I think provided you get the right dilution rate it would be fine, that might be different for orchids than for bromeliads (I don't know).
There are various views on fertilisation rates for orchids, but if it's Phals then you won't go wrong with using the calculator on this link.
Fertilizer Mixing Calculators
Ray who made the calculator now uses a lower rate however the rate given by this calculator isn't too high for most orchids provided you flush regularly. (I currently fertilise based on the results from this calculator).