Roxymonkey Posted March 25, 2014 Report Share Posted March 25, 2014 Hi all, This is my second fill of this spa since buying it last November. 2 weeks ago I emptied it and filled it straight away with mains tap water. My supply is 7.6 ph and 150 - 200mg/l TA. (Confirmed by my test and water supplier). Once full, I tested the water and both readings were at the top of the scale on my palintest comparator. I added arctic pure adjust down as instructed 50 g at a time. After about 650g (22 ounces) of dry acid later, I now have a TA of 100 and PH of 8.0. I have been told by my spa dealer and Arctic tech guys that this is very unusual and they have no idea why I had to add so much acid. Any ideas anyone as to why I have used so much acid when my water supply is ideal ? Spa - Coyote Maricopa by Arctic Size - 1500 litres / 350 Gallons Many thanks, Paul Quote Link to comment Share on other sites More sharing options...
chem geek Posted March 26, 2014 Report Share Posted March 26, 2014 Your high TA level in the fill water is the reason you need to add so much acid. TA is a measure of the over-carbonation of the water and over-carbonated water outgases carbon dioxide which causes the pH to rise. By the way, 350 gallons is 1325 liters, not 1500. Adding 50 grams of sodium bisulfate to 350 gallons (1325 liters) of water lowers the TA by about 15 ppm. 650 grams would lower the TA by 191 ppm which is too much given your TA starting point. I certainly hope you did not damage your spa with the pH getting lowered too much. How are you measuring your TA and pH? If by test strips, they are often not accurate. You should have a Taylor K-2006 test kit for accuracy. Your water supply is anything but ideal. The TA is very high. You should also check your CH since that is often high as well when the TA is high. Quote Link to comment Share on other sites More sharing options...
Roxymonkey Posted March 26, 2014 Author Report Share Posted March 26, 2014 Hi chem geek, Many thanks for your reply. I am using a palintest comparator with rapid dissolve tablets. Unfortunately I couldn't find the Taylor kit in the UK. Re: Gallons; I should have made it clear, U.S. Gallons are different I believe. 350 Gallons (UK) equate to about 1591 litres. The acid was put into the spa each day 50g at a time and then the next day tested again. For the first 450g there was no change on my test results, it was still at the maximum. (Comparator goes up to 8.2ph and 250 TA mg/l) If my tap water has a TA of 200 max, why did it shoot to double or more when it entered the spa? Quote Link to comment Share on other sites More sharing options...
chem geek Posted March 26, 2014 Report Share Posted March 26, 2014 Ah yes, UK gallons. Sorry for my forgetting about that. So apparently your TA was quite a bit higher than 250 ppm. I didn't realize the test kit had a limit. You reported that your tap water had 150-200 ppm but apparently your TA was over 200 ppm. I don't think the TA went up when going into the spa. 650 grams of dry acid in 350 U.K. gallons (1591 liters) would lower the TA by 159 ppm so if you ended up at 100 ppm TA then that means you started with around 260 ppm TA so that's not double or more compared to 200 ppm TA from the tap. It's possible that the acid isn't as strong as normal dry acid that is 93.2% sodium bisulfate. Quote Link to comment Share on other sites More sharing options...
Roxymonkey Posted March 26, 2014 Author Report Share Posted March 26, 2014 Ok, that makes more sense than the many websites out there to confuse with different theories! I am using the arctic pure range adjust down which says sodium bisulphate on the bottle but doesn't give the strength. Would it be "normal" to have to add this amount of acid to a fresh fill then? Quote Link to comment Share on other sites More sharing options...
chem geek Posted March 28, 2014 Report Share Posted March 28, 2014 In your case, yes. Because your TA is starting out so high. Quote Link to comment Share on other sites More sharing options...
RelaxedinMissouri Posted April 3, 2014 Report Share Posted April 3, 2014 Roxy, Our TA is *always* that high at a fresh fill. And every time it takes 26 oz. muratic acid (added incrementally) to bring the TA to 100. Then, after a bit of tweaking (usually another 2 oz. of dry acid) we land on our happy 60 TA or so. Whereby it stays prettymuch rock steady until the next fill in 3 months. This keeps our PH in the 7.6- 7.8 range. Our tub is 419 gallons. I don't speak Liter so I'm not sure how that computes. Quote Link to comment Share on other sites More sharing options...
Roxymonkey Posted April 3, 2014 Author Report Share Posted April 3, 2014 Hi Missouri, thanks for the reply. My water supplier confirmed with me that the fill water should not be that high. I have just cleaned the spa with swirl away and done a new fill. This time the Alk was 150 straight away and the ph was 7.6. After a much less amount of acid the water is now spot on. Conclusion: no idea what made my last fill water go crazy in comparison other than something bad was living in my tub! If in doubt - refill. Thanks for your posts guys. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.