Hey satori, what's with you and the CalMag.. LOL!! I've never used it! Never needed to with ANY system or medium in 20years. I dont get it. It aint a cure all. It just makes the herb taste like shit.
the amount of calmag depends on the amount of calcium in the source water and depends on how much K is in your mix
if your source water contains calcium you may get by without
if your mix is high in K it takes more calcium to achieve a balanced ratio between cations potassium, calcium, magnesium
and partly it depends on your medium, for example soil is more forgiving than aero so maybe in soil or coco you might not need it in some cases because of its buffering
but when I figure out a mix for someone I figure it as if there using RO water
if they end up having calcium in the source water its usually not enough to throw out the ratio
since I have the technaflora nutes open on my page (I have many brands saved) I will use them as an example
using just the base nutes for veg
12mls boost
6mls grow
that mix yields
N 111ppm
P 21ppm
K 132 ppm
Ca 100ppm
magnesium 17ppm
ideally during veg your k:Ca:Mg ratio would be 3:2:1
you can see from the mix above theres already plenty of calcium, actually slightly more than needed but still in the margin of error... but you can also see the magnesium is grossly def
speaking in terms of ideal those numbers would say
K 132
Ca 88
Mg 44
giving a perfect 3:2:1 ratio
so to balance the veg mix we need to add 1tsp Epsom salt which adds 26ppm of magnesium which bumps up the magnesium from 17ppm to 43 ppm
in the end the mix is about 10ppm high in calcium but theres a margin of error +/- so its fine
typically as long as the magnesium is half the calcium your in good shape
now looking at the bloom
8mls boost
4mls bloom
1mls awesome
yields
N80
P31
K120
Ca 68
Mg 9
the ratio in late bloom for the cation between K:Ca:Mg changes to 4:2:1 when the K needs go up
in this case he may be able to do without the calcium from the calmag if theres some small calcium in the source water
but
the iron levels in the base mix dropped of with the reduction in the boost so adding 1mls calmag increases the iron slightly
1mls calmagic adds
5ppm N
3ppm Mg
9ppm Ca
Fe 0.3ppm
which changes the final mix to;
N 85ppm
P 31ppm
K120ppm
Ca 77ppm
Mg 12ppm
then we add the 1/4 tsp Epsom salt to get the magnesium up which adds 25ppm Mg bring the final magnesium number up from 12 to 37ppm
if he then bumps the awesome up in late flower itll boost the p and K and give him the 4:2:1 ratio between K:Ca:Mg
for example final mix in late bloom with extra awesome;
8mls boost
4mls bloom
2mls awesome
1mls calmag
1tsp Epsom salt
N 85ppm
P 44ppm
K 145 ppm
Ca 77 ppm
Mg 37ppm
leaving him with close to a perfect 4:2:1 ratio between +/- between K:Ca:Mg during late bloom
re-cap
so again if I know for sure hes got 9ppm calcium in his source water and maybe some iron then he wouldn't need the calmag
if you can get the ratios for K:Ca:Mg balance +/- youll never have an issue