Convert from Biguanides to Chlorine



Biguanides, sold under the names of Baquacil or Soft-Swim or Aqua Silk can perform well, but some users develop severe water conditions and decide to switch back to chlorine as their main sanitizer.

Here's How to convert your pool from Baquacil back to Chlorine.

  1. Stop adding Biguanides! Allow levels to drop down very close to 0. You may want to run the filter longer each day, and add an algaecide (not Baqua-cide) when levels begin to get low. This process may take several days or weeks. Keep the water balanced, and the pool as clean as possible by brushing, skimming and vacuuming to reduce sanitizer demand.
  2. Clean the Filter. Biguanides can clog up filters, and leave chemical residue which may react with chlorine. If you have a Sand Filter, it is recommended that you change the sand in the tank. If this is not done, you must at least use a sand filter cleaning product made by your biguanide manufacturer (Baquacil, Soft Swim, etc.) The same applies to Cartridge Filters. You should replace the cartridge, or at least clean it and then soak the cartridge in cartridge filter cleaner and rinse thoroughly. If you have a D.E. filter, backwash it and open the filter tank; following printed instructions on tank. Remove filter grids, hose off thoroughly, then soak it in the DE filter cleaner. Hose again [very] thoroughly and reassemble. It is very important to remove all traces of the chemical from the filter media. The best way is to replace the media, where possible.
  3. Shock the Pool. With NON-Chlorine pool shock, also called potassium peroxymonosulfate. Add it at a rate of 5 lbs. per 10,000 gallons of pool water. So, if your pool is 22,000 gallons, you'll need about 11 lbs. Add 1/2 the shock, wait 24 - 48 hrs and then add the remaining. This step is important to oxidize remaining traces of peroxide in the water. Add the shock according to directions on package, with the filter pump running. Pool may turn cloudy for a few days if biguanide levels are not zero. Re-check and balance water chemistry. Run filter non-stop until water clears, backwashing as necessary.
  4. Slowly add Chlorine, very slowly. Place one tablet in a floater or chlorinator. If your pool doesn't react to it (by turning funny colors or going hazy) keep it in until it dissolves. Then add 2 tablets, and so on, until you are able to get chlorine readings of 1.0 ppm with your test kit. Maintain this level with tablets. Refrain from using chlorine shock products for one season, substituting non-chlorine shock, as needed to remove chloramines, or to kill algae or bacteria.

A good time to switch may be in the spring, after a winter of not adding any biguanides – but not in the heat of the summer. Another option is to drain the pool and refill with fresh water, which may be a good idea if the pool has suffered several outbreaks of bad water conditions.

No matter how you do it, make sure that you replace the filter media (sand, cartridge or DE grids). Also, dispose of any remaining biguanide products, so that they aren’t accidentally added to the pool.

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