is this Algae? Something else?

[jgofnj]

Hi all,

Been doing well with this methods for 3 years, never had any major issues, this year has been very good, water looks crystal clear. two weeks ago, I notice this small thin little patch of green layer in the deep end/corner of the pool. Came off real easy with the brush. Now two weeks later, it appeared in the same spot again. I don't think it can be algae based on my numbers posted below but maybe it is. Should I be concerned? I am in New Jersey and will be closing the pool in two weeks.

Picture below

View attachment 33191

FC-7.5
CC-0.0
TC-7.5
PH-7.5
TA-95
CH-220 (vinyl liner)
CYA - 70

I know the CYA is a little high but the FC is 7.5 which is within the Minimum/Target range.

 

[pooladdict]

I believe that is algae, possible you don't have proper flow in that area?

 

[BoDarville]

It's hard to say. It looks like it could be algae or it could be a pollen deposit of some sort. I get these occasional pollen streaks that are from some type of plant, although it is more common in the spring than now. They look very similar to algae but they disappear in a day or so. I would try the Overnight FC Loss Test to be sure. If you pass this test, then odds are what you are seeing is something other than algae. OTOH, if you fail this test (e.g., chlorine drops by more than 1 ppm overnight,) then you have algae or some other type of organic contamination. If that's the case, I would SLAM to get rid of it before closing the pool for the winter.

 

[jgofnj]

Thanks all. I will perform the OCLT

 

[Kiss4aFrog]

Good idea to do the OCLT. http://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt

 

[SunnyOptimism]

Just remember that the OCLT was intended to be performed at the end of a SLAM and so you would be at shock FC levels.

If you do an OCLT at target FC levels, you should consider lowering your threshold for passing to something less than 1ppm, perhaps 0.6ppm and use the more sensitive 25mL sample so that your drops are more accurate (0.2ppm/drop)

Alternatively you could raise your FC up to shock level in the evening and then just use the standard 1.0ppm loss.


Sent from my iPhone using Tapatalk

 

[Big_kid]

I can't see your photo very well on my phone, but I get A LOT of pollen collected in my pool that often resembles algae. Sometimes it is bad enough I turn the pump off, let it all settle out of the water, then vacuum to waste. I always pass the oclt and have 0 cc, but it can get to looking bad on occasion.