AU - Is water only really water only?

Hi all - Giving my first organic auto grow a crack after trying 2 auto Coco canna grows.

Must say, I'm confused about these water only soils. I've been looking at a few brands like Dr greenthumbs turbo dirt, easy as organics, organic gardening solutions and am trying not to get too confused as I'm not sure if these teas, amendments etc are optional.

Anyone know which would be best for an auto grow as a true water only grow without all these teas and extra bits and pieces? Still deciding whether I want to grow in a 3 or 5 gallon pot.

No happy frog or ocean forest where you live? Roots organic?
If your in Canada Gaia green makes living soil, I like it better than fox farm soils
These soils will feed your plant 1-2 months depending on size of your plant I think
Additionally top dress in flower for better results
I don't do autos so it might be different for them

Everything is Optional!

If you use a "water only" soil, it will be loaded up with nutrients. So you won't need amendments or teas. It will feed your plant. The issue is that your plant will grow big and healthy in that fertile soil. After awhile it will consume all the nutrients in your pot.

To get around this, you could use a big-ass pot, with tons of soil to hold lots of "food" and feed your plant all the way through. Probably bigger than 5 gallons.

Or you could use smaller pots and sprinkle some Dry Amendments on top to feed your plant, after you use up the "food" in the water only soil.

Another way to feed is by soaking a smaller amount of the amendment stuff in water then dumping it on.

As for the best water only soil, what's available is AU?