8000ppm runoff in soil. Plants look fine though right?

Was reading the other day, electrical conductivity and basically the way most TDS meters work is inaccurate for plants because in growing we are counting the Total Dissolved Solids but the meters are measuring via Electrical Conductivity which renders them useless for example Silica is not conductive but Copper is highly conductive so if you have a wee bit extra copper or iron you see a huge number while the silica goes uncounted ...

I had a similiar problem once but my soil was regular gardening/potting soil which had slow release fertilizer in form of small green balls in it. At the start it releases a bit too much and drags the pH down but 8000ppm is nuts! Sure your meter was reading right? Did you test the runoff some days afterwards? What soil are you using? How much runoff did you produce?

I haven't calibrated. But I have a tds meter I used as a reference on my tap water. Same reading. I think that they would definitely be dead at 8k ppm. Its very strange. Maybe my ppm meter is picking up something it shouldn't be picking up normally because it has come through the soil. Idk but realistically my runoff cant be 8k. My runoff PH wasnt really out so it cant be as you said my plants would be dead

Plants look ok but at 8000 ppm 16000ec they should be clawing up and dying. If your sure your ec reader is ok then I wouldn't be adding anymore feed to it. You have calibrated your reader I take it? Watch for tip burn and leaf clawing. Flush if so, till you get the nutes lowered. Cheers

So just to let you know how I've watered... Soaked the soil with around 2L (plain ph'd). Left for 24 hours. Then put seed in. 10 days later it felt light so gave 800ml at about 350ppm (90ppm after filter) as I thought I could see cal mag deficiency coming on serated tips. Then I watered 2L today with at 350ppm (7ppm out of the filter)

Lights just come on so they are a little sleepy in this photo.