Insight please

[Imracerx]

My pool water is crystal clear but I am noticing that I am getting yellow algae in areas. I have no CC when I tested the water and the filter has just been cleaned. Do my test results look ok? One other question, should I raises my CYA to eliminate Chlorine loss? If so, what should I raise it to?

FC 3.5, add some Chlorine now at 6
CC 0
CH 400
TA 100
PH 7.6
CYA 38

 

[Texas Splash]

Hello! Let's round-up your CYA to 40. Based on the Pool School - Chlorine / CYA Chart, your typical FC should be 5. So if it stays too low for a significant amount of time, you may very easily start to see the on-set of algae. But in your case - yellow? Some algae yes, but I almost wonder if the yellow isn't more related to pollen. In any case, you might want to check around the pool and other surfaces nearby to see if you do in-fact see pollen settling. If not, and if the yellow appears to be isolated ot the pool itself, you may want to perform an Pool School - Perform the Overnight FC Loss Test (OCLT) to see if there is something consuming your FC.

When performing the OLCT, remember that it must be done when the sun has dropped – no sunlight on the pool. About 8 hours total is recommended. If you use a SWG or automatic chlorinator, make sure they are turned-off or set to zero. Also, your FC level should be elevated more than normal. Starting (bedtime) FC could be close to your SLAM level, but no lower than 10. Anything less and you may not receive an accurate portrayal of FC loss (by percentage), even if it’s only 1 ppm.

As for raising the CYA above 40 - you can if it is warranted. You'll know if your CYA needs to be higher when it is confirmed there is no algae and your FC is still being consumed too fast by the sun. Then you may need more stabilizer (CYA) to protect it. But first consider the OCLT to rule-out any algae if you are sure pollen is not an issue. If you do try to raise CYA, I would suggest dong it in increments of 10 ppm.

Hope this helps. If you have any other questions, please let us know.

 

[zea3]

Are you sure its yellow algae? Is it growing on the walls on the shady side of the pool or is it collecting at the steps and waterline? We've already got trees budding out here and I had a lovely dusting of yellow pollen on my red Camry.

 

[Kiss4aFrog]

Is there a chance you've been dropping down below 3ppm FC lately ??

 

[Imracerx]

I dropped to 2.5 once. Yes, the algae is collecting in the shady areas. It's not pollen since its on the walls.

I will do a OCLT tonight.

 

[Texas Splash]

Since you appear to have ruled-out pollen, Mustard Algae (MA) could be the culprit. It is a yellowish color and grows on the walls and floor mostly on the shady side of the pool. Mustard algae will continue to spread and grow up the walls of the pool if you don't treat by SLAMming the pool. When performed properly, a SLAM can remedy MA as long as you are at the proper shock level for your current CYA and brushing frequently. MA is treated initially just like a regular "SLAM". Once the regular SLAM has passed all 3 criteria, the pool is treated by 24 hours of a higher FC level for MA treatment as a final "punch" to remove it. Please review the following pages and follow the instructions to the letter. If you have MA, it will work.

Pool School - Mustard Algae and Pool School - SLAM - Shock Level And Maintain.

 

[Imracerx]

Thank you!

 

[kimkats]

Brushing and more brushing will be your friend. You have to get that stuff out into the water for the chlorine to kill. I would try for at least twice a day.

Kim

 

[Patrick_B]

I would prepare for a SLAM with the information in the links you were given. If you haven't already, dont increase the Cya level. If it's MA, its harder to kill and you can't let the FC drop, or you'll never kill it.

 

[duraleigh]

As posted above, brush your pool.

Brushing is mandatory for the chlorine to kill the algae.

 

[Imracerx]

So the result of the OCLT is that I passed. Started at FC-16 and finished at FC-16. I guess that is good news. I will be better at brushing.

If you see anything else I should be doing please let me know.

Thanks again for the help as I am still learning TFP.

 

[Kiss4aFrog]

You passed the OCLT, are you still seeing the yellow stuff on the walls before you brush ??

 

[Isaac-1]

To answer your side question about CYA, once you get the algae issue all under control, you may wish to raise your CYA, but that does depend a bit on the pool, its location, sun exposure, etc. You seem to be in a rather dry part of southern California near the border, so likely prime sunbelt location. If your pool is exposed to full sun all day then, yes you probably want to go up to about 50 ppm on your CYA, however if by chance your pool is in a shaded or partly shaded location you are probably ok with your CYA at 40 ppm. Once again don't change it until you get the current issue sorted out.

Ike

 

[Imracerx]

You passed the OCLT, are you still seeing the yellow stuff on the walls before you brush ??

Yes, I am.

- - - Updated - - -

To answer your side question about CYA, once you get the algae issue all under control, you may wish to raise your CYA, but that does depend a bit on the pool, its location, sun exposure, etc. You seem to be in a rather dry part of southern California near the border, so likely prime sunbelt location. If your pool is exposed to full sun all day then, yes you probably want to go up to about 50 ppm on your CYA, however if by chance your pool is in a shaded or partly shaded location you are probably ok with your CYA at 40 ppm. Once again don't change it until you get the current issue sorted out.

Ike

Thanks! The pool is in all day sun.