Wow! I should add Slippertalk to my regular reading routine!
There are SO many different subjects in that thread, it's hard to address them all.
The new PrimeAgra wicks better than the old primarily due to the more regular surface, which creates better contact area.
The more uniform size and shape results in more air flow, so that does, indeed, result in greater evaporation. I do not water daily (especially this time of year), but my greenhouse humidity is pretty good, so the surface of the medium in my pots is likely to stay more moist, keeping the nutrients in solution where they can be absorbed by the plants, and making the mineral content less saturated.
The new PrimeAgra does NOT have more of a wet film at the surface than the old stuff. It's actually probably less the case, as the old stuff had some highly densified areas at the surface that could get wet and not absorb the water. The new stuff absorbs and releases much more thoroughly.
That difference in absorption/release properties may be contributing to the observed surface mineral buildup, as by contrast, more minerals were "trapped" in the old stuff, which I guess could lead to chemistry issues over time. The improved wicking can also contribute, as was noted in the thread. The initial free mineral content from the manufacturing process is also probably higher in the new material, but probably releases better. I still rinse the crap out of it before use - and always have.
I have mixed the old and the new, with no issues.
I've been using the new PrimeAgra for a couple of years now, and have not noticed a mortality rate any different than with the old. I believe I have, on the other hand noticed better growth and blooming, presumably due to better - and more stable - water and nutrient availability.
Some responses to sub-threads:
RO water SHOULD, if your system is working right, give you at-most single-digit dissolved solids. The capacity of the system is irrelevant, as the components are different to accommodate that.
TDS meters are notoriously inaccurate, as they are really just electrical conductivity (EC) meters that have a built-in conversion factor that displays the output in parts per million (ppm) of total dissolved solids (TDS). The trouble is that the relationship between the conductivity of a solution and its content varies not only by the concentration of the dissolved ions, but is also based upon the charge and mobility of the dissolved ionic species. That means that in our case, the "standard" conversion factor cannot be standard at all, and actually varies with the fertilizer and water supply. I have an article about that on my "Free Info" page.
Calculating the TDS of the MSU fertilizer in RO, at 150 ppm N, your meter should see something in the neighborhood of 425 ppm TDS. My two meters gave me about 600 and 750.
There's a LOT more to good culture than just the medium used, and one must observe and adjust accordingly as something changes. Even under the worst conditions, I have never heard of anyone killing an otherwise healthy plant in a week. I'd almost bet that submerging a pot in water for a week wouldn't have that quick of a kill.
I always respond to emails I get, assuming they have a subject line that is intelligible and pertinent, or from someone I know. Blake posted some pretty nasty commentary about me both at Orchidboard and Slippertalk, and I honestly do not recall getting any emails from him on the subject. Ignoring things like that is simply not my way. I'm truly sorry that the communication disconnect happened (and no doubt soured him on my apparent attitude), as I would have liked to investigate the situation with him, both to try to fix the problem and and to potentially learn more myself!
As someone stated, so far Blake has been the only one that has expressed problems with the new material, but do keep in mind that folks can express discontent not only with their mouths, but with their feet as well, and just not buy the stuff. Based upon the rate at which it is moving out of my warehouse and the emails I get on the subject, there does not appear to be a widespread problem.
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