1.) Before you try CO2, try changing your gravel. Try a new substrate like eco-complete or flourite or even clay cat litter. You can either add it to the gravel you have now or "start" over. Except cat litter, that needs to be added under the rock gravel. If you add it, be sure to rinse it before adding and add it during a ~50% water change so you don't stir up things too much.

You will see much bigger changes in your plants by changing the substrate than by adding CO2 (for most plants). They roots will grow stronger, and you will see more leaves and less wilting. You could also try root tabs, but they are somewhat less effective.

2.) Bubblers are completely unnessary if you have a HOB and have some good surface tension from the return. Bubblers remove CO2 so if you ever go that route, turn them off during the day like James mentioned. From the look of your tank, this should not be a problem.

3.) In a planted tank you really don't need to vacuum the gravel, just change some water weekly. The junk on the bottom act as nutrients for your plants. Just don't let too much food and dying leaves decay. The gravel should still look fairly clean without much mulm build up.

Your bigger leafed plants are a type of sword plant (probably a melon), not anubia.

__________________

--->Pictures of my 75g Amazon tank<----