Fertilizing in s/h culture

[Cheddarbob14]

Just looking for some basic info as my online research is resulting in information overload. Ive been learning the importance of feeding to each specific plants needs, but looking for a baseline to start out with. I've recently changed 7 various orchids to s/h. Here is what I have: RO water, kelpmax, quantum-orchid probiotics, better gro 20-14-13. All orchids recently changed to s/h (within the last 7 days) are in a bright, shaded SE corner of my house, and are on a heated mat. Will hopefully have some proper plastic to help w humidity temporarily tomorrow.

I do not have any sort of tds or ph tester. Should I invest, if so, buy online or big box store?. Do you have the same, or similar fertilizer products? If so, what is your feeding regimen/strength? When you do the "clean flush", do you tip the pot slightly to try and drain the reservoir before flushing?

Thank you in advance for any feedback, much appreciated!