I would have been mixing my own nutrients already if I had the space- its unbelievable how cheap and customized you can get. And if you read around enough (especially agriculture white papers) you quickly realize how much more simple and direct dealing with nutrients is.
Found a recipe yesterday for a micro solution that doesnt contain calcium. Basically its a 3-part solution with calcium being its own part- only chelated nutrient needed is iron. In part you're getting screwed with expensive and complicated chelates just so they can sell you an A/B solution while shipping the least amount of water as possible- the thing we all have pretty easy access to.
Plus all of these 'magic' pH buffers which you'll mostly be scraping off of the bottom of your rez after it precipitates out (can't buffer forever). GH ph downs 'premium buffer'- Ammonium dihydrogen orthophosphate- basically the stuff they use in those crystal growing sets for kids. And people are worried about sulfuric acid being toxic? Phosphate buffers also have a tremendous ability to react with calcium as a precipitate, which basically acts as its own up buffer. You're leaching and locking ions in your solution just because "ph buffering" sells well.
If you read around more, you'll find that calcium and magnesium are often used for phosphate removal (by precipitation). This also raises ph! You're fighting a war that you really don't need to fight and you're probably giving yourself calmag defs. Sulfuric acid is a unique (and highly energetic) acid that is often used in combination with other acids to make them more effective. It is very stubborn as far as giving up the SO4 ion- meaning its more likely to stay an acid, and not 'reduce' itself down to a more stable state. Pretty much any white paper on hydroponics i read uses sulfuric acid or sometimes nitric acid as a down, and sometimes citric acid as a buffer.
The only danger you have with sulfuric acid is Calcium Sulfate precipitation- which is still between 20-200x more soluble than most calcium precipitates- and I think even that can be mitigated by using nitric acid first. Citric acid can also be used to chelate calcium (this is why there's citric acid in GH ph down- attempts to avoid precipitates), but it is rather weak, and works best when applied to the solution while still alkaline.
Meh, I'll just drop this sorted solubility list here if anybody is interested (at 15 C, most soluble first, units in g/100ml):
Calcium nitrate 121.2
Magnesium nitrate 69.5
Magnesium acetate 53.4
Magnesium sulfate 35.1
Calcium acetate 34.7
Magnesium citrate 20
Calcium sulfate 0.255
Calcium citrate 0.095 (25 °C)
Magnesium carbonate 0.039
Calcium phosphate 0.002
Calcium carbonate (Calcite) 6.17×10−4
Magnesium phosphate 2.588×10−4
But if you look at where the phosphates are, and read about how phosphorus cycle works in soil... it seems kinda obvious you want to avoid them as much as possible in hydroponics (at least in runaway amounts like you might end up with in a ph battle).
hope you are doing well man 
