Kelly Zytaruk asks about experience with Sigma PhytaMax medias:
P 1056 Orchid Medium with charcoal and banana powder
P 6668 Orchid Maintainance Medium
P 0931 Orchid Maintainance Medium without Charcoal

All three medias contain identical chemistry except:

P1056 is with charcoal and powdered banana. This media should come close to the
results achieved with P6668 + banana. I tried it on one occassion but prefer
to add the banana at my own rate and to set pH with KOH to 5.5 with KOH
(see below).

P6668 Orchid Maintainance Medium with charcoal but without banana powder.
An excellent media for my work and one of my standard replate medias. I also
using Hill's media made for Gallup & Stribling in Santa Barbara, CA.

To P6668 I add one jar for Stage 1 babyfood banana. Stage 1 babyfood is
without the 15 mg. of salt added to most babyfood. I adjust the pH to
5.5 using KOH.  P6668 produces excellent roots on oncidinae which are
shorter but heftier than G&S media (note: do not confuse with G&B).

Growth is less robust than G&S but plants transplant from the bottle very
well with the roots taking right off.

P0931 Orchid Maintainance Medium without Charcoal. If I were to pick a media to
germinate a broad group of orchids on I would use this media at 1/2 strength.
Marilyn Light gave an excellent presentation on seed viability and
germination at the Odont Alliance meeting held concurrently with the
Western Orchid Conference in Vancouver this year. There is evidence
charcoal may inhibit germination in some orchid crosses.

                                       Sincerely,
                                       Bob Hamilton