Is the lighting for the 20L?
Those stores usually carry Aquarium and Plant grow florescent bulbs. They're cheaper that lfs.
If it's for a bigger tank and you have a glass top on your tank, you can use the cheap 2 bulb shop lights w/reflectors. I've put mylar on the reflectors for better light output, but it's not necessary.
Glass does stop some of the light spectrum, but you have to balance that eith fixture cost. To do without a glass top you have to use special sealed fixture ends.
If your growing coral/live rock, that's a whole different story. You need an incredible amount of light.
Those stores usually carry Aquarium and Plant grow florescent bulbs. They're cheaper that lfs.
If it's for a bigger tank and you have a glass top on your tank, you can use the cheap 2 bulb shop lights w/reflectors. I've put mylar on the reflectors for better light output, but it's not necessary.
Glass does stop some of the light spectrum, but you have to balance that eith fixture cost. To do without a glass top you have to use special sealed fixture ends.
If your growing coral/live rock, that's a whole different story. You need an incredible amount of light.