When to stop SLAM process with yellow algae?

[evan567]

Hello,

Some backstory: I've been battling an issue with brownish colored spots showing up on bottom of pool. At first I thought it was yellow algae but then reading more about it it didn't meet all the criteria. It grows all over including areas in the sun, not on the walls, and different overnight tests I did never showed a chlorine loss over 1.

Well, I stopped cleaning for like a week and the walls started to get gunk on them. This was mainly on the corners where the floor and wall meet. I was trying to maintain chlorine but there was a moment where chlorine dropped to around 2, maybe lower, at a CYA level of 30 (I only used the liquid drop test in this moment so don't have exact measurement). So it is completely possible it was an unrelated algae bloom but could also be that since I wasn't cleaning regularly it allowed the yellow to spread? When slamming that away I decided to just try slamming for the brown spots in case they are algae.

Back to my question: Right away the wall gunk was resolved but I still have brown spots 2 weeks later. There's maybe a slight improvement in the amount but that could also just be from the daily brushing and vacuuming. My understanding is that visible algae being gone is one of the requirements to stop the SLAM but yellow algae requires a higher level of shock for 24 hours.

Should the yellow algae be gone during the normal SLAM process prior to the 24 hour shock? Or should I complete all the steps except the visible algae part and then do the 24 hour shock?

 

[Texas Splash]

The SLAM Process, when applied and followed properly, will resolve the majority of algae issues. But it is critical to follow that page closely and maintain the proper (elevated) FC-SLAM level until all 3 SLAM criteria are completed. Anything less and you're just wasting time, chemicals, and money.

Once an owner passes all 3 SLAM criteria, if there are residual stains we can address those at that time. Hope that helps.

Algae Archives

www.troublefreepool.com

 

[Texas Splash]

Also be sure to update your signature. See mine as an example. The link below may help.

Create Your Signature - Further Reading

www.troublefreepool.com

 

[evan567]

Thanks for the response but that doesn't really answer my question. The mustard algae page says to complete SLAM then do 24 MA SLAM because MA is resistant to chlorine. But one of the requirements of completing SLAM is that there is no algae. To me, there is a contradiction there. You cannot complete SLAM to get to the MA SLAM levels because you need MA SLAM to kill the MA.

Unless it does disappear during normal SLAM which was what I was wondering. Based on what I'm reading on the page it sounds like it is supposed to go away but just wanted to double check.

 

[Texas Splash]

But one of the requirements of completing SLAM is that there is no algae. To me, there is a contradiction there.

The 3 SLAM criteria are:
- Pass the Overnight Chlorine Loss Test
- Clear water
- CC of 0.5 or less

Obviously you don't want to see algae. If you do, then you continue with the regular SLAM Process. If someone is confident they have Mustard Algae (MA), only after passing those 3 SLAM criteria do they increase the FC to the MA level, but only for 24 hrs. By that time there should be no visible algae, but residual MA spores may be present in the pool surfaces and accessories (toys, cleaners, etc) which is why the 24 high FC level is required.

 

[Getitrite]

You read Mustard Algae correctly. First sentence -

"Mustard algae is a particularly persistent kind of algae, that appears to go away when you SLAM the pool normally, only to reappear as soon as you come back down to normal chlorine levels."

 

[evan567]

Ok so normal SLAM should clear up visible algae and MA SLAM is for residual spores. Thanks.

I've been checking levels and adding at least 4 times per day. Is that not enough? Chlorine drops pretty fast and often see it around 8 ppm, when the target is 12, while testing. But realistically can't check it every hour. Not sure if that chlorine drop is normal when at elevated levels. Or if it is algae and it is just persistent. Or if my CYA isn't high enough for type of sun it is getting because did notice higher drops on days with higher UV indexes.

Feeling defeated because I'm not confident it is MA. That's why I wanted to double check my understanding. Appreciate the responses.

 

[Texas Splash]

4 times per day. Is that not enough?

You would think so, and in many cases that is a very good effort. Some pools experience a more aggressive FC loss, so if yours is still doing that, you may find yourself testing a bit more frequently until the FC becomes more stable. Yes, having a CYA on the low end may allow the sun to steal more FC during the day than we would like. But i's a bit of a trade-off during the SLAM to save on chlorine with a lower CYA.