[shrimpchips]

Just wondering, how stable is your Mg?

A combination of high pH, Ca and Alk causes even higher supersaturation of Ca and Co3 in the water making it more likely to precipitate. Mg interferes with the process, so keeping a high Mg can assist in staving off precipitation.

The change in Alk buffers I'm suggesting is for two reasons: 1, to lessen the impact on your salinity (by adding half the sodium during dosing), and 2, to lower your pH.

Also, see what boosting your Mg to 1400 - 1500 does for you. Might be just as frustrating getting Mg up (and to stay up!), but it'll help keep your CaCO3 from precipitating.