Why Convert to a Borate Hot Tub?
Converting your hot tub to a borate spa (aiming for ~50 ppm borates) is one of the best upgrades you can make for water quality and ease of maintenance.
1. pH Buffering (Made Simple)
Think of pH as a volatile seesaw—hot tub aeration from jets and bather use naturally forces pH to constantly drift upward. “Buffering” simply means adding a chemical lock or safety net to that seesaw. Borates anchor the pH around the ideal 7.4–7.8 zone, preventing sudden spikes or drops.
2. Silky-Soft Water
Borates alter the surface tension and mineral feel of the water. Instead of harsh, drying chemical water that leaves your skin feeling tight, borate-treated water feels silky smooth, luxurious, and noticeably softer on your skin and eyes.
3. How It Saves You Money in the Long Run
Fewer Chemicals: Because borates lock your pH in place, you’ll stop burning through bottles of pH Down or Acid to fix pH drift.
Longer Sanitizer Life: Chlorine is most effective when pH is balanced. Stable pH allows your chlorine to sanitize efficiently without getting consumed as fast.
One-Time Treatment: Borates do not evaporate! Once added, they stay in the water until you perform a complete drain and refill.
Supply Run: The Lowe’s Trip & Dosing Adjustments
To start the conversion, I headed to Lowe’s for the core ingredients: 20 Mule Team Borax and Muriatic Acid.
Borax Deal: Borax is normally listed with a discount for Lowe’s members (check your local store tags or app discounts to grab the savings!).
Pay Attention to Muriatic Acid Concentration! Lowe’s only had Klean-Strip GREEN Muriatic Acid in stock. This product is a lower-concentration (~15%), low-fume formula rather than standard 31.45% pool acid.
Important Dosing Tip: Because this formula is half-strength, I had to double my acid dosage to balance out the high pH spike of the Borax. Always check your bottle’s acid percentage before measuring!
The Step-by-Step Conversion Process
I measured out my chemicals using a digital food scale for the Borax (by weight) and a clear liquid measuring cup for the acid to keep accuracy as tight as possible.
Pre-Conversion Water Check: Using the HTH Test Kit (online version): Cheaper at Lowes.
Before adding anything, I verified my baseline parameters:
Total Alkalinity: Balanced
pH: ~7.4–7.6
Sanitizer (Chlorine): On point
Dosing in Two Halves
Because adding Borax causes a massive pH spike, you must add it in two split doses along with the neutralizing acid.
Dose 1: Pre-dissolved 11 oz of Borax in a bucket of warm spa water and poured it in. Followed immediately with 11 fl oz of pre-diluted Green Muriatic Acid. Ran the high-speed jets with the cover off.
The Foam Phenomenon (Don’t Panic!): About 5–10 minutes into the first dose, a thick layer of foam built up on top of the water. This is completely normal! The low-fume “Green” acid contains mild additives/surfactants, and aerating dissolved borate solids momentarily changes water surface tension. Once the chemicals fully react and mix, the suds break down naturally.
Dose 2: After letting the first round circulate for 15 minutes, I repeated the process with the remaining 11 oz of Borax and 11 fl oz of Green Muriatic Acid.
Final Circulation: Let the jets run for another 20–25 minutes to blend everything thoroughly.
Final Results & Testing
After letting the water circulate, I checked the pH level with my 6-way test kit. The pH landed right in the sweet spot around 7.5–7.6!
What about Borate Test Strips?
I opted to skip buying special borate test strips to save a few bucks on this trip. By calculating the exact gallon volume of my tub (450 gallons) and following the standard dosage ratio, I can trust the math gets us right to ~50 ppm. If I notice any pH instability down the line, I can pick up a pack of strips to double-check.
Final Thoughts
Try it Out! If you like the results, Wait to check out my pool conversion results blog. (coming soon) This entire project took virtually no manual labor—just a quick supply run and letting the hot tub jets do the work. The water feels incredible, and my pH is locked in!