Muriatic Acid, but I'd split up the dosages into roughly quarters so add 1 cup of Borax and then 4 fluid ounces of acid three times back and forth and then a final dose of 1/2 cup of Borax and 2 fluid ounces of acid.

[Venams]

Thanks so much for the help/advice guys. I think I have the system down now

[Venams]

I just balanced water with ph of about 7.6 and TA around 70.

Checked CH and it's 30ppm. With all of the horsing around with Muriatic Baking Soda etc. would that make the CH drop? I'm asking because I didn't measure but from previous fills on our municipal water it was around 110ppm on new fill.

If it's too low how do I boost the CH?

[chem geek]

No, the CH would only drop from replacement with water lower in CH. Perhaps your fill water isn't as low in CH as before. You could test it to see.