I installed a HotSprings Jetsetter spa on April Fools Day for relaxing and bathing, because I can drain it to the yard rather than to our 2K gallon holding tank, just like a boat's, for black and gray water. I soon shifted to generic chemicals, rather than branded tradename compounds, to be frugal (or cheap). I maintain chemistry using Taylor Technologies' test kit and direction from their 'Pool & Spa Water Chemistry', PN #2004B.
In my career (15 years retired) I supervised and approved chemistry maintenance and evolutions for small nuclear power plants, but had no hands on involvement. In other words, I had lots of theory but no practice and a long time ago.
The buffer implicit in 'Total Alkalinity' (p13) seems to have little capacity, because I was constantly adding HCl or sodium bi-carbonate as the pH drifted up and down. I found a patent describing the boric acid + sodium carbonate system and, when I next changed the 'water', I installed the buffer. I have had to change the 'water' about every 45 days due to percipitants clouding it. Water is untreated well water through a charcoal filter column dedicated to filling the tub. Softened water is available.
I added it about three weeks ago, after adjusting 'Total Calcium' to 160 ppm indicated and 'Total Alkalinity' to 100 ppm. Bromine is close but high due to the small mass needed and I'd rather be a bit high, ~10 ppm. I use potassium monopersulfate oxidizer (and would like to find it as Oxone in cheaper quantities).
I added 400 grams total, 95.8% boric acid, and 4.2% sodium carbonate approximately (kitchen digital scale indicates in half-gram increments) and pH indicated 7.0. I adjusted using sodium carbonate from Taylor's Table D for 12 drops Base Demand in a 800 liter volume and pH is 7.5.
Now the 'introduction' of me and my spa is done.
The Taylor Demand Reagents and colorimetry is convenient but does not mention boric acid. Can someone direct me to a table or help me adjust Taylor's Table E for HCl to boric acid?
Thanks for any assistance. Doug Huffman, Washington Island, Wisconsin. (PS; yes, I plan to use the spa through the winter)