Scottie_In_IA_1981 Posted April 20 Report Share Posted April 20 I plan to use boric acid on my next spa refill. It is a plaster/tile spa that I estimate to be between 300 and 350 gallons. The figure I found says to add .0457 pounds per 10 ppm per 100 gallons. So, for 350 gallons I would need about .8 pounds to achieve 50 ppm. The recommended 'range' I believe is 30-50 ppm...so, if my spa is 'between 300 and 350 gallon', adding 2/3 of a pound (302.4 grams) would still land me at the 40-50 ppm range. Is my math correct here? I found a 340 gram package of pure 'cosmetic grade' boric acid on ebay...which sounds like a pretty ideal size. Does this sound like an acceptable source of boric acid? Also, am I correct that it only needs to be added once, even if I keep the spa water for 4-6 months? If it dissipates to a small extent, and/or if I lose some water to splash out...I figured I could use 300 grams upon refill and then maybe add the remaining 40 grams from the package after a few months. One last question that I have is how/when to add the boric acid after refilling the spa. I have a pretty high TA and it takes me that first day or so of gradually adding acid and aerating to get the PH to stabilize. I also add calcium since I have a plaster/tile spa and the well water runs through a water softener. So, can I add the boric acid AFTER I've finished adding all of the acid and the calcium?...or, would it be better to add at a different stage? And, am I right to guess that I can go ahead and just add all 300 grams of the boric acid at once, and that it won't have any drastic immediate effects on the PH or TA? Quote Link to comment Share on other sites More sharing options...
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