Soft Rock Phosphate + Epsom = CalMag?

I use Calimagic, works fine but noticed the box of Dr. Earth Soft Rock Phosphate says 2% P and 16% Ca.

These are granules (no dust). I dropped some in a shot glass with RO not expecting it to but they did dissolve. Not instantly, might have been a few hours but they did.

I tested the PH and it was right at 7.0 so it's not sky high like when I tested dolomite.

Curious if this DIY calmag would function as well as Calimagic in soil or if there would be the issue of it not being available to the plants.

tia

imho, no....Ive used epsom and it takes to long to dissolve..sounds like the same thing here. Calimagick for the win

flaxseedoil1000 said:

I use Calimagic, works fine but noticed the box of Dr. Earth Soft Rock Phosphate says 2% P and 16% Ca.

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FWIW: I use gypsum (calcium sulfate) to treat Ca def. It has worked fine for me. It's not terribly soluable either, but enough. I use 1-2g/gal. It has a solubility of 2g/L.

Soft Rock might be useful if you wanted to supplement P. For example, I have switched my source of K with langbeinite (sul-po-mag) to get Mg when needed. Gypsum would give you sulfur, while Soft Rock gives you a little P.

az2000 said:

FWIW: I use gypsum (calcium sulfate) to treat Ca def. It has worked fine for me. It's not terribly soluable either, but enough. I use 1-2g/gal. It has a solubility of 2g/L.

Soft Rock might be useful if you wanted to supplement P. For example, I have switched my source of K with langbeinite (sul-po-mag) to get Mg when needed. Gypsum would give you sulfur, while Soft Rock gives you a little P.

Click to expand...

Gypsum is 98% water INsoluble, so only use it in a soil environment with lots of beneficial bacteria to break it down for the plant.

Epsom salt dissolves fine, just use warm water if you're in a hurry. You know, like your bathtub? This makes it quite suitable for hydroponic use.

For calcium, try calcium nitrate- which of course has available nitrogen as well. It dissolves extremely well in water and is also excellent for hydroponic use.

Or, just continue to pay ten times more for the cool waterbottle.

Thanks all!

Yeah, calimagic works just fine but got curious after I saw that Dr. Earth Soft Rock Phosphate dissolve.

Take care

The Soft rock phosphate is monocalcium phosphate. It works fine in soil or as an amendment in a potting mix where you're using urea based nutrients, but it's not fine in hydroponics. The reason you don't want to mix calcium and phosphates in a concentrated hydroponic mix is specifically because it will precipitate out as calcium phosphate.

For hydroponics, the only suitable form of calcium is calcium nitrate.

Calcium Sulfate (gypsum) is also only suitable for soil and potting mixes for the same reason calcium phosphate is bad in hydro. The reason you don't want to mix calcium and sulfates in concentrated solutions is because they will precipitate out as calcium sulfate. From that it should make sense that calcium sulfate is a no go in hydroponics.

Magnesium sulfate (epsom salts) is a great for both soil and hydro and it's very soluble, but it can't be mixed with calcium nitrate in a concentrated stock solution, or it will precipitate out gypsum, ruining the stock solution.

This is not a DIY yourself thing so I'm moving it to the appropriate place.