New Thread with my results of first test

[Tom.B]

Mustard algae will re-appear in areas where you've brushed or wiped it off. It is usually on the shady side of the pool, and will appear on vertical surfaces.

Is there any way to know for sure what algae I have?

[BigDave]

If it's yellow-ish (brown-harvest-yellow-chartreuse), it lays on the bottom and brushes up easily then returns, and is resistant to chlorine, I'd call it mustard algae.

[PoolDoc]

Is there any way to know for sure what algae I have?

Not really. It's not a species of algae; just a 'behavior' of some algal biofilms. Some years ago, I spent quite a few hours chatting with a senior researcher at Buckman Labs (inventor of polyquat). He told me that every single case of algae he'd studied, including samples from his home pool, involved more than 10 species of algae AND bacteria.

But Dave's description of the 'behavior' is accurate, with the addition that it's (a) often found on the bottom AND sides, and (b) typically is first found in shaded areas of the pool. It *will* 'bloom' and turn the entire pool green if not controlled.

[Tom.B]

Okay then... I suppose that I have it then. I guess I will read about it here and see what I can do about it.

[PoolDoc]

Mustard algae options:

1. Run chlorine levels at the 'algae' or 'shock' level continuously -- see http://pool9.net/cl-cya/ -- and brush a lot.

2. Run normal chlorine levels + maintain phosphate levels below 125 ppb (0.125 ppm).

3. Use lots and lots of copper, turn everyone's hair green, and stain the pool.

I'd recommend #1 first, especially if you've never had mustard algae before. If your pool is not one of the not-so-lucky ones prone to mustard algae, it may stay gone after you've cleaned it up.

But if you find you're struggling to keep it away, we can look at option #2. However this requires managing phosphate additions to your pool from multiple potential sources, including the fill water.

[Tom.B]

I belive that I *may* have had it for a while, but my phosphate level is low. I will run up the chlorine levels this week and see what happens. I read a thread about using commercial algae treatment, is that off the table or should I just try the chlorine method first?

[PoolDoc]

How do you know that your phosphate levels are low (< 125 ppb)?

If you didn't test with one of these two tests, you probably do NOT know. There are some VERY inaccurate tests being sold. Keep in mind, pool dealers make money by selling you chemicals, NOT by solving your problems. If they DO solve your problems, you won't see them very often. I'm not saying there are no honest dealers, but I'm saying that the ONLY incentive pool dealers have to be (a) honest and (b) accurate is their own moral values. Financially, honesty will hurt them rather badly.

The AquaChek is easier, but only useful below 500 ppb; the Taylor is 'fiddly' to use -- the test cell tends to fall over -- but more functional over a full range.

Hach (AquaChek) 562227 Phosphate Test Kit
Taylor Technologies Inc K-1106 Test Kit Phosphate

Still, getting your chlorine levels up, is the first step.

[Tom.B]

You keep mentioning this, and as I said on Post #5, I have the Taylor kit and ain't afraid to use it :-D

So all I can tell you is that the phosphate levels are at, or near, 125 based on that kit and hasn't changed much since I started testing (at the beginning of this thread). ;-)