Mustard Algae?

[Harbinger of Fun]

So I think this is mustard algae. It's difficult to see from the picture, but it's clearly mustard in color and is spreading daily on teh bottom of the shallow end of the pool (3.5 ft). It doesn't feel slimy, in fact you can't feel it at all as any touch makes it go... poof!

The water itself has begun to turn cloudy and has taken on a distinct yellow-green color. I am going to SLAM tonight.

My questions are: does this look like mustard algae? Should I slam to mustard algae levels? What other considerations are there if this is mustard algae? Should I clean my skimmer, brush and vacuum? How?

Stats:

FC: 9.5
CC: 0
CYA: 70
pH: ~7.4
TA: 80
Salt: 3200

 

[JamesW]

Looks like mustard algae. Regular SLAM.

 

[Harbinger of Fun]

Looks like mustard algae. Regular SLAM.

Thanks. This is only my 2nd time SLAMing. By "regular SLAM" do you mean bring FC up to (and keep it at) the 28FC shock level in the pool school CYA chart, until I pass an OCLT?

 

[JamesW]

Yes. Also, until it's gone for a day or so. It can exist and still pass an OCLT because it's so slow growing.

 

[borjis]

If it helps, I did a mustard slam right when it appeared near my shallow step area on my last pool

It took a full 1-2 weeks before it was done, brushing every day sometimes morning and evening.

Went through 36 ish jugs of 8.25% (the pool was 19,000 gallons)

 

[Harbinger of Fun]

Thanks for the advice.

I began the SLAM last night, adding 6 jugs of 8.25% Clorox "performance" bleach bringing FC up to 27 after 30 minutes. Added another jug to bring it up to 30 FC.

Waited another hour, tested before bed, down to 27 FC, so added another jug again.

Tested in morning, down to about 28 FC with about 1CC so added another jug before work.

Came home this evening, FC down to 20 but no CC. Added 3 more jugs, will test again before bed.

Once I pass an OCLT, I'll shock up to ~40ppm and hold at 40 for 24 hours, will dip all pool tools and floats for an hour or so.

 

[Harbinger of Fun]

UPDATE

Ran the regular slam @ ~30ppm for a little over 48 hours before I passed an OCLT on Friday night / Saturday morning. On Saturday morning, I then upped the chlorine to about 42ppm and cleaned thoroughly again, removed the ladder (likely my problem IMO), and soaked the equipment and floats.

Then Saturday night I can't pass the OCLT suddenly? 44ppm at bedtime became 34ppm at sunrise. Is this because I am finally killing mustard algae? Or is it expected to be difficult to maintain that high level of chlorine, even overnight?

 

[BasicTek]

I see you have others helping but I'll share what I noticed fighting mustard algae, I had to brush constantly and clean my filter (as that's where it all ended up) It can hide anywhere behind the light, skimmer, and in my case it loved the stairs and around the jets so I had to extra brush there. It can be very resistant to chlorine if you aren't brushing, then vacuuming it.

 

[Harbinger of Fun]

Prior to the SLAM, I brushed thoroughly and vacuumed to waste. I've brushed/vacuumed daily since and thrice yesterday (and soon to be today).

Fortunately, my pool has no water effects, no lights, and only two water returns plus the skimmer intake. I've scrubbed everything with a hand brush.

Upon removing my ladder, the rubber pegs in the bottom and the underside of the rungs were FILTHY!! I won't even gross you out with the pics. Clearly it was a major algae source. I sprayed with a 50/50 water/bleach solution and went to town with a toothbrush and in fact bought new rubber pegs since they were more or less uncleanable. I have not put the ladder back in yet while I debate how to more fully clean it. I set it away from the pool so any rainwater won't drain from ladder back into pool.

In terms of my sand filter... is there a way to clean it without disassembling the whole thing? Will 24-36 hours of straight filtration @ 34-45ppm Cl do the sanitation trick?

 

[AftonJeeper]

In terms of my sand filter... is there a way to clean it without disassembling the whole thing? Will 24-36 hours of straight filtration @ 34-45ppm Cl do the sanitation trick?

You can do a deep cleaning of the sand filter.

 

[Harbinger of Fun]

So something interesting has happened. After the water turned back crystal clear during the intial SLAM and stayed so during the beginning of the mustard algae shock, I've since noticed cloudy water and small bubbles attaching to the pool walls, especially near the shallow return. The bubbles foam a lot when brushed off the pool sides. The cloudiness is a strange white-colored cloud. The only thing I can think of is that it's actual bleached, dead algae that my filter hasn't filtered.

Any thoughts or insight?

 

[dkimble]

IS that oxidation? From the chlorine killing the algae? The cloudiness is dead algae, I think. Mine would get cloudy when I brushed, because it had settled on the bottom. I would go out every hour or two and brush more to keep it stirred up and hopefully to the filter.

 

[Harbinger of Fun]

I sampled some in a clear glass. The cloudiness seems to actually be very tiny bubbles which dissipate quickly. I wonder if it's related to me turning on the SWG to 100% while FC levels were still 30+

 

[dkimble]

I am sure one of the "Experts" will comment. I am far from an expert, but was curious as I am trying to learn more.

 

[Harbinger of Fun]

It's definitely the SWG, because the bubbles noticeably disappear when the SWG cell is off.

 

[BasicTek]

It's definitely the SWG, because the bubbles noticeably disappear when the SWG cell is off.

my SWG causes bubbles at lower rpm's but I don't think that would be the issue with a single speed pump. Is your pressure high/low? Hopefully someone will comment.