Natural Chemistry | PhosFree Extra Strength

Natural Chemistry PhosFree Extra Strength is a concentrated phosphate remover — the fix for water where phosphates have climbed high enough to feed algae, burn through sanitizer, and choke the output of Onzen and Spa Boy salt cells.

Why phosphates matter: they enter with fill water, body products and debris, and they're pure fuel for everything you don't want growing in a spa. If your sanitizer vanishes faster than it should — or your salt system can't hold a reading — test phosphates before blaming the equipment.

Spa dosing — small amounts: the bottle's rates are written for pools, so spa doses are tiny. At the heavy-treatment rate (1 L per 38,000 L), a typical 1,500 L hot tub needs only about 40 mL. Clean the filter first, add the dose with the pump running, circulate for 48 hours, clean the filter again, then retest. Repeat until phosphates read below 100 ppb.

Quick tips:

• Test first with the AquaChek phosphate strip — treat what you measure, not what you guess
• Treat algae before treating phosphates, with chlorine under 5 ppm
• For routine maintenance levels, No-Phos is the everyday-strength option