I have a 2.5 gallon nano with 30 watts 6500K daylight compact fluorescent 30watts light, Seachem Fert Dosing of different nutrients tapered for 2.5 gallon, regular excel dosing, weekly 20-30% water changes, and DIY Yeast injection. Well I was always critical that these things would keep the tank algae free. Algae(mostly string, Blue Green Algae at one point, diatoms, green dust algae, etc.,) pretty much had their way with this tank for almost a 6 months. Plant growth was not an issue and the plants fluorished, but the tank looked butt ugly because of all the algae. I just persisted in doing what I was doing and the only real change that I made was changing my DIY c02 brew weekly to try and create more consistent c02 levels as per Tom Barr's recommendation. Well, I don't know if the tank matured to the point where a balance was achieved or just changing the DIY C02 brew weekly caused the algae to disappear, or perhaps it was the barley straw extract I began adding with every water change, or a combination of these things. The tank is now 90% algae free. I was waiting for some plant anchors as I really need to rescape the tank due to the heavy jungle like growth. Depending on how the rescaping turns out, I may post pictures.
Now, I am hoping for the same miracle on a 5 gallon hex tank that seems to be over-run with green dust algae and has been for almost 4 months. With the 5 gallon hex I am experimenting with E.I instead of Seachem Fert dosing for comparison purposes, so we'll see how that goes.
Also, my "LostWorld" experimental tank as per my signature still remains 99% algae free and this was the tank that never ended up with a major algae break after 2 months like the other ones, and when I started that tank I was not using c02 injection or even excel. The only real difference between this one and the others is that it has a UV sterilizer and a purigan filter insert. But then, so does my 40 gallon tank, which is totally over-run with all kinds of algae. Go figure.