No reason to apologize! But all of this extra info helps us help you.
The basics of planted tanks is rather simple. You have plants, light (and think about intensity on the substrate level - not just high output bulbs), CO2 and ferts.
Ideally, you want your plant growth to match up with the amount of CO2 and ferts. The closest things to an anchor to all of this are:
1. Plant selection
2. Light selection
Plant selection should drive the amount of light you need and that should help determine how much ferting and CO2 you need.
Planted tanks typically overdose on ferts (in the water column) bc unlike terrestrial plants, changing the water out effectively removes all excess ferts.
So plants melting:
This can happen bc the plants were rehomed from another tank (LFS, or friend's) and water conditions are typically different from tank to tank. This is usually temporary so as long as light, CO2 and fert parameters are relatively equal.
The other reason is bc the plants are starving. This can happen if there is too little light or too much light. Clearly, thats easy to tell at the fringes - when you have way too little light vs. way too much. For those cases in between, you should look at the plants closely. Are the leaves or parts of the leaves closer to the light showing damage first? If so then its likely too much light. If your plants tend to reach for the top of tank (and by that i mean they're stringy and grow more vertically than horizontally) then its likely too little light.
Too much light means that either your plants aren't designed for that light, or that the plants need more food to grow with the light they're "ingesting". Plants need an appropriate amount of light, CO2 and ferts. If light especially is out of whack with the CO2 and ferts, then you can endager your plants health (partly why its the closest thing to an anchor). Too much CO2 wont hurt the plants - but possibly your fish and too many ferts wont hurt the plants but possibly your fish and the chances of getting algae.
The plants you have, as far as I can see, are not that demanding on light. Looking at what you're doing, its likely that the light is the deficiency here and you need to upgrade to something slightly better. It could also be that some of your plants are not either designed for the environment and its also likely that some just won't grow regardless of everything "looking good on paper".
I would start by making sure no plants are being overshadowed. I would also leave the light on longer (but not more than 9 hours a day). See what growth you get and keep your ferts up. If you get algae, then its a sign that you are adding too many ferts + too much light for your plants to consume and you should decrease both.
Play it like that and come back with results and we'll help you fine tune this.
Oh, and although I hope we havent irrevocably damaged this thread, start another thread so we don't completely kill this one (sorry to the rest of you)!