Quote:
Originally Posted by larrylwill
How much calcium would you suggest. I have some calcium carbonate in pill form 600mg I could desolve in the water. I water with distilled water from a dehumidifier, I use a fertilizer with minerals in it.
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Plants can't absorb the calcium in human supplements. And, to be perfectly frank, orchids aren't going to readily absorb the calcium in eggshells. Hell, they don't even absorb the calcium in most water supplies very well. The best thing to do is to pick up a Ca/Mg supplement this way you know 1) how much you're actually giving and 2) it's the correct form for the plant to easily absorb and utilize.
It isn't expensive and easily picked up at any hydroponics store or on Amazon.
Side note - not all black spots are a sign of calcium deficiency.