first go around I wasn't trying for yield so i flowered them very small was just trying as many seeds as possible so it wasn't much. But this time i veged for a few weeks and they are a decent size but they are only a couple weeks into flower, if i had to guess id say 3/4 - 1 oz , but who knows, the ones in the two gallon plastic pots got a extra week or two of veg have a nice thick stem
Those pieces are huge. I'd try to break them up with a hammer if you wanna use them. That's all my hydro store had too, so I ordered mine from BAS. I got the small black lava rock and both sizes of pumice. The lava rock is a lot heavier than the pumice and a little more expensive. I also added some BioChar.
I'm a few months into this combo, so far so good 
Indeed, and at that point the breakdown of the org. fertilizer stops in these regions. And existing roots will die after some time, so these pots are good for veg to train a more fully rootball - but for flower not optimal. In an organic growth, esp. when you water from hand, a closed pot is better for several reasons:
It's the minimum size for notil to support microbial life indefinitely. You don't have to ever disturb the soil just dig a hole next to your last stump and you're good to go.
Thank you for explaining the reason for pot size, much appreciated.
Well, I will remember that for next go around I am in organic and used fabric pots, going ok now..but still.