A few addressed questions, gathered here and there in the thread :

- What is wrong with MSU, 15-5-15 CalMag and similar fertilizers (
very high high NO3/NH3 ratio, if not exclusive) ?

Everyone will tell you those are great, fantastic and so on. Foliar
analysis reveal certain trends with their use. Some micronutrients
decrease, some others increase, and so on. Eventually, after those
micronutrients will be exhausted, the plants will die, no matter what
can be done when the symptoms start to be severe.

Jerry Fisher, from Orchids Limited :

http://www.orchidweb.com/dtl_spk.asp?PRecno=988

He provides advice to partially prevent the problem, by using a lower
NO3/NH4 ratio ( thus lowering the pH, supplying NH4, and temporarily
preventing the need for a quite dangerous and necessary micronutrient
supplementation).

Many other problems can, and will arise because of those "new"
fertilizers, or substrates. It takes a lot of time to visually assess
the problem, but usually when such problems can be visually addresse,
the grower is more or less broke. micronutrient deficiencies and
toxicities, once they have been going on too far, are hard, if not
impossible to correct.

Growers have been using high urea fertilizers with limes for ages,
with no troubles at all. Now, urea is evil, ammonia is too, and
nitrate is the way to go. It might be partially possible to use plain
NO3 fertilizers, but not without foliar analysis, substrate analysis,
pH correction of both the substrate and the irrigation water, and
micronutrients supplementation.

NO3 prevents many bacterial diseases, that can be addressed easily
when using urea, or ammonium fertilizers : test fertilizer solution
and substrate, both pH and EC. Testing fertilizer alone is not enouh.

Preventing loss of the entire collection by fertilizer misuse : US$30
foliar analysis from time to time. Free in certain states or
countries. Monitor from time to time. Comparisons helps to see
problems BEFORE the will arise. 99% of the orchids that die of a
non-obvious conditions have been affected by such deficiencies or
toxicities. "Phragmipedium besseae made easy... " Besseae and its
hybrids have been one of the most proeminent victims from this lack of
interest in foliar analysis... Happy plant, then one specific
micronutrient increase up to a certain level, another one drops.
Watery marks appear on the lower side of the leaves. Plants stops
growing, stops rooting, make multiple tiny shoots, wilt and die. Bye
bye. Lowering the pH is far from enough, to relably grow those
plants...

- CHC has been known to be extremely dificult, dangerous to use.
Everyone knew that in the professionnal pot-plant trade, especially
the special calcium nitrate process ( and no, heavy watering can not
replace the initial calcium nitrate soak). It took 7 years amongst
smaller growers to be discovered as essential. Cost : US$40
destructive analysis.

CHC must be analyzed every other month, to monitor the changes,
especially micronutrient (over)load.

Before getting any advice on fertilizers and substrate, the sole
question to ask is "have you done foliar and substrate analysis on the
long term ?" Others comments are unfortunately worthless and the
source of many myths or short term "magic bullets".