Can I get a better bulb?The more important question is what do you plan to grow? But most likely no its not sufficient looks like a t12 you probably are stuck with low low light plants. Mosses, java ferns, anubias, swords, bacopa to name a few. Your also probably going to grow very impatient waiting for new growth.
Sent from my PC36100 using Tapatalk 2
What can I get for around $40?The 20 printed on the bulb means it's 20 watts. The thickness of the tube is a t-8. There are different fluorescent tube sizes. For example t-5, t-8, t-12. That bulb is a standard fluorescent so it's low wattage. There are high output fluorescent fixtures and bulbs which most who have planted tanks on this forum are using. They run double the wattage for the same size bulb but require a ballast and fixture to support it. You couldn't just buy a high output bulb for that fixture it wouldn't be able to power it.
I am not sure what color temperature that bulb is either. It's something you need to take into consideration. Is it more yellow(warm) or blue when you look at it? 20 watts on a 30 gallon gives you .7 watts per gallon. That's very low for plants. You could grow moss and low light plants very slowly. If you want plants I'd invest in a better light honestly.