In the wild they are often colonized by ants. Clearly this is not a
desirable condition in a greenhouse. The acidic fertilizer serves as a
substitute for the conditions the ant colony creates, or at least
that's my understanding of the situation.

J. Del Col

That's interesting. I had cymbidium that had its best blooms on it
while ants were living the pot. Afterwards I didn't know whether it
was the acid from the ants, aeration from their activity, or more
organic type fertilizer from their waste.