Randy, I’ve read through your “A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and PH” several times and I think I understand the relationships now. I have a few questions about what I’m seeing in my system and wondered if you could help me with the logic tree for what I’m seeing And what to do, if anything, about it.If by "neutral point" you mean 7 dKH, yes, it can drop further, but the precipitate slows as it gets lower and lower. The exact lower limit in alk that can support precipitation depends on pH, but at pH 8.2 it can theoretically drop below 6 dKH.
First, from my discussion above about my 75 gallon saltwater reservoir. I stopped the pump and looked in with a flashlight and yes, there is quite a bit of precipitant in the bottom and all up the sides. Hard and crusty. When I add fresh salt (or sodium carbonate) the PH would rise to 8.2 and Alk rise to 9.7. Test again in 24 hours and it’s back to PH of 7.9 and Alk at 7.7. I assume from your article that the water is quickly return to equilibrium by precipitating calcium carbonate. Question is, does the excess calcium carbonate precipitant buildup in the tank allow/cause/accelerate the rapid drop in PH and Alk back to their lower levels? Will cleaning/removing the build up allow for higher semi-stable numbers of PH and Alk.
Second, in my DT, I am seeing quite a bit of white particles on the bare bottom and on the rock structure. Would this also be calcium carbonate precipitation? Right now I am dosing 3 ml of Brightwell Reef Code B Alkalinity a day. Not dosing Ca or Mag because those numbers are high. Parameters are fairly stable at PH 7.95, Alk 7.9, Ca 500 and Mag at 1590. Lights are still at fairly low levels but I’m slowly increasing then weekly for coral acclimation. System is at 10 months old and all corals and fish appear very happy and growing. I am also staring to see small patches of coraline starting all over the rock structure. Question is should I worry about the precipitation, or is that fairly normal as the system finds it’s sweet spot. Also, should I be concerned with elevating my Alkalinity to the 8.2-8.4 range, or just leave it alone since it seems quite stable.
Thanks in advance.
Jetson