I'm really not even sure if I should be exploring CO2 for my particular setup, but I guess I'll soon find out. The reason I am interested in CO2 is because with my medium light and dosing Excel every other day, I am still developing algae. It is not out of control and my Otos have kept it to a level where it actually looks very nice, but I'm not sure if it's peaked.
I have a T5 10000k day bulb and a T5 Actinic bulb, both at 21 watts each. I also have a single T8 fixture with a 17 watt bulb. The fixtures sit directly on top of the surface of the water (about an inch away). I run them 10 hours a day on my 36" 45 Gallon tank. The tank is moderately, almost on the border of heavily planted.
Other than the Algae, I also thought of exploring CO2 because of my 4 Limnophila Aromatica and my Alternanthera reineckii. I would like the Alternanthera to become as red as it can. As of now, it is brown with a slight tint of red and I've had it for about 6 weeks (However, the under-sides of the leaves are redish purple...). I would like the Limnophila to become the rich purplish color they can become, but these are still pretty new so I should probably give them more time (As of now, the leaves are mostly green with some faded purple coming through).
I have a dosing regimen that includes Nitrogen, Phosphorus, Iron, Potassium, Flourish, and Excel (All liquids). I also have a combination of eco-complete and onyx sand substrate w/ gravel on top. My nitrates are at about 9-10ppm. PH is at 7.6, KH is at 5 or 6, and GH is at 11 or 12. Ammonia and Nitrites are 0.
Basically, I'd like these plants to become very colorful and I'm wondering if there just isn't enough CO2. All the plants I have are healthy and growing as they should, I would just like to bring out the colors of these certain plants. I don't really have much experience with CO2, and I do have a population of fish in the tank, so I wanted to start out slow with a DIY CO2 setup w/ a good glass diffuser, and take it from there (I feel going right to a pressurized system with my level of knowledge could be trouble...plus, I don't have a "high light" setup). Is this a good idea? Do you think there even is a deprivation of CO2? Also, my buffer is decent, but should I worry about a decrease in pH if I do decide to go with CO2? I can afford a decrease, I just don't want it to happen too quickly, for the fishes sake. I have had very good water parameters and everything has stayed very stable since the very beginning and I'd just hate to throw that off.