Using Muriatic Acid
Posted 13 November 2007 - 01:31 PM
Posted 13 November 2007 - 06:45 PM
When you add acid, you should have the circulation pumps running and should VERY slowly add the acid over a return jet so that it mixes thoroughly. For extra safety, I would take a bucket and fill it with spa water and add the acid to the water in the bucket first (you always add acid to water to prevent splashing -- never add water to concentrated acid), stirring it (not with your hand, obviously, but with a stirrer) and then slowly add the bucket of acidified water to the spa over a return jet.
If you have been running your jets during the 4 hours before you remeasured, then the pH will go back up from the outgassing of carbon dioxide.
The procedure to lower the TA is shown in this post. If you do get your TA lowered, then you should find less of a tendency for the pH to rise. By the way, what source of disinfectant are you using? Did you start out with Dichlor and are now using unscented bleach? Usually while one uses Dichlor and, to a lesser extent, MPS non-chlorine shock, the pH won't rise as quickly as these are both acidic (the Dichlor is acidic when accounting for the usage of chlorine which is an acidic process).
Dry acid (sodium bisulfate) is easier to use in a spa, but so long as you are careful in adding the Muriatic Acid, it is OK to use. I assume you are using a good test kit for your measurements such as the Taylor K-2006 or the tftestkits.com TF100 (these are test kits for chlorine, not bromine, though the TF100 has an OTO test that can be used for both).
By the way, you do NOT add baking soda to lower the TA to 50 -- Baking Soda raises the TA level. To lower the TA, you use a combination of aeration and acid addition done at low pH as described in the post I lined to above.
Posted 13 November 2007 - 08:26 PM
I am trying to follow the steps outlined in the post you referred me to, thats what started this whole operation. I understand that Baking Soda will increase the Alk. When I mentioned it above I was thinking that the Acid would lower the Alk. below the 50 mark by the time the pH got to where I wanted it to be.
Since adding more Acid will be OK, I will retest in the am and then add more Acid 1/4 oz. at a time until I get the pH down to 7.0 then Aerate until pH goes up to 7.2 then Acid back down to 7.0 and continue doing this until the TA is at 50. Is that about right?
Posted 14 November 2007 - 12:09 PM
Posted 14 November 2007 - 01:26 PM
Total Dissolved Solids 1000
Free Chlor 0
They suggest adding 3/4 cup Alkalinity increaser and 1 tbsp chlor. con. and then bring a sample in on friday to be re-tested. Can I use 3/4 cup of Baking Soda? and Should I use MPS to start to bring up the CYA and aeration to bring up pH? Any help would be most appreciated as my grandson is comming on Saturday and I know he will want to use the spa and I don't want to send him back with a rash.
Posted 14 November 2007 - 03:17 PM
I'd be more concerned with the lack of disinfection over a long period of time since using only MPS non-chlorine shock is the wrong advice. You have to use some sort of sanitizer to kill bacteria. MPS alone will not do that. So assuming your chlorine test is decent, add some Dichlor to the spa assuming you've never added any since your last refill so that your CYA level is truly zero. The Dichlor will add both chlorine and CYA to the water. I would just add one ounce weight of Dichlor which is roughly one fluid ounce (2 tablespoons or 6 teaspoons). Each subsequent day, add 3 fluid ounces (6 tablespoons) of unscented bleach (don't add Dichlor again until after your next drain/refill of the tub).
The tub should be safe by the weekend if you use chlorine every day as prescribed. Who knows what the real pH is, but even if it's 8.0 that's not a terrible problem. The pH most likely will not climb that much above 8.2 to 8.4 anyway -- though it would be better to get the pH lower, I don't trust your pH test strips.
Once you get your Taylor K-2006, you'll know what's really going on and can then report back here and we can get your tub in good shape. I suspect you'll just need a minor pH adjustment.
Posted 14 November 2007 - 04:20 PM
Posted 14 November 2007 - 06:27 PM
Posted 14 November 2007 - 08:20 PM
I wonder how many spas in my area have very high levels of CYA with out knowing it, since this pool company is only one of two in town. They gave me a brochure from Spa Essentials that said to keep my Alk. up to between 125-150 ppm. I have instructions from SunPurity Mineral Sanitizer that says to keep the Alk. to between 80-120 ppm. It can all get rather confussing. But It makes more sense to me to keep it down to around 50 if that helps stop the pH fluctuation. Do you still feel that I do not need to increase the calcium?
Posted 14 November 2007 - 08:42 PM
It's possible for the well water to have low CH, but it would be unusual. Again, I'd wait until you get your own accurate test kit before doing anything other than what I prescribed (chlorine and baking soda). It's rather easy to increase CH, but decreasing it can only be done with a partial drain/refill (assuming the fill water is low in CH).
It's really disturbing how your pH test is 8.0 and theirs is 7.0. The pH test, even with test strips, is pretty hard to get that far off.
Anyway, sit tight until you get your own test kit. Just do the chlorine regimen I described and add a little baking soda and your spa should be OK to use.
Posted 15 November 2007 - 07:53 AM
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