Is it Mustard Algae

[benavidescj]

I recently found a small, quarter sized, brownish looking (almost like dirt) on the first step into my pool. This first step is about 4 inches under water and possibly has bad circulation. I picked it up and it was slimy, brown and almost translucent. I scrubbed it with my 50/50 brush and it was hard to get rid of the stain behind it, but it came off.

Anyways, I started to get worried so last night I did an overnight FC test and my FC went from 10 down to 7.5 this morning. The water is clear and CC is .5 or less. Is this stuff mustard algae? My current CYA is about 70 and what I don't want to do is spend large amounts of money to achieve mustard algae shock levels when it might be a lesser form that I could kill with regular algae levels.

Readings:
FC - 7.5
CC - .5
CYA - 70
CH - 320
TA - 80
pH - 7.7
Salt - 3400
Borates - 10

 

[RobbieH]

In my experience, mustard algae looks like dirt on the side of the pool, greenish brown, and makes a yellow cloud when you brush it. Did you get a cloud when you brushed?

Found a YouTube video, it's even on his steps.
http://www.youtube.com/watch?v=wAIodu0TaK0

Note it comes right off and forms a yellow cloud.

 

[duraleigh]

Is this stuff mustard algae

No, I don't think so either. Robbie has described it well. Normally on the walls but the real identifier for me is the greenish-yellow cloud it turns into when you brush it.

 

[RobbieH]

Yea, I learned from experience. I'm going to blame it on the previous homeowner neglecting the pool after I signed the contract.

 

[benavidescj]

I got a cloud but I am pretty sure it was white and I was getting it all the way down the thin strip of pool surface over the step. Pretty sure the cloud was just that the surface, in this hard to reach area, had not been brushed since the pool was built last year. So my plan is to just shock at normal algae levels for my CYA.