Cloudy water

[gbowen1]

OK this is a first for me in 10 years of hot tub ownership. Changed the water for winter, put in a clean filter.  Put in metal remover.  Spent a few days adjusting calcium hardness and total alkalinity.  Got hardness, TA, and pH perfect (it was at 7.4).  Added chlorine before going away for the weekend.  My son went to use the tub the next day and the water was cloudy.  I checked and rechecked hardness, TA, and pH and all are fine.  I also used non chlorine shock and still cloudy.  For some reason when I check free chlorine level there is ZERO.  I add dichlor chlorine to get the level to or just above 5 PPM (too high) and leave overnight.  The next day, still cloudy, all levels are fine except again no chlorine (no color change).  Where is the chlorine going??  I think there may be bacteria in the water, but why is the chlorine not taking care of this problem?  Added more tonight and still cloudy.

[chem geek]

You need to shock with a lot of chlorine and keep adding it until it holds.  If that is not successful, then you will need to do a decontamination procedure.  Apparently, the chlorine level dropped to zero and was that way long enough for bacteria to grow and form biofilms.

[bob snader]

The cloudy water is the chlorine zeroing out before it can completely oxidize all the waste. Once it becomes cloudy then as the above mentions you have to shock it to get it back to normal. It usually takes about 2 or 3 days.

The speed at which the chlorine is used up is relative to the amount of waste it must oxidize. If you have an increase in the number of bathers for example, or bathers who don't shower before entering the waste level will increase and as a result so will the consumption of chlorine.