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Re: Crystals in PMDD
Tom was asking about crystals in his PMDD:
> From: "Tom Brennan" <brennans at ix_netcom.com>
> What is crystallizing out of my PMDD in the refrigerator?
> Mixed with 1/2 liter of water,
> 1 tablespoon chelated trace mix (Homegrown Hydroponics)
> 1 tablespoon MgSO4+7H2O
> 2 tablespoons K2SO4
> 1 tablespoon KNO3 (more or less, depends on nitrate)
Tom, I would suspect the K2SO4. MgSO4 has a high solubility, so
it's probably not that, and the KNO3 has a pretty high solubility of
35.7g/100ml so you're probably safe there. K2SO4 has a maximum
solubility @ 25C of ~12g/100ml, which would be 60g in your 500ml
volume. I weighed two semi-heaping Tlbs of K2SO4 and it came
out to 35g. This is still lower than the max of 60g, but with the
combo of all the MgSO4 and KNO3, the saturation point of your
solution may have been reached. And the first to go is the one with
the lowest solubility, K2SO4. Case in point: When I first started
making my macro solutions, I combined a nearly saturated solution
of CaCl2 and MgSO4 in the SAME graduated cylinder to add them
both at the same time. You should've seen it, the solution instantly
turned white, got nearly solid and was hot to the touch. I had a
time trying to clean out that homemade coral material.
I do believe that between the MgSO4 and the KNO3, there's not a
lot of water left to do the proper dissolving of the K2SO4. I'd cut
back on each or make individual bottles of each. I make 100ml of
nearly saturated solutions of 30%KNO3, 10%K2SO4, 50%CaCl2,
and 50%MgSO4, and dose them as I need them. For me, it's a lot
easier to manipulate my levels. My PMDD has only EDTA and a
mix of microanalytes (Co, Mn, B, Cu, Zn, Fe) and they're at such
low levels nothing could ever crystallize out.
Hope that helps, Tom.