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Thread: Possible Mustard Alge?

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    weatherillgrp's Avatar
    Join Date
    May 2014
    Cortez, CO

    Possible Mustard Alge?

    The PH, TA, CL in my pool are all within desirable levels. Since I have a outside pool with a power vinyl cover I keep the CYA at less than 20. Because of the cover I keep the TC between 1 and 2. I don't know for sure how much below 20 it is but when I do the test for CYA I can still see an obscured black dot when the tube is full of solution. 5 days ago I noticed a green/yellow stringy stuff in the water. The water is very clear. I presume it might be mustard algae. Therefore I decided to slam the pool. I used the CYA Chart for slamming with a CYA level of 20. It requires that I maintain the slam level at 10. The first night I preformed the overnight FC test. The TC the next morning was 5. I slammed the pool again back to 10. The next morning it was at 5 again. Again I brought the TC back to 10 and the next morning it was back to 5. I measured the CC also that morning and it was 0. Out of frustration and because of my schedule I was not able to slam it again yesterday. This morning the FC was 1. I added enough bleach to bring it back up to 10 and am again trying to get it to take care of whatever is in the pool. All during this time the water has remained clear, the CC is at 0. I have checked it every 4 hours today. At 12;30pm it was down to 7.5. Added bleach to bring it back up to 10. Checked at 4:30 pm - 8.5, added bleach, checked at 7:50-9.0 added bleach. Will now check for loss this night and retest in morning. There was a small amount of the green/yellow stuff on the floor but was not sticking. So I got 2 out of three correct but can not get the FC to not drop more than 1 overnight. Could it be I need to increase the CYA even though I keep the pool coved when not used and always add Bleach after each use. Any suggestions?
    18K gal, IG vinyl, 1 hp single phase Pentair Pinnacle pump part 7-177474-01, Star-Rite Cristal Flow Filter model T-240BP-1, 266,000 BTU Raypac gas heater model PR266AENC, Coverstar electric safety cover, Hayward Navigator Pool Vac, Pentair model 300 Auto Chlorine Feeder( not using). TF-100 Test Kit. Built June 2007

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    Butterfly's Avatar
    Join Date
    May 2007
    South Carolina

    Re: Possible Mustard Alge?

    Well, I suggest you increase CYA to about 30, which will give you something you can measure and confirm. Also, pools do need to breath/outgas so you could open it up several times a week.

    Continue to SLAM. When you pass the three criteria, I would finish with a Mustard Algae SLAM Don't forget all those nooks and crannies!
    TFP Moderator TF100 Test Kit TF100 TestKit YouTube Channel PoolMath
    You're done SLAMing when:
    1)You lose 1ppm or less FC overnight, & 2)You have .5ppm CC's or less, & 3)your water is clear.

    ~ One should not use a sledge hammer to swat a mosquito. ~

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