<span class="link_user">@wolfvb</span>, Some people might be interested in making their own calcium and magnesium solutions. For pennies. That could be a good starting point. Magnesium is easy, epsom salt. Added benefit of sulfur for bringing out nice flavor. Dissolves in water. But calcium carbonate or egg shells crushed finely have to be dissolved by the white vinegar and then added to feed water. Then the plants have access to it. If rhe chemistry is off and the vinegar isn't neutralized by the calcium carbonate that is a problem, so just add a little extra calcium carbonate and run through a coffee filter to remove excess solids and it's safe. Never have to buy one of those expensive plastic bottles of water again. I take 40 ml of 20% white vinegar, 200 ml of water, and add in a teaspoon of calcium carbonate. Stir it up, let it bubble fizz and react until it stops about 30 minutes. That's the fun part. Then you strain out the excess calcium. The vinegar is now water. Carbonate evaporated as CO2 gas. Not enough to matter to a plant though. Then I add water to get 5 liters to the concentrate that was made. Put in pinch or quarter teaspoon of Epsom salt. Stir it up and that's it. Money saved, plant happy, less waste. Empowerment.
