Originally developed as a pre-surgery anti-microbial scrub, PHMB was patented in 1977, and marketed for pools and spas under the trade name Baquacil. This technology has the distinction and the EPA approval as the only non-halogen sanitizer available for pools and spas. Biguanides, as the class of chemicals is called, is a hydrogen peroxide-polyhexamethylene chemical. You may have heard of using peroxide to bleach your hair or for an ear infection. The formulation is a bit different, but basically in the same chemical family.
When the patent expired back in the 90’s, Bio Lab introduced a line of biguanide products under the name Soft Swim. A full system for complete halogen free water care, these products are also a stand alone alternative to traditional sanitation methods [chlorine]. The Biguanide itself is combined with algaecides and hydrogen peroxide for periodic oxidation. The system tends to gum up filters, and of course a product is available to de-gum it. Biguanide are not recommended for spas or aerated pools. As long as you don’t add any other chemicals but those recommended by the manufacturer, you’ll do fine; but add a small amount of chlorine and your pool looks like orange sherbet! Biguanides are also incompatible with TSP, ozone, detergents, ionizers, and other common chemicals, but are not at odds with any water balancing chemicals you may add to adjust pH, Alkalinity or Calcium.
Biguanides have been reported by users to be easier to use, with less chemical level testing, and less adding of chemicals. The water doesn’t smell of chlorine of course, and the reduced surface tension gives the pool water a smoother feel. Biguanides don’t degrade with sunlight, temperature, or changes in pH levels like chlorine. At recommended concentrations, biguanides won’t irritate the skin or eyes and can’t corrode pool equipment. And, no, at recommended levels, using hydrogen peroxide will not turn your hair platinum blonde!