The Marineland light would give you very good low light, so that CO2 would not be needed. The others are designed for reef tanks so they would very likely be too much light for a planted tank, and would make the tank look weird with the actinic LEDs.
I've been trying to read through you older posts and it seems that in your opinion a T8 is enough for a 12" deep tank with low light plants. I guess my question to you is, are the marineland T8 fixtures ok, and would you recommend 1 or 2 of them for a 20 long 30"x12"x12". I would also love to get your opinon on bulb choices, I listed several of them in the thread. Thanks in advance if you find the time to help.
When I quit using a drop checker I was using 1.7 dKH standard solution instead of 4 dKH. That would be yellow at around 30 ppm of CO2. When I was doing that I was using DIY CO2, as I am now, and with that you don't need to get too concerned about having too much CO2, but I liked being able to see that I had a significant amount, using 1.7 dKH. All of this was over a year ago, and my memory isn't good enough now to remember all of the details.