Vanda orchid care: getting a spike

[FreelanceFaye]

Alright, who do I sell my soul to? I've had one vanda for well over a year (Robert's Delight) and a second vanda from the same nursery. They live outside in the summer under an umbrella in the Deep South with ample humidity.
And exposed roots. They get dunked in my fish tank for 15-20 minutes every day when the temps are this high. They seem healthy. Great fat spongy green roots, spitting out leaves like no tomorrow, but no spikes.

Recently tried a different fertilizer, "bloom formula" 6-30-30. 1/2 tablespoon in a half gallon bucket. How often did you fertilize to get yours to bloom?