Randy rating for the first discussion, D. Not at all good. The first paragraph is fine. The recommended alk/calcium combos isn't very good, one of its two combos is so low in alk that it should not ever be recommended unless one is doing a low alk experiment (IMO). I have no idea where it is getting these sorts of combos from. It doesn't seem based on any protocol I can think of. The second one nearly doubles the alk but hardly changes the recommended calcium. The concluding paragraph is terrible. I do not recall anyone ever suggesting that if alk is lower, calcium should be higher, and certainly not for the reason mentioned. Maybe someone has, and that is what this whole paragraph is keying on, but I haven't seen it.
Randy rating for the second discussion, F-. I'd give it lower than F- if I could.
This is the article the AI was referred to:
http://reefkeeping.com/issues/2002-04/rhf/feature/index.htm
The AI says there is a generally recommended ratio of calcium to alk to magnesium of 3:1:0.1. It then says that calcium should be TEN TIMES the magnesium concentration. That is not even what its ratio says (which is 30:1). OMG (F- for that alone) It doesn't give units of measure at all, so its pretty hard to compare alk to calcium and magnesium. It hard to know what it is thinking, but my guess is that it is looking at these values IN a coral skeleton, and then deciding that would be a good target level in the water. I definitely said no such thing in the article. I never gave (and never do) give ratios for target levels.
The whole calculation section is ridiculous. I never once in the article or anywhere else claimed that one can calculate optimal alk and calcium concentrations from each other. I have no idea where that came from. I'd very surprised it literally says the article provided such an equation.
Here's the final kicker.
Let's look at the equations it devised:
Let's assume alk is 7 dKH and thus 2.5 meq/L.
The first equation recommends calcium be 2.5 x 2.5 x 50/17.9 = 17.4 ppm
The second equation recommends magnesium be 4.11 x 2.5 x (50/17.9) x 0.1 = 2.9 ppm.
Nice. the AI recommends optimal values for a reef tank to be 7 dKH, 17 ppm calcium and 2.9 ppm magneisum.
Sounds more like tap water. lol