With CC less than 0.5 - could there still be algae?

[ned8377]

Had a pool party last Saturday with lots of people in the pool. Probably about 15 adults for a couple of hours. Then we had a very hard and long rain on Monday morning. I noticed on Tuesday that there was yellow powder on the floor which brushed up into a cloud like pollen has done in the past.

Before and after the pool party I had been maintaining 4% chlorine and CYA 30. Combined chlorine is always and still is less than 0.5 ppm. Sometimes doesn't turn back pink when adding the 5 drops of R-0003. This morning FC was 5 ppm and combined 0.5 with one drop of R-0871 turning the sample back clear. I've been running the pump 24/7 and put in some skimmer socks this morning to try to catch some of the pollen but they don't seem to be catching anything so I am wondering if I have green or mustard algae since the pool is green now and can barely see the drains 10 feet down. There was more yellow stuff on the floor this morning that could be brushed up.

Tonight I'm going to do an OCLT and find out for sure but always thought that if I had algae CC would be higher. Or should I start the SLAM tonight? Any thoughts on the CC question? Thanks!

 

[duraleigh]

It's likely you have mustard algae. It's a little bit tougher to get rid of but no really big deal.....continuous elevated chlorine is the answer.

I suggest you read "The ABC's of Pool Water Chemistry" up in Pool School. Follow that with the SLAM article and follow that with the Mustard algae article.

Don't worry about your CC results at that level......they will fluctuate even during normal operation. If your CC's were up around 1.5 or greater, that is a cause for concern (they actually can temporarily get that high or more during a SLAM )

 

[woodyp]

I know......."a guy",,,,,,,,here who once had algae and never any CC. "HE" usually has some after a pool party though.

 

[pooldv]

LOL, I know a guy too that has had algae and no CCs after letting FC drop to 1.5ppm for a little too long water also remained crystal clear.

 

[Catanzaro]

Had a pool party last Saturday with lots of people in the pool. Probably about 15 adults for a couple of hours. Then we had a very hard and long rain on Monday morning. I noticed on Tuesday that there was yellow powder on the floor which brushed up into a cloud like pollen has done in the past. Tonight I'm going to do an OCLT and find out for sure but always thought that if I had algae CC would be higher. Or should I start the SLAM tonight? Any thoughts on the CC question? Thanks!

I would perform an overnight test to determine your total loss. Anytime I have this type of activity in my pool (and if you had lotions, oils, hairspray, deodorant, etc.), this contributed to the total consumption for the day. I have ran tests and determined that any type of activity like this usually yields about a 4.5 ppm loss per day (of course this could be way off), but at least I have a guide. So in the morning, I add enough liquid chlorine to increase by this amount, after testing with the TF-100. Then I test at night and if the CC has increased, I add a little more chlorine and sometimes will run the filter all night long, then test again in the morning. Usually, I am clear. If there was an issue, at least I could SLAM the pool immediately and chances are that this would clear up within a day or so. I would rather be safe then sorry.

I noticed your pool is 45,000 gallons. That is quite a large pool. If brushing is not done frequently and circulation/time of pump running is not sufficient, you could have had "non visible" algae and the party is what "broke the camels back".

How many skimmers, main drains, and returns do you have in the pool? I have the "octal system", which increases PH, but the water moves quickly, helping circulation tremendously. This may be something to look into, and I am very happy with them. These also quickly help mix the liquid chlorine every morning.

Amazon.com: Circulator 10022a Automatic 360 Rotating Swimming Pool Cleaner Jet with Water Control Bottom Cap: Patio, Lawn Garden

The Circulator Rotating Water Jets for Swimming Pools - YouTube