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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.

Jamie    <"\\\><