what is the best way to prevent algae build up in a planted aquarium?

In your case, fast growing low light plants to out-compete the algae for nutrients. With added CO2, a plant friendly substrate and fertilizers, that's your only hope. SOMETHING will use the nutrients, whether it's plants you introduce or algae.

I'd suggest aponogeton bulbs. They're relatively inexpensive, come in several varieties, and grow like mad. A lot of pet sores carry them, even many WalMarts carry some.

Those really small, inexpensive, fast growing "useless" plants are actually the best plants you could use to compete with algae for nutrition. They require low light, and they grow insanely fast.

Other than that, go to a pet shop and see if they have any "pest snails". These are a wide range species range of snails that they don't like to sell because they aren't particularly pretty, but they actually do the BEST job against algae, and have much lower bio load than ANY algae eating fish. You can usually find some laying around in the plant tanks. Malaysian Trumpet Snails also do a good job against algae.

Clean out 25% water changes weekly.

I'd get oto's or cherry shrimp to get rid of algea.