Rick, I don't understand your last statement. What does that mean???
All the organic media we typically use, dead sphag, bark, CHC or coir, peat, will preferentially absorb mono valent cations (Na and K) and give up divalent cations (Mg/Ca).
All of these natural plant/wood products have all of the NPK Ca/Mg in them already and as they break down will give these up. But the pores in these materials (that we prize as water holding systems like sponges) are charged to the point they also retain/exchange nutrients.
You may remember some of the old conversations from the Wellingtons about conditioning CHC with calcium nitrate and mag sulfate to drive out the Na/K retained in the pores. Actually it takes strong concentrations of Ca/Mg to drive out relatively weak concentrations of K since the affinity for the monovalents is so high. However, the system is easily reversible without consistent and high availabiltiy of Ca/Mg in the potting mix or irrigation water.
So every time you fertilize a little bit goes to the plants and a lot goes into the pores in the potting mix. The organic constituents preferentially(as do the plants themselves) keep the K and let the Ca/Mg pass through. So over time you end up with very high concentration of K in the plants and potting mixes. If you preload your mix with Ca/Mg (or "infuse the chips with Ca/Mg as for Orchiata) you can stretch the life of the mix with even fairly high K fertilizers. If you reduce the amount of K going to the plant and mix in the first place, you could probably run a mix to complete physical breakdown and still have the plants do good. How many orchids (let alone paphs) can you think of that have roots completely exposed to air? Stuck to the sides of trees or limestone cliffs (also note that limestones contain almost no K, so where do all those calciolus paphs get their K)? Remember some of the insitu pics of P sukhakulii growing on rotten logs? That's a dense material around those roots, but if that was in a pot we'd claim that it would die of root suffocation from a broken down mix.
I guess just about everyone growing orchids in some type of organic media has observed "mix going bad, breaking down, going sour, salt build up........." and always looking for the "ultimate mix". The salt build up argument cracks me up when we look at species like exul and niveum that get spayed by ocean waves. That's a ton of salt compared to anything we water with, BUT these plants are growing on potassium free limestone, and getting watered, not only by rain, but by ocean water that inherently has several times more Mg and Ca than K.
I have observed a commonality in all these symptoms of bad mix and fertilizing which relates back to excess K. It's kind of funny at this point since I've left a handful of paphs in old bark mixes, that a making new big gains in the same old rotten mix, and I've done this by getting the K way down and boosting Ca/Mg.
I used to have pretty poor longterm luck with adult Barbata types and paph seedlings in general in CHC. So I'm experimenting with a handfull of seedlings Barbata and Multis in CHC with the reduced K diet.
why should it? Plant & media would be defying gravity! Do you wet the media or plant dry? If dry, I could see it being light it would float. I got some Orchidata from Ray when he offered his special, it's hard to describe, not what I expected, not as dry as Rexius but it's not moist either, I don't see where it's going to be any problem.
