How-, and how often do you water now?

For a 20%N formula, a teaspoon per gallon is roughly 265 ppm N, and your total solids content is probably around 1500 ppm, which is WAY more than an orchid should ever see. Terp's recommendation of 1/4 tsp/gal would be about 65-70 ppm N, and far more appropriate for weekly feeding.

Fertilizer is cheap - mix it up, pour it through - about a quart per 5"-6" pot seems fine - and let it drain. If you want the bark to absorb more, wait 30 minutes and repeat that treatment. After you do that one- or two weeks in a row, it'll stay open enough that a single drench will wet it sufficiently.