Runoff EC is too high

Hi. I just checked the runoff of my two plants and one was measuring at 2.8 EC runoff and the other at 4.8 EC runoff. I never fed the plants with nutes yet. I only gave them plain ph'ed water at around 6.4 and for the last 3 waterings I added some bio bizz rootjuice (0.5ml/L, 0.5ml/L, 1ml/L).Plants look healthy so I'm not sure why I'm getting this high EC Runoff. Any ideas/suggestions would be appreciated. Thanks

I wouldn't look far into it to be honest, if the plants are chugging along and healthy.
It's only really reliable using an inert medium and soluble nutrients.

If you haven't been watering until a little waste / runoff each time, then I'd start doing so.
Just a bit of a trickle is enough really, using soil or potting mix.

If you begin to see lockout or deficiency symptoms, then maybe consider it a possibility.

To me it sounds as if there's plenty of nutrient already.
Probably needn't worry about supplementing any for a little while longer.

Thanks. I'm not worrying or stressing about it as they look very healthy. I just can't understand how the EC can be that high when I never even gave them any nutes yet. Seems a bit strange