Hi Guys. I've only had a tub for 5 months and I've been having a problem with the whole chemistry thing.
The initial filling water is very alkaline so I threw in some Dry Acid to bring it down. I have then been using Stabilised 20g Chlorine Tablets (1 Tablet/day) and I've seen the Ph drop drastically until we were all itching like crazy. I then poured in some proprietory Sodium Carbonate to increase the Ph. Eventually I dumped that water and the second filling I've simply put in the regulation 1 tablet/day. The Ph is now very low (30 days after filling) and I'm putting in Na2CO3. I have found out that the tablets have Trichloroisocyanuric Acid as their active ingredient so I guess it would acidify the water. One thing I have noticed is that the test strips do not reflect any Chlorine content - it looks as if I'm not using any Cl at all but the water is beautifully clean.
I'm a bit worried that I'm using the wrong product or are spas simply a bast**d to keep neutral?