Rob - when you say you use liquid orchid feed, do you mean fertilizer or food. There is a difference between the 2. Orchid food is like a multivitamin for the plant supplying it with trace minerals and nutrients. Fertilizer is composed of Nitrogen, Phosphorous and Potassium in varying percentages.
Check out Firstray's site for more information by clicking this link -
Fertilizers & Plant Nutrition
Good luck
