Don't take this personally, I'm a making a general statement.
I don't really get this obsession of a "water only grow". I understand the desire to have a trouble free grow, but what are you gonna do on the
second grow?
Are you going to tear it up and put it in a tote, then re-emend it and let it cook? Then use that material in another pot for the next grow? That is what most people do when they're growing in
small pots, but why do it in
large pots?
The idea of a large container is to have a living environment that is set up pretty much like nature. You have all your nutrients in your soil and you also have a nutrient layer at the top of the media just like in nature, the plant will take from everything .
You can design your own feeding program with what materials you have on hand and available to you or BAS has several different ones written up that you can use.
The mainstay of this style of growing is top dressing and developing an active top layer. A living cover crop aids in this setup in several ways. It helps maintaining proper moisture level at the top, breaks down the nutrients that you top dress with, provides food for your girl in that of active upper top layer as you trim it back And the roots supply the rest of the pot when you kill it off.
The idea is to create an environment where you can quickly start another grow cycle without tearing things up. You're not depleting the overall fertility in your container. The fertility should actually increase with each successive grow.
Tray2Grow set ups will be my go to production method in the near future. Since they essentially function the same, it's like having a 25 gallon Earthbox. The plant will develop the same root structure with the wicking mat as the Earth box does with the wicking areas. The plant has all that nice clean nutrient free Water to take up and this left to utilize the other nutrients it finds in the top layer as it needs it.
Now Jeremy is not fully utilizing this particular setup to as foolish as far as the ongoing and continuing growing aspect, he is testing lights and a few other things with this particular grow. You did get the idea though.