Fighting Algae with Borax

[chem geek]

topless,

I'm glad the Borax is working for you and it's good to know that it seems to inhibit yellow/mustard algae. Prior to your experience, we only saw that it seemed to inhibit the much more common green algae.

By the way, to shock yellow/mustard algae we figured out (through a few users experiences on this forum) that it takes lowering the pH to 7.2 and then raising the FC to 60% of the CYA level (instead the usual 40% for green algae) and holding it there for at least 2-3 days. In your case that would have been 30 ppm FC. Then to keep away the yellow/mustard algae if it gets reintroduced it would take a minimum FC level of 15% of the CYA level or 7.5 ppm FC in your case. In this post you said you had to shock at 25 ppm FC or else the yellow/mustard algae would return in a few days. So that's close to the 30 required for shocking this algae, but was the subsequent maintenance level required to keep it away 7.5 ppm or something else -- the post sounded like dropping anywhere below 25 ppm FC would have the algae return? I just want to confirm that you weren't seeing anything inconsistent with "first 7.2 pH then 30 ppm FC shock then 7.5 ppm FC maintain" at 50 ppm CYA, since this is the advice we are currently giving (and now we can say that Borates will help as well).

Richard