How much Dry Acid (Sodium Bisulphate)

Denniswiseman · Postby **Denniswiseman** » Sat 08 Oct, 2011 13:14

I have been following the Dry Acid and Aeration protocol in this thread

My TA was around 180 and I have been adding 1 kilo (2.2 ibs) a time to reduce PH and TA, then I aerate
I have used about 6 kilos and my TA is at 138

The PH is reducing and being raised as it should

Am I useing to much PH reducer(sodium bisulphate) or is this the correct amount

Postby **chem geek** » Sun 09 Oct, 2011 00:27

Lowering the TA by 42 ppm using 6 kilograms of dry acid (93.2% sodium bisulfate) would occur in a pool that was about 55,000 liters (14,530 gallons). Is that your situation? You might consider using Muriatic Acid instead of dry acid so as not to increase sulfates so much. Your 6 kilos if in 55,000 liters would raise sulfates by 87 ppm. With Muriatic Acid, you would only be increasing chloride which is far more innocuous.

Denniswiseman · Postby **Denniswiseman** » Sun 09 Oct, 2011 04:38

Hi

Thanks for the info, this forum has taught me a lot. Thanks again

My pool is 45,000 litres
How can I tell the strength of my PH minus?
How do I get rid of the sulphates?

Postby **chem geek** » Sun 09 Oct, 2011 12:46

Your pH Minus should have ingredients on it somewhere and it will likely say "93.2% Sodium Bisulfate" though might have a lower percentage. As for sulfates, you can't get rid of them which is why you want to avoid adding too much in the first place. That is why using Muriatic Acid (31.45% or 20º Baumé Hydrochloric Acid) would be better. If you prefer Muriatic Acid that doesn't fume as much, then get half-strength (15-16% or 10º Baumé Hydrochloric Acid). You can use The Pool Calculator to calculate dosages.

Denniswiseman · Postby **Denniswiseman** » Sun 09 Oct, 2011 13:32

I dont think the pool calculator is 100%

Desired reduction in total alkalinity 40 ppm
Volume of the pool 45,000 litres
360 gr of dry acid (sodium bisulphate) is required

This was the result I got but I used 6 kilos to get about the same reduction

Try it

Postby **chem geek** » Mon 10 Oct, 2011 01:15

In the TA section for lowering it doesn't tell you how much acid, it just says "To lower TA you reduce pH to 7.0-7.2 with acid and then aerate to increase pH." In the "Effects of adding chemicals" section at the bottom if you put in 4600 g of "dry acid" then it says this lowers the TA by 40 ppm. I'm not sure where you got the 360 g. Of course, you don't add all the acid at once anyway and instead follow the procedure of lowering the pH to 7.0 and aerating, which is what you've been doing.

Denniswiseman · Postby **Denniswiseman** » Mon 10 Oct, 2011 04:08

I am referring to the Pool Calculator http://www.havuz.org/pool-calculators.htm
Origonally I was trying to work out the amount of Sodium Bisulphate to use

For 40 ppm in a 45000 litre pool the calculation comes up at 360 gm of Sodium Bisulphate

I've tried it on two different browsers and the result comes up the same

Postby **czechmate** » Mon 10 Oct, 2011 08:37

www.poolcalculator.com has all your answers for the proper pool chemical dispensing.

Denniswiseman · Postby **Denniswiseman** » Mon 10 Oct, 2011 12:07

I am quiet happy with the way my TA is reducing
I only wanted to point out that there is on error in the Pool Wizard

Postby **chem geek** » Tue 11 Oct, 2011 00:03

Thanks for pointing out that error. I wasn't even aware of that Pool Wizard calculator as I've always used The Pool Calculator.

Denniswiseman · Postby **Denniswiseman** » Fri 14 Oct, 2011 13:28

I have managed to get my TA down to 100ppm & 7.4PH using the acid/aeration method.
I would like to let you know that the pond aerator worked a treat and I would recommend it as an alternative if you don't want to cool the water.
I run it all night with a thermal cover on then I remove the cover in the morning.
It is cheaper to run than the filter pump

Postby **chem geek** » Fri 14 Oct, 2011 19:19

Thanks for letting us know. I'm surprised this worked with the pool cover on but perhaps the air was able to escape from under the cover since it has to go somewhere. When one wants to prevent pH rise from outgassing, one can put on a pool cover, but in that situation one is not injecting air into the pool.

Denniswiseman · Postby **Denniswiseman** » Fri 02 Mar, 2012 09:23

Hi

I am now completely over to Liquid Chlorine, Hydrochloric acid and Aerating.
All are working well but I have a few questions

Does Sodium Hypochlorite increase TA at all, as mine seems to be rising with no other chemicals being added
Is is OK to pour the Liquid Chlorine and the acid in the skimmer while pumping
I'm pouring it in over the return eyeballs at present but feel it would get a better distribution through the filter system

Postby **chem geek** » Sun 04 Mar, 2012 12:53

Sodium hypochlorite (chlorinating liquid or bleach) has some excess lye in it so can slowly increase the TA over time, but how much depends on the specific product you are using. 6% Clorox bleach has the least amount of excess lye in it so has minimal net pH and TA rise over time -- it has a pH of around 11.9. Some off-brand bleaches have a pH of 12.5 or more. Good 12.5% chlorinating liquid has a pH of around 12.5 while some lesser brands have a pH of 13.0 or more.

The TA can also rise from evaporation and refill with fill water since fill water has TA (and usually CH as well). If you find that your CH is also slowly increasing, then it's more likely to be evaporation and refill.

In general, you do not want to pour concentrated chemicals into the skimmer. This is most certainly the case with strong acid since it can damage pool equipment such as heat exchangers and pump seals. Chlorinating liquid or bleach won't be as damaging but it's still not a good idea since it is a strong oxidizer, certainly not to do on a regular basis. Baking soda and cyanuric acid are OK to put into the skimmer (the CYA will get caught in the filter and slowly dissolve there). If you pour your chlorinating liquid or bleach slowly over a return flow with the pump running, it should get reasonably mixed. You can lightly brush the side and bottom of the pool when you are done if you think it doesn't circulate well enough. If you pour in front of a return that is opposite a skimmer and/or above a floor drain, then the chlorine will go back to the pump (diluted) and come back into the pool via other returns.

Denniswiseman · Postby **Denniswiseman** » Mon 05 Mar, 2012 05:26

Hi

I'm using Sodium Hypochlorite 14-15% so I expect it will be a lot higher. I don't have a lot of top up water so it must be the chlorine raising it

I won't pour into the skimmer then otherwise all seems OK