Thanks for the title.

I'd seen all that info from Richard ('Chem Geek') before, but I don't recall that article, where he put it all together. And yes, Chem Geek digs in deep on the chemistry, something I can't do. The upside of all that is that he took the empirical observations I'd made ( + some inferences I'd worked out from a paper by an Olin chemist, who'd read the O'Brien article) and did all the work to validate those observations theoretically and analytically. It looks like he's finally succeeded at get the pool industry as a whole to take notice!

OK, a bit more about green.

I've seen 'green' water from 3 things: algae (commonly), iron (occasionally), and something weird, possibly having do to with high alkalinity (very rare).

The differential diagnostic is backwash color: brown is algae, orange is iron, and ?? is alka-what?.

However, you can NOT trust dealer testing. Period. It's not that all are bad, but rather that a majority are, and by the time you know which is which . . . you are already testing it yourself.

In your case, get BOTH a K2006 and a K1106 (phosphate) kits from Amazon.

Forget about the NoPhos. Natural Chemistry is NOT trustworthy on any product not % labeled; concentrations vary under the same label! If you want to do phosphate removal, order 1 quart per 10,000 gallons of PR10000 on Amazon. I've decided to attempt a local chem-service with phosphate removal as a core element, so I'm not going explain everything. But the basic points of phosphate removal are that
1. It works ONLY IF you do it right.
2. You must maintain PO4 levels < 100 ppb (0.1 ppm) at ALL times.
3. You must avoid ALL combo chemicals, some clarifiers, and most stain control agents, because they add phosphates.
4. Phosphate input rates to your pool vary, for multiple reasons I'm going to keep to myself. So, periodic testing and dosing MUST be part of your routine.

You should do the backwash color check ASAP. You need the K2006, regardless. The phosphate stuff is your choice, but don't bother if you aren't committed to the continuing routine.

Good luck!