More than likely it is algae and will require a TFP "SLAM". Can you post some test results from a TF-100 or Taylor K2006? That would be ideal.
SLAM is the term used when we “Shock” our pool to a higher “Level” of Free Chlorine (FC) and “Maintain” it that way until 3 objectives are met:
1. Water is clear
2. You do not lose any more than 1ppm of FC overnight (that's the OCLT)
3. CC (Combined Chlorine) is <.5
** You MUST meet ALL 3 items above to properly do a SLAM. Simply “spiking" the FC higher than normal isn't SLAMming, therefore there’s a good chance your algae will return.
To prepare for a SLAM, you should do the following:
- Adjust PH to 7.2 - 7.5; don’t worry about it after that during the SLAM
- Ideal CYA should be 30; the higher the CYA, the more bleach required
- Have a good amount of “regular” liquid bleach on-hand to keep your FC high at all times
Use the Chlorine/CYA chart (link in my sig) to bring your FC up to the proper SLAM level rating based on your current CYA and make sure it stays there (MAINTAIN) until you meet ALL 3 criteria listed above! That may take just a few days or even a week or two! That is absolutely critical for success.
At the same time, continue to run your pump 24/7. Remove any “muck” and debris, scrub all parts of your pool to expose any algae, and vacuum/clean (or backwash) filter as necessary. You may have to do this several times. It's a lot of babysitting, but with patience and consistency, you will succeed.
- - - Updated - - -
- Even with my cut & pasting, Patrick beat me to it.
