First, they look fine
coco -- i'm using 70/30 too.. .you want to feed evey single irrigation... early on you may want to ramp up from a 1-ish EC to a 1.5ish EC when beyond seedling stage.
if you religiously get 10% runoff, you will not experience buildup of minerals with a properly balanced diet. if you do, it means there's too much of some element in your mix. The excess runoff waste will average it out to the "normal" level each time. (normal being whatever it is you feed.. whether that is a healthy/proper mix you'll find out soon enough.)
so, observe the plant as you go and adjust as necessary, but fertilize evey single irrigaiton with 10% runoff waste... toss it outside or down the drain.. don't let any potted plant sit in waste water. What you learn this run will help start at a better point next run....
Ah, i see it is an autoflower... might top off at 1.3EC (650ppm on "Hanna" equipment scale) with some of those. Be aware that "EC" is apples to apples on TDS pens, but "ppm" may not be based on the euipment you buy / region you live in.
It my be worth your time learning individual nutrient ppms of your mix - N/p/k/ca/mg/s ...
google "manic botanix nutrient ppm calculator" if you want to have greater resolution of what you feed... over time min/max of each will become obvious if you track them, relative to your garden's environment. There will be differences between your garden and the next.. even changing of seasons may impact what you have to feed at a particular time.
i've tracked it for 3 years now. i know exactly what's going on at the slightest hint of a leaf symptom, which is rare to see at this point. it's nearly impossible for me to cause lockout due to too much of one nute. so, when i do see an issue, it is plain and straight-forward as to the cause. stands out like a sore thumb. it is worth it... you dont even have to calculate it every time you change.. just need to know relative range to stick to on concentrations mixed. if you don't change fertilizer products, you don't have to re-calculate once you know that safe range.
can you do this simply by observing and reacting, yes, but it will take longer and more false positives along the way, objectively speaking, but you can reach same results. Great thing about soilless grows is we control everything... bad thing about soilles grows is that we control everything :P no one else to blame but ourselves when plant is not fed well.