Possible to pass all algae tests and still have algae?

Goob

Gold Supporter
Oct 20, 2015
118
Magnolia, TX
Built the pool two years ago and have been very good with testing and balancing. We have fortunately never had any algae problems- until now.

Is it possible to have algae growth (rhetorical, as I don't know what else the green could be) when my OCLT showed no loss, my CC is zero and the water is clear?

Over the last month ranges (current in parenthesis)-

FC 12.0 - 4.5 (5.0)
pH 8.0 - 7.2 (7.7)
TA 80 - 60 (70)
CH 500 - 425 (425)
CYA 70 - 50 (70)

My wife says she missed a brushing before we saw this (brush every 3-4 days).

I'm going to SLAM but with my current readings showing that there is nothing present, how do I know when to stop?

Appreciate any experiences shared. First time for me but I expected some whacked out readings to help me out, not just the good ol' eyeball!
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
Better info, please. What's green? The pool sides? The pool floor? green tint to the water? I am sure it is algae as well but let's get clarified where it is.
 

Goob

Gold Supporter
Oct 20, 2015
118
Magnolia, TX
Oops, sorry. Rewrote most of my post and that part was left out.

Floor and sides, both pool and spa. When I brush a surface, a green cloud kicks up. Water doesn't really look green. Picture doesn't show it too much and it isn't a full green but it is starting. The corner shows more of what I can see with the eye.

IMG_6248.jpeg
 

JamesW

TFP Expert
Mar 2, 2011
16,599
CC is really not related to algae.

It is possible to pass the OCLT while you have algae.

You need to SLAM.
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
Yeah, I agree with JamesW. It doesn't show well but It looks like dead algae on your pool floor.....incredibly common and it is the result of LIVE algae in your pool. The tests are not 100% all the time but SLAMming your pool (correctly) will fix your pool and get rid of that debris.
 

Goob

Gold Supporter
Oct 20, 2015
118
Magnolia, TX
CC is really not related to algae.

It is possible to pass the OCLT while you have algae.

You need to SLAM.
Granted, but shouldn't there still be some type of CC reading with algae and proper levels of FC? Again, first experience with this so I'm just trying to understand why there isn't a reading with the CC.

On the flip side, back to my second question, how will I know when to stop if the three items in Pool School (CC, OCLT, and water clarity) seem to pass? The same way I knew to start, visually?
 

Goob

Gold Supporter
Oct 20, 2015
118
Magnolia, TX
Yeah, I agree with JamesW. It doesn't show well but It looks like dead algae on your pool floor.....incredibly common and it is the result of LIVE algae in your pool. The tests are not 100% all the time but SLAMming your pool (correctly) will fix your pool and get rid of that debris.
Ahh, a new one for me. Never realized that algae could have debris, but it makes sense.

I'm going with the experts!

You two are always great with your advice and help! You both make owning a pool less menacing.

It's in the reply above, but how will I know when to stop? When there is no more debris on the floor? Also, should I run the robot every day/every other day to help get the debris out?
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
CC readings in your pool will fluctuate and a CC result of 1 ppm or higher is an INDICATION there are organics in your pool but it is not guaranteed.
how will I know when to stop if the three items in Pool School (CC, OCLT, and water clarity) seem to pass?
You didn't pass water clarity. TFP's definition of water clarity includes NO VISIBLE signs of algae
 

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
You'll get rid of that debris during the SLAM when you brush and vacuum your pool. Brush the sidewalls and vac the floor once daily if you have the time. Every other day is probably adequate.
 

Dave31410

Bronze Supporter
Feb 27, 2018
120
Savannah, GA
Not an expert, but I have found that brushing is important. There can be dead spots in the pool circulation where a boundary layer can form adjacent to certain spots of the pool surface. While the overall Cl reading can be acceptable, these boundary layer spots can be low in Cl and algae can develop.
 
  • Like
Reactions: JamesW

duraleigh

Admin
Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
32,859
Sebring, Florida
Not an expert, but I have found that brushing is important. There can be dead spots in the pool circulation where a boundary layer can form adjacent to certain spots of the pool surface. While the overall Cl reading can be acceptable, these boundary layer spots can be low in Cl and algae can develop.
Dave makes a good point to emphasize how we cannot ALWAYS rely on hard test results. Test results are the very basis of TFP teachings but they are not the end all-be all
 
  • Like
Reactions: JamesW