any way to control pH better?

[PoolDoc]

OK, here's one of Furbyvet's pool pictures with my notes and editing:



Several things to note:

FIRST: Black algae isn't; it's dark green. It appears black when it's thick, or underwater. But if you'll use the 'smear test' -- scrape some with your fingernail, and then smear it on a white card -- it will always appear green to dark green.

SECOND: The scale visible at the top may be calcium carbonate, or it may not. In the Southwest, their drinking water is sometimes so full of minerals that people can 'mine' it! As a result, they can get quite creative with their scales! The easy test is acid: if you flake off a bit, and drop some muriatic acid on it, it will foam or fizz if it is calcium carbonate.

THIRD: Exposed mortar grooves -- between tiles, between pebbles, in cracks and crannies, around light niches or skimmers is algae's refuge. It's always difficult, and sometime impossible, to get enough chlorine or other algicide into those spots to kill off the algae. In this part of the country, I wouldn't even consider a commercial pool management contract on a pool with a surface like that, unless the customer accepted a VERY large algae management surcharge. There's no shortcut to physical cleaning, and you have to do lots of it on a heavily loaded commercial pool with a low quality surface (= equals any surface with LOTS of algae hidey-holes). Very, very expensive glass tile pools, with poor quality grout joints (= rough and/or porous) can be a total nightmare to maintain. Beautiful, but extremely 'high-maintenance'!

FOURTH: What's particularly interesting here is that Furbyvet's algae has found a home at the 'high tide line', where it's wet enough to live (because of the grout joints holding moisture) but low enough in chlorine (because it's outside the circulation system) for the algae to be quite happy.

FIFTH: People, including some pool book writers, often think that black algae or mustard algae or green algae is a species of algae. But, in fact, the names are nothing but a physical description. Black algae is black looking, and surface clinging. Green algae is free floating and not obviously connected to the biofilm layers associated with it. But, in fact, all forms of algae tested by some researchers I've spoken to in the past, were FAMILIES of both bacteria and algae. This is especially true of any biofilms, like the slime that precedes green algae outbreaks, or like black algae. My recollection is that the lowest number of identified species in any single occurrence was over 20, and always included both algae and bacteria.

PoolDoc