How to dose MSU well water fertilizer

[sine__nomine]

Good morning everyone!
I have a phalaenopsis. I recently learned about water hardness being important for learning how to fertilize orchids. I measured my tap water hardness using a titrant and got 15°f (french degress). For what I could understand it's considered hard water so I decided to ditch my current fertilizer with which I never saw results (it was 3-4-5, never really saw any growth on my orchid), and buy the MSU fertilizer for well water/hard tap water 19-4-23.

Should I just follow the instructions on the label (1 teaspoon per gallon of water) or are there better approaches? Cause I've read around things about Nitrogen being the most important to dose correctly and 125 ppm being a good amount, but to be honest my math skills are terrible and I don't really know what it means or how to measure it.

Explain like I'm five if possible, thanks a lot!

Edit: I keep my orchid in a vase full of only bark, and usually water my orchid by submerging it in another vase where I dilute the fertilizer for around 10 minutes. Felt like it was important to specify. I decide when to water it by weighing it every morning, if it's weight decreased less than 3g from the day before I water it.