Calcium & magnesium question - How much?

[Nutria]

Hello
I am growing in a dwc bucket with R/O water or a mix with tap water, because I noticed some cal & mag deficiency I bought some calcium 15% and magnesium 10% from Bionova but I can't figure out how to mix them and how much of each one.
No, where I live cal-mag premixed is not sold...

I think the correct ratio is mg:ca=1:3, or not?
I should add them little by little and look at the plant but I don't even have any reference point..

 

[Maximo]

Make sure it's not a pH issue.

mg:ca 1:2

Around 100ppm calcium nitrate and 50ppm magnesium sulfate to each feed is scientifically optimal for tomatoes.

 

[Nutria]

Make sure it's not a pH issue.

mg:ca 1:2

Around 100ppm calcium nitrate and 50ppm magnesium sulfate to each feed is scientifically optimal for tomatoes.

I don't think it's pH related since I try to check it daily and it's stable.

So next time I change res water I should add mag till I get a reading of 50ppm then calcium for a total of 150ppm.

But looking at Botanicare Cal-Mag page it says:
Nitrogen (N): 160-250 ppm
Calcium (Ca): 160-280 ppm
Magnesium (Mg): 45-75 ppm
Iron (Fe): 2-7 ppm

So a ratio of about 1:3

 

[DRM Ranch]

I would start with 1:2 magnesium to calcium and adjust based on the plant response.

I've managed to get away without a CalMag supplement using RO water with a sub 25 PPM output using DynaGro nutrients, so a lot is going to depend on your water, the nutrients you use, and the plants themselves.

Good luck!