| | Re: Plant Deficiency Diagram
CO2 is essential to so many compounds that a lack of it causes multiple issues throughout the plant. Look at chlorophyll; by atomic weight it's mostly carbon, by atomic ratio it's still around 2/5ths carbon with a lot of the rest being hydrogen (not exactly hard to come by). Even more of the plants rigid structure depends on carbon, so that fails with a CO2 deficiency too. Gradually developing (days or more) leaf transparency with structural failure always points at a lack of CO2 to me.
NPT's get CO2 issues too, some more than others. Every style of planted tank that I have ever seen has the potential. there's a bit more of a tendency towards K+ deficiency in these tanksbecause it's hard to get without dosing, and the substrate/fish food provides plenty of N and P. Within NPT's, the most popular style is of course El natural. With this method CO2 is gotten around because the system works on not disturbing your tank, leaving lots of organics to break down to produce CO2, and keeping light low. There are mid-day breaks worked in that help quite a bit as well. Even so, BBA happens in these tanks which indicates CO2 issues. It's more often a matter of experience than being of any major method, because the principles are all the same, and the methods are all well tested.
Showing CO2 deficiencies as an entire leaf thing is a very good idea.