Possible mustard algae but tests show 0.0 combined chlorine

[sonnaps]

Hi All,

I have a couple of questions about combined chlorine and signs of mustard algae. I am currently only using liquid chlorine for my sanitizer, no pucks. I have been doing that all season because of high cyanuric acid levels, but those are now back to normal after draining and filling multiple times slowly the last few months. I adjust the chlorine every night to stay in the 2-3ppm range. I counter act that with muriatic acid to keep the pH in check. I also keep on eye on the alkalinity and adjust accordingly. I have managed to keep my combined chlorine at 0 all these months. Maybe once or twice it was at 0.2 or something after a heavy rain. That cleared itself up on it's own with a little extra chlorine.

Every week or so I see what looks like sand in two or three areas around the perimeter (not near the return jets really). I chocked it up to possible fine sediment from the new zeolite that was added to our sand filter when we changed the sand this season. I did come across this video, though, which made me think a bit more on it:

When I brush the small pile I see, it does plume up like in the video. It does not sweep into a pile or anything. It's usually in a seam in my vinyl liner.

So to my questions:

1. Do you think it could be mustard algae?
2. Would my combined chlorine be showing as 0 if I indeed have mustard algae?
3. Should I shock just in case even if my combined is at 0? I would bring my chlorine levels to about 12ppm with liquid chlorine. Would I be doing any damage to anything or am I wasting my time and chemicals?

Current Levels:
21,000 gallons, vinyl pool
Chlorine 2.6
pH 7.6
Alk 110
CYA 35
Calcium 200
Copper 0.43 (issue I was having all season, got it down finally from 3.2)

 

[duraleigh]

1. No.
2. A positive CC test does not always mean algae......of ANY type. It is an indicator that
3. Yes, you need to SLAM the pool. That's dead algae on your pool floor meaning there is some live algae in your pool water. Please read "Pool Care Basics" up in Pool School

How did you get rid of the copper?

 

[sonnaps]

1. No.
2. A positive CC test does not always mean algae......of ANY type. It is an indicator that
3. Yes, you need to SLAM the pool. That's dead algae on your pool floor meaning there is some live algae in your pool water. Please read "Pool Care Basics" up in Pool School

How did you get rid of the copper?

Can you clarify #2? It is possible to have algea with 0 combined chlorine, correct? And having a postive combined chlorine doesn't always necessarily mean algae? That one I knew. First part is what I am questioning.

For the copper, I used two rounds of this Metal Stain Eliminator kit with Culator 4.0 PowerPaks in the skimmer and pump baskets. I did this twice over several months while keeping the pH on the low end of normal throughout. It was painful but it worked. I choose this method over other sequestering agents that would skyrocket my phosphate levels. The copper came from a deteriorated heating coil in the pool heater. The heater has since been replaced.

 

[duraleigh]

Sorry, I mistyped that answer.

You can have a 0.0 cc result and still have algae. The combined chloramines test simply tells you that the chlorine is combining with something organic in your pool. TFP believes 1.00 cc results is a reason to perform the SLAM process.

Anything less than 1.0 is typically a normal, everyday occurrence and will usually go away on it's own.........but, there can still be SOME algae in your pool.

Nice work on the copper!

 

[sonnaps]

Sorry, I mistyped that answer.

You can have a 0.0 cc result and still have algae. The combined chloramines test simply tells you that the chlorine is combining with something organic in your pool. TFP believes 1.00 cc results is a reason to perform the SLAM process.

Anything less than 1.0 is typically a normal, everyday occurrence and will usually go away on it's own.........but, there can still be SOME algae in your pool.

Nice work on the copper!

Ok, makes sense then, thank you. So you would SLAM if you were seeing this sandy stuff every now and then?

Based on that Chlorine/CYA chart, to SLAM I would bring my chlorine to only 4-7 ish?

If my combined is 0, should I just do it one night and that's it? More like a shock than the entire SLAM process?

 

[duraleigh]

seeing this sandy stuff

I doubt it is "sandy" I don't think you will be able to pinch it between thumb and forefinger........It's dead alga and it will "poof" away if you try to capture it.

TFP doesn't suggest shocking the pool. Our terminology and methods call for a full SLAM to get your pool clean once and for all,

Re-read the SLAM process. With CYA of 40, your SLAM FC should be about 16, I think.