Help with TDS and PPM

[astrumes]

So I have been using Dynagro Orchid pro as the main fertilizer for my orchid collection. I have had good results so far since I started to use a nutrient solution on my plants (after repotting into s/h I only use a weak root solution on my orchids for 1 month) but according to Ray's website, I've been using too little of it in my mix and actually starving my orchids.

I've been looking at the TDS ppm reading, keeping it in the 80-100 range in my Reverse Osmosis water (12ppm). After looking through some posts about nutrition I realized my mistake when I saw the recommendation was for "100-125 ppm N" as opposed to total ppm.

I went back to Ray's site where there is a calculator for how much fertilizer to use based on the Nitrogen ratio of my Dynagro. That calculator suggested using 1.3 tsp per gallon to get the right N ppm.

Since I have been using such a weak solution until now, I decided to take things slowly and only use about half the suggested amt, mixing 1/2 tsp of Dynagro in a gallon of water. I was shocked when I measured the solution at 480-490 ppm. I read Ray's ppm is about 350-475 ppm TDS at every watering (using different fert and water most likely). Mine seems quite high for being at what is supposed to be half strength.

My question then is, is it safe for my orchids? I don't want to burn any roots but I also want to make sure my orchids are getting the nutrients they need.

Should I continue to use my Dynagro at this ppm or would it be safe to use the full dosage as recommended by the website? I would assume that at full strength, my nutrient solution TDS would be closer to or over 1000ppm. That seems high to me but I'm new to semi-hydro growing.

Any input or advice would be welcome. Does anyone use this fertilizer in their setup? If so at what TDS value?