Borates Calculator
Calculate boric acid or borax dosing to add borates (30-50 ppm) to your pool or hot tub.
BORATE CALC
Borates Adjustment
0 if you've never added borates
Recommended: 30-50 ppm (50 is most common)
Boric Acid Dosage (easiest — no pH impact)
Boric Acid
-- oz
Also equals
-- lbs
Will raise borate to
-- ppm
Buy Boric Acid on Amazon
Alternate: 20 Mule Team Borax + Muriatic Acid
20 Mule Team Borax
-- oz
Also equals
-- lbs
Muriatic Acid (31.45%)
--
Required to offset pH rise
Borax raises pH ~1.0
Buy 20 Mule Team Borax on Amazon
How to Add Borates:
- Test pH and TA first — both should be in range before starting
- With pump running, broadcast boric acid (or borax) slowly across the water
- If using borax, add muriatic acid 30 min later in deep end with pump on
- Brush walls and floor to help dissolve any residue
- Wait 24 hours before testing borate (use a borate test strip)
Why Add Borates?
Borates at 30-50 ppm act as a secondary pH buffer (in addition to alkalinity), suppress algae growth, reduce chlorine demand, and make the water feel softer and silkier — especially noticeable in hot tubs.
Target Borate Levels
| Use Case | Target Borate |
|---|---|
| Hot Tub / Spa | 30-50 ppm |
| Pool (general) | 30-50 ppm |
| Pool (algae prone) | 50 ppm |
| Maximum safe | 80 ppm |
Pet Safety:
Borates above 50 ppm can be harmful to dogs that drink pool/spa water. If your pets drink from the pool, keep borate levels at or below 50 ppm and discourage drinking.
Borates above 50 ppm can be harmful to dogs that drink pool/spa water. If your pets drink from the pool, keep borate levels at or below 50 ppm and discourage drinking.
Boric Acid vs. Borax — Which to Use?
Boric Acid (recommended for hot tubs)
- Pros: No pH change — just add and you're done
- Pros: Easier to dose precisely in small spa volumes
- Cons: Slightly more expensive per pound
20 Mule Team Borax + Muriatic Acid
- Pros: Cheap and available at any grocery store (laundry aisle)
- Cons: Raises pH ~1.0 — must add muriatic acid to compensate
- Cons: Two-step process requires pH retesting
For hot tubs: Stick with boric acid. The volumes are small enough that a single
small bag lasts a long time, and you avoid handling muriatic acid in tight spaces.
For educational purposes only — full disclaimer ↓