Pool Community

Biguanides to Chlorine

Obviously, the first step is to stop adding your baqua-chemicals! Allow levels to drop down very close to 0. You may want to run filter longer, and add an algaecide (not baqua-cide) when levels begin to get low. This process may take several weeks.

  1. 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 a similar cleaning product, and rinse thoroughly. If you have a D.E. filter, backwash it and open the filter tank; following printed instructions on tank. Remove filter, hose off thoroughly, then soak it in the cleaning product mentioned above. Hose again thoroughly and reassemble.

  2. Balance the pool water chemistry. Then shock the pool with non-chlorine shock, Also called potassium peroxymonosulfate. Add it at a rate of 8 lbs. per 10,000 gallons of pool water. So, if your pool is 22,000 gallons, you'll need 17 or 18 lbs. Add 1/2  the shock, wait 24 - 48 hrs and then add the remaining.  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 24 hours a day, 7 days a week until water clears, backwashing as necessary.

  3. Finally, we begin to add chlorine, very slowly. Place one tablet in skimmer basket, floater or chlorinator. If your pool doesn't react to it (by turning funny colors) 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.


That's It! At least that's how we've done it. Let me know how it works!


A good time to switch may be in the spring, after a winter of not adding any baquacil or soft swim. I have heard reports of others who have said that they simply let their pool go very green, made sure the baquacil levels were 0 and then shocked it with chlorine. A simpler approach to be sure.