I believe Sanderianum is growing in troical southeast Asia, where humidities are always quite high. His statements about the instability of the 'dry' mix may be quite true for his experience, but probably don't match the experience of many more temperate and more arid climate growers.
I do not like making up a stock solution for the Green Care, MSU formulas. To avoid the instability issues of solutions, I prefer to keep my fertilizer in the 'dry' state. (I use quotes recognizing that these dry looking powders have salts with various degrees of hydration).
I do like Ross and some of the others, buy the large bag, and immediately break it down into smaller quantities, taking care to store all in as tightly sealed and as low humidity as practical containers. I use a few 2 lbs screw top polyethylene jars for the small containers. I keep the main part of the bag sealed and inside a sealed bucket to minimize humidity from seeping in. I only open the big bag when I have depleted the small 2 pound cans. Thus limiting the number of times the big bag gets opened & exposed to humidity. I go through about 2 pounds per month, so this works well for me. There are dozens of ways to skin this cat, but basically, Ray's and Ross's suggestions are generally right in line with my experience. I think the MSU formulation is superior to any of other fertilizer formulation I have tried in my 35+ years of growing orchids. I would not let the one posting on Garden Web, nor Sanderianum's comments disuade you from giving the MSU formula a try. There are good suggestions for handling all fertilizers, such as not overstocking, and keeping humidity out of the dry powders. The making of a stock solution is very important for people using proportioners to apply their fertilizers. But if you are making and applying fertilizers directly without using a proportioner, I personally suggest skipping the creation of stock solutions.
Those are my 2 cents. FWIW - Leo
