Organic dirt is dirt without the additives, additives which you don't want in an aquarium setup. I use "Miracle Grow organic choice" which is free of the unnecessary extras. I made the switch after reading Tom Barr and Diane Walstead work and also because when you break it down scientifically, the "complete" substrates are essentially sand/gravel laced with additives which run out after a short space of time (6-12 months according to the guys over at theplantedtank and walstead) and therefore needs to be replaced or supplemented.
With soil besides being what the plant would be in naturally, the fish poop/mulm is pulled into the soil broken down and recharges it constantly. Replicating what happens in the natural habitat. Therefore you don't need to add anything lol I had a bunch of seachem products like "iron, potassium, florish etc etc and after dirting I realized that buying all those products was like throwing money down the drain and using them a complete waste of time because I haven't used them since. So in short yes, dirt in my opinion would be the best choice you ever made if you're going the planted tank route. Second to none and dirt cheap too lol. A few points if you decided to use it. Don't use it with the additive laced thing you're using now. Soak it overnight or for at least six hours and remove the floaty stuff that rises to the surface. You'd need a depth of about 1.5 inches capped with a 1.5 cap of fine gravel.
When it comes to the diy co2 the single most important thing is finding a recipe that gives you a consistent co2 production. Anything less and your co2 levels will fluctuate. And Fluctuating co2 is/has been the death of many planted aquariums because it's a fertile breeding ground for several types of algae like bba. My recipe: Organic white sugar, brewers yeast, brewers yeast nurishment, and one tea spoon of molasses. But My suggestion is to experiment or to buy a pressurized set up which is much simpler.
My neons are crazy and breed at least once a day. they're about 3 inches in size. My ph is between 7-8.
This is what dirt did to my aquarium 2 months after. Check out the lotus and you'll see why I dirt aquariums is something I'm happy to help with lol