We are beginning to see the cause of the algae. There is an excess of nutrients, and low lighting.
Nutrients first. Phosphates in NA is unlikely to be the issue here, and when I see the lighting specs plus the other data, I would all but guarantee it. The osmocote likely are releasing nutrients (if memory serves me, these are not aquarium products but intended for terrestrial plants). As I hope I explained previously, excess nutrients like this plus the CO2 in the absence of sufficient light to balance is a recipe for algae.
First, I would stop the CO2 and remove/reduce the osmocote tablets. Then replace the lighting. Here you have three options.
1. LED. If you get a good unit, this will work fine. it will be very expensive (the most expensive of the options), and you will have to get a very good light that is of the correct spectrum for plants. This would probably be my choice over the 2.5 gallon tank.
2. Flurescent tube. This would work fairly well for the 10g and 20g tanks, but in the tank with CO2 you are dealing with more high-tech which means more light. A T5 fixture would provide this, but without the CO2 (the other tanks mentioned presumably) this would be way too much light. A single T8 would work over the 10g or 20g tanks if low-tech or natural method, i.e., no CO2.
3. Incandescent (screw-in bulbs). This in my view may be your best option, at least for the 10g and 20g if low-tech (no CO2). These are the least expensive fixtures, though not always easy to find but as you are in the USA you should be able to track them down. They will take two bulbs, and here the CFL (compact fluorescent) are ideal. Get the "daylight" bulbs with a Kelvin of 6500K. The smallest wattage is 9w (equivalent to 40w of old incandescent), and two of these over the 10g and 20g (without CO2) will be perfect. I have these over my 10g and 20g and the plants thrive. You can increase the intensity with higher wattage, which would help with the tank using CO2 diffusion, though here it might be better to go with T5 to ensure better coverage and intensity. I would want to look into this one more before being firm.
Now to your plant list. You have plants that need high light (and will benefit from CO2), but also plants that willnot do well with this, unless you can plant them in shade. The CO2 will not benefit or harm them, but the light can.
It may help to see what is achievable. The first photo below is my 10g with two 9w CFL 6500K bulbs. There is no CO2, and I use Flourish Comprehensive SUpplement, 1/4 of a teaspoon, once a week. This is not the "prettiest" tank, as it is used to raise my Farlowella fry and the pygmy corys which spawn continually (hence the dry leaves which is excellent infusoria for fry), but it shows the plant growth possible with very little fuss.
The second photo is my 20g, now used to QT new fish. This tank varies a lot as I remove plants when they get too thick, and this tank can sit without fish for months. Same lighting as over the 10g, and same nutrient supplementation except 1/2 teaspoon once weekly.
Byron.