Ah, yes, I observe the same thing. But does that mean that we "want" roots growing into the perlite? And by that I mean, are you observing any significant differences in those tomatoes? I did not observe any significant differences when growing in perlite hempy tubs vs coir, other than the pH and Ca and Mg issues I mentioned previously.
I have a media I feel out preforms all others I've used. I have used straight Rockwoll(6" cubes stuck in slabs), RWflock mixed with LECA, str8 LECA, diatomaceous rock str8, peat moss "soil" with perlite (big n chunky), coco with perlite, a mix of the two, coco st8... for a couple good years I made a coco based mix from seperatly sourced ingredients very similar to the "Just Right Xtra" pre mixed bags from GH except I used more maidenwell Diatomaceous Rock(DR)than they did, twice as much... Etc. etc....I now do something specific that works for me, but is centralized around what I call the mixture. It's just medium sized diatomaceous rock and coco croutons (coco chips). About 50/50. The croutons are the same material as the coir, same CEC, just much more in spaces and drainage. I irrigate 3x a day so they are Lil sponges. Tha DR holds nutrient solution or water(same shit right ;)) just as well, and has great capillary action, but dries faster. To nerd out further, the the air spaces in the media-, which DO comprise a certain amount of volume percentage, as pointed out by someone above, -are probably near 100% humidity. The root hairs are unimpeded in their growth in these areas, coupled with their extended reach from colonizing mycorrhiza, means MUCH more access to nutrients all day and much more % in successful survival of the root hairs past a few hours, turning into faster lateral root growth. So I don't believe that the air space is wasted in aerated mediums if the environment is well controlled. Which is the job of the CEA operator. It CREATES a situation of greater control if you want to keep the water moving. At least it has for me. I like the available silica in the DR as opposed to the perlite, and it holds my plants in place much better. The chips over the coir because I have better drainage. I do put a small 2" or so bed of coir with Glomus intraradices mixed in directly under the cutting or seedling. But hen top up with the mixture. I got tired or fingerings or pushing around my pots. And hand watering. And slow(er) veg.
Were you watering them the same?
yes, they both established substantial root zones very quickly.
I am a Hempy Coco grower