Sunshine mix or pro mix preparation?

I noticed something odd when watering through sunshine Mix #4. When giving plain water on my first watering, the runoff came out at about +/- 2.0 EC. What is that 2.0 EC comprised of? I didn't think there was any nutrients in these mixes. Is it the lime activating? Does peat moss inherently have an ability to conduct an EC reading?

Trying to make heads or tails about what is in these mixes. What do I need to account for, because I think whatever is in these mixes might be screwing up my grow sometimes.

Thank you for your time and help

not sure what is in there that is giving you 2 EC.... have you calibrated your meter recently?

I am not fond of promix HP I find it finicky for some reason and am always chasing issues
With sunshine 4 I don't have these problems.
To pre- treat my sunshine 4 for a grow cycle, I take an 18 gallon rubbermaid tote, fill it up 3/4 full of dry sunshine 4. Add to that 1/2 cup Dolomite lime (i use dolopril) and a cup to cup n a half of granulated gypsum.
I also find that running PH going in at 6.8 all through veg and first 2 weeks of flower and I also give 2.5ml granulated gypsum per gallon every watering/feeding.

works for me.

I just measured the runoff from my fresh transplants. Mix is 1/2 Sunshine Mix, 1/4 Pro Mix, and 1/4 Fox Farm Ocean forest. My input water was 0.2 EC and runoff was 3.0 + EC...its no wonder my plants go straight into problems with a runoff like that.

Wondering what the hell that could be? I know Ocean Forest can be hot, but it's claimed that the others don't have any fertilizer...yet their initial runoff for me is about 2.0