Cloudy Pool

  • Last Post 21 August 2020
RJD422 posted this 12 August 2020

Hi, after heavy rains from the hurricane last Tuesday my crystal clear pool is cloudy - Immediately after the storm I fished out several branches, lowered the overall water level back to mid skimmer, vacuumed and cleaned out the filter basket. My chemistry post hurricane is pretty good - last Friday free & total chlorine 2.82 ppm, combined - 0, pH 7.4, hardness 91, alkalinity 82 and Cy Acid 100, phosphates 723 ppb, copper & iron both 0. Late last week I was getting green algae staining along the walls and deep end floor which seemed odd as the pool was properly chlorinated. It did easily brush away but had been coming back quickly. I'm not seeing it in the last two days. I had the water tested again Monday and gave the filter cartridges a good hosing off this morning. Monday numbers - Free & Total Chlorine 4.96, combined - 0, pH 7.3, hardness 90, alkalinity 75, Cy Acid 102, phosphates 698 ppb, copper & iron both 0. I raised the alkalinity Monday and also used a clarifier (which in hindsight I should've done after hosing off the filter cartridges, not before). Today the pool is cloudier than the previous days, even now 5 hours after cleaning the filter cartridges. Any thoughts?? Thanks. 

InyoRob posted this 21 August 2020

The one thing that jumps out to me is the high CYA level. High CYA can impact the ability of the free chlorine to sanitize the pool. At 100ppm CYA, you need a free chlorine level of 7.5 to prevent algae. My suggestion would be to drain some water from the pool and fill it up with fresh water. Then shock the pool and get the free chlorine level up around 10ppm. This should kill all the remaining algae. 

The water will turn a cloudy white when the algae is dead. Then you need to keep the pump running until it clears up. Cleaning the filter multiple times a day will help speed up the process.