Can I use my tap water for daily watering and fertilizing?

[itilien]

Hello,
First I want to mention that I don't grow my orchids in what you consider Semi-Hidroponic, but I don't see any better place to ask my question. I grow my plants, mostly pleurothallids, mounted bare root or in live moss in a closed tank that is misted heavily once per day. I use RO water and fertilize from time to time.
I live in a place with a soft water, and I found a document with its parameters, so I was wandering if I can use this water with added fertilizer instead

I measure the water with a TDS meter and it shows me about 55ppm, EC 116 uS/cm

But looking at this table, I cannot see where those 55 are coming from. There are about 10-12 from calcium, 2 from magnesium and 10 from sulfates. This is about half of 50, the rest is mystery.

This TDS is looking between 2-4 times higher then the numbers that Ray states in one of his articles and I don't know if it is a problem:

"Looking at the nutrient solutions that literally rain down on epiphytes in the forest, we find that they typically contain no more than 10-20 ppm total dissolved solids (TDS) at the onset of a rain storm (it’s almost pure water after that), and that the analysis shows it’s nutritionally almost all nitrogen."

But in another one he states that:
"We recommend feeding at 25 ppm N at every watering, using pure water, two or three times per week or more, flooding the plants each time, mimicking what they receive in nature"

He uses his K-Light fertilizer with formula 12-1-1-10Ca-3Mg at 25ppm N, so he has rougly 2 x (12+1+1+10+3) = 54ppm, from which 20 are comming from Ca, and 6 from Mg, so this contradicts a little bit the first statement, especially in the part "almost all nitrogen"

So what do you think, can I use this water daily, and what do I have to add?