Growth Technology's easy to use one part nutrient. Simple: one bottle called 'Ionic Grow' and one called 'Ionic Bloom'.
Ionic contains all the same essential ingredients that constitute a more typical AB two part nutrient but are diluted down to a point that they happily sit together in solution. For small gardens, or when needing to make just a small volume of nutrient solutions using a one part nutrient is easier and allows for larger margins of human error.
Orchids have very specific nutritional requirements and, although it is true that they can survive on very low levels of nutrition, they will only reach their full magnificence if properly fed. Just ask a professional grower or a consistent winner at orchid shows.
Orchid Focus Grow and Orchid Focus Bloom are available in one-part formulations.