What would that be for?

I cut the water again with RO, so now it's (mathematically calculated) down to about 20ppm Ca and 12ppm Mg. It measures at about 6 dGH and 2 dKH.

After the dilution I got a fizz factory of pearling yesterday and today, mostly out of the Mexican Oak Leaf, but still no significant leaf growth. The red plants, mostly ludwigia species, aren't budging at all. I'm ready to dump them, but the plant I want most to get going is plain old hygrophila difformis. I know what this plant is capable of doing, and this ain't it.

Same pattern as I've had for some time, a spurt of activity after a change, then a steady decline into choking by the green fuzz algae that follows green dust algae. If I could get the fast leaf growth I've had in the past, the plants out run the algae and it can be physically removed into oblivion.