I have a 20 long that's lighty planted at the moment but will eventually be heavily planted. It currently houses shrimp, snails and a few cories. I'm still learning about proper lighting and was wondering what would be the best kind of bulb to go with. I was also trying to avoid spending $20 or for the bulb so if there is a cheap alternative that would be great too. I'm also trying to promote algae growth so all those inverts will have something nice to snack on.