Green pool and no CC??!! What gives?

JFB

0
LifeTime Supporter
May 13, 2013
98
Monréal, Québec, Canada
Today I went to the pool to take some measurements for the winter cover. The solar cover has been on pretty much permanently for 3-4 weeks. I lift it to take a look and lo! and behold, GREEEEEEEEEN! Well, you know what you get after a summer of being cocky to yourself about great test results? A green pool towards the end of the season. It's getting cold here, and so swimming is pretty much over, but the pool isn't closed.

So first thing I did was test FC and CC. FC was at 6.0 and CC 0.5. 0.5??!! That makes no sense to me. After reading everything in pool school more than once, if anything I was fully expecting some CC!!! Nonetheless, I began to SLAM. I did not do a full test, as I have been testing all summer and my results have been pretty consistent. I will definitely do a full set of tests tomorrow... I started at 1400 today and maintained FC to 16 by testing about every hour or so. My CYA has been rock solid at 50, slowly dropping to 40 last time I tested it, about a month ago. TA has always been 60 and CH 100.

So. What happened? I'm trying to figure it out so I don't repeat the same mistake later. Did I leave the solar cover on too long? Was it the Borax I added about a month ago to bring the pH from 7.2 to 7.6? Or was it the fact that a couple days ago I noticed on my P4 panel, the "check system" light was ON. I'm not sure how long it had been ON, but I reset the system and it started to chlorinate. The light hasn't come back ON. But would my FC be at 6.0 3 days later? Was it not chlorinating for however how long the check system light was ON?

As it stands now, I brushed and brushed, and the pool is uber-cloudy. But I just tested and my FC was 20 (was targeting 16 but I also started the superchlorinate to help keep FC levels up throughout the night) and the CC was still 0.5! My pH is at 8.2, could that be a side effect of too high FC? Should I worry about pH later, once the water is clear and I pass OCLT?

I should've known better than be proud of my clean pool this summer... Something was lurking to come and get me.

Please advise!

JF
 
For some reason the SWG stopped making chlorine and your FC levels dropped, thus the green water.

Your PH will read a false high with FC levels of 10 or higher.

SLAM until you pass
1 water is crystal clear
2 CC of 0.5 or less
3 pass the OCLT
 
So first thing I did was test FC and CC. FC was at 6.0 and CC 0.5. 0.5??!! That makes no sense to me.
For some reason, a common misconception has developed that a pool with algae HAS to have excessive cc's. Not so.

CC's are a good indicator of the presence of algae but they do NOT have to be there for algae to exist as you have discovered.
 
Well, I tested this morning at 9am. The FC levels held. FC was 20.5. I'm glad to see the superchlorinate is able to hold the chlorine level throughout the night. Helps with the SLAM process... The water is blue now, and most of the green from the bottom is gone. I'm thinking with some brushing and vacuuming today it should look good tomorrow... Let's cross our fingers!
 
Last night at 8pm FC was 25.5 (a little high, but I guess that's the SLAM process working for me). This morning at 9am, measured FC at 24.5 after the sun had been out for about an hour or so (I was up all night with 2 young kids crying, sue me for sleeping in :mrgreen: ). CC is less than 0.5. And I think the pool is clear. I can see the bottom, it's not cloudy, but at night, when I turn on the lights in the pool, I can see zillions of little white specs floating around in the water... Is that the leftover from the breakdown that will be filtered out in the next week or so? That's the only thing I'm not sure about. For the rest, I think the SLAM process is done!

This was my first time, followed pool school to the letter, and it took 3 days. I can't imagine how much money I would've spent at the pool store if this site wasn't here to help me. This time it cost me a little extra electricity (pump and SWG 24/7 for 3 days) and 1 jug of 10.3% chlorine (5$). Pretty cheap fix!

Thanks TFP! :goodjob:
 
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