Biguanide is polyhexamethylene biguanide or shortened as PHMB. Two popular brands of biguanide for spas are Soft-Swim & Baquacil. These generally contain 20% PHMB. These products are EPA approved for use in spas, however unlike the halogen-based sanitizers (chlorine & bromine) they are not also oxidizers.
Biguanides attached to single cell organisms, notably bacteria, causing the cell wall to break. Essentially, the bacteria start leaking and die.
Benefits of Using Biguanides:
So what exactly do biguanides bring to the table, or pool rather, that chlorine doesn’t? For one- money. Using a biguanide, like Baquacil, is rather expensive. Generally speaking, pool maintenance isn’t cheap but in comparison to chlorine, even biguanides are pricey. As mentioned before, if you choose the biguanide route, you also have to purchase additional oxidizers. That means more money out of your pocket. One of the true benefits is that, unlike chlorine, it does not break down in high temperatures. Additionally, biguanides do not have a lingering smell and does not erode bathing suits and vinyl liners.
The Downfall of Biguanides
In addition to cost, biguanides also have a tendency to cloud and/or cause foaming. Typically, pool owners aren’t using enough oxidizers to rid the slime and mold problem that’s a by-product of the system. One of the biggest issues with using biguanides is its resistance to microorganisms in the water. Over time, some microorganisms become biguanide-resistant. Usually, shocking your pool is the only way to rid your pool of these microorganisms. However, shocking your pool also destroys all of the biguanide in your water. It’s definitely a lose-lose situation.
Converting Biguanide (BioGuard Soft-Swim or Baquacil) to Chlorine
Using BioGuard Oxysheen®
1. With the filter running, adjust the pH into a range of 6.8-7.0 ppm. Isolate the heater from the rest of the circulation system. (NOTE: You must be able to isolate the heater to drop the pH this low). If you cannot isolate the heater, you can keep pH at 7.2. You will just need to repeat step 3 more times with the slightly higher pH.
2. Apply 12 lbs. of Oxysheen® per 25,000 gallons with the pump running. Circulate 48 hours. The water may turn green and cloudy.
3. Test the biguanide level. If any residual remains, apply 3 lbs. of Oxysheen® per 10,000 gallons and circulate 48 hours, then retest.
4. When no biguanide residual is shown on the test, remove a bucket of water from the pool and sprinkle a small amount of Super Shock or Liquid Chlorine into the bucket. If water discolors or clouds, repeat step 3 until no reaction occurs in the bucket test.
5. When you have confirmed no reaction occurs, perform a complete water analysis and balance according to the ALEX® Pro recommendations for your new sanitizer type.
6. Backwash the filter and use Jack Magic Power Blue Cartridge or DE Filter Cleaner according to label instructions. For Sand Filter, the sand in the tank must be replaced with new sand.
NOTE: Shocking the pool each day with Burn Out® or Super Shock for approximately one week may be necessary to eliminate all chlorine demand and clear the water. If you would like faster results to clear the water, BioGuard Pool 911 would be recommended to clear and clean up the waters appearance.