I tested the run off of my 2 week old FFOF soil last week, memories fuzzy but it was between 500-600 ppm, and the plant’s are healthy.
I use a mix of FFOF FFHF and generic potting soil in 3 gallon pots and my ppm going in was 71 and coming out in runoff was 657.
Make sure you check your water three times. Once before doing anything, after adding nutes (or any additives)and then lastly in your runoff.
I can’t even imagine your tds numbers being that different. If your plant isn’t showing any issues I would let it ride and check it again on your next watering. I would make sure you get somewhere up to about 20-25% runoff. If you check the runoff tds the moment you start getting runoff your numbers will likely be higher. I test the runoff toward the end of the runoff or I collect it and test realizing that the collected water is more likely an average tds and not a tds of the last water out of the plant.
@Swan1234 can you post some updated pics of your plants under natural or white light please so that the guys can take a look at them?
When I used FFOF, I would fill my cloth pots with FFOF and run water thru to get the run-off and check it. I had ppms of 7500 straight out of a new bag! After a 4 gallon flush of fresh water, I was able to get it down to 1000 ppm before I could even plant. Check every bag!
That’s what happened to me @RSgrower
Can you plant seedlings in 0 pm or ppm. Or 0 ec or tds.