I have a 2gal. sprayer and put in a tablespoon of each, but I don't spray as often as you do. I'm also spraying about 15 different species of orchids, some that feed much heavier than your Phals, which are slow growers. I just spray my Phals lightly compared to the other types.
The more often you spray, the weaker the solution - but as it gets warmer, your plants can use gradually more, too. It's not a fixed amount.
If your plants are green and healthy and have new leaves by the time the weather gets cool, you will be tapering back to a very light dose by winter.
