Algae Identification

dtarantino

Active member
Jul 15, 2016
34
Florida
#1
I'm trying to determine what kind (if any) algae in my pool. My water is crystal clear but I've noticed that when I brush the bottom and steps I get clouds of green dust that kick up. I also recently washed out our cartridge filter and it was greener than I've ever seen it.

I should note that I did an iron stain treatment over the winter so I had no FC but I used a Polyquat 60 through the process and a good amount of sequestering agent (and a Culator) to allow me to really bring my chlorine levels back up into check shortly after. I have been back to my regular maintenance of liquid chlorine in the pool now for about a month. At no point was my water ever green just cloudy.

Is there a good way to determine if it is algae or possibly pollen (our oaks are in full bloom here in FL)? Today I have a FC of 8.5 with a CC of 0, does that mean I don't have an issue? Or do I need to do an overnight FC test to see what really is going on?

Today's readings
FC - 8.5
CC - 0
PH - 7.5
TA - 90
CYA - 55

The pool has been shocked about twice since I have done the stain treatment. I should note that the color of my pool finish is a blue/brown so it's difficult to see if there is stuff sitting on the bottom.

Thanks
Dennis
 

Texas Splash

Mod Squad
TFP Expert
LifeTime Supporter
#2
The lines separating pollen from algae can be tricky at times. For pollen, one thing I'd definitely evaluate is what you see lying around the pool, decking, furniture, cars etc? Do you see a lot of pollen settling? If you do, you can assume a fair amount is settling on the water's surface as well. If you can collect it (on/in the water), pollen may seem to be more squishy while algae could be a bit more slimy, but that can be tough to compare. Both however can give that appearance of a green "plume or cloud" when brushed along the bottom. Algae will usually try to find a place to call home and be more stationary, while pollen should move in drifts if there is any water movement to do so. Pollen can also be a slightly different shades (green/yellow) while live algae will definitely be more green. That's what really concerns me about your filter.

To rule-out algae chemically, you could do an overnight (OCLT) test to see if there is any excessive FC loss. No CCs and clear water are good, so hopefully an OCLT will rule-out algae for you so you can focus on pollen management. Are you using a skimmer sock? That may help for pollen anyways. Also evaluate skimmer suction and water surface movement to that skimmer as sometime the daily wind direction can work against us and push surface debris away from the skimmer to the point it sinks. Hope that helps.
 

dtarantino

Active member
Jul 15, 2016
34
Florida
#3
Thanks. It failed the OCLT (1.5ppm) so I guess I do have algae and time to SLAM the pool. Is there any definitive way to determine if it's mustard algae or some other form? I'm wanting to know just from the standpoint of what level to maintain my PPM for the SLAM process.

Thanks
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
3,959
CT
#4
Thanks. It failed the OCLT (1.5ppm) so I guess I do have algae and time to SLAM the pool. Is there any definitive way to determine if it's mustard algae or some other form? I'm wanting to know just from the standpoint of what level to maintain my PPM for the SLAM process.

Thanks
FC level for the SLAM is always 40% of your CYA. 'Type' of algae does not matter.

If you suspect mustard algae, then you would raise the FC to 60% of CYA for 24 hours only, after you complete a standard SLAM.

More on mustard algae here:
https://www.troublefreepool.com/content/148-mustard-algae