Bulb question

[TheZoo]

If you like the look, then it will work. What's important is that the light provide enough wattage for the plants, not the kelvin rating.

embarrased to ask, but how much is enough wattage?

 

[phanmc]

For a 10g tank growing anacharis and hornwort, anywhere between 15w-30w is optimal.

For a 20g tank growing amazon swords, 35w-50w.

Gravel will play a part in how bright the tank looks, which is why alot of people use dark colored gravel so the light doesn't get reflected, saturating the whole tank. Added to the fact that the 10 tank usually is slightly less deep as a 20g and the light has less distance to travel before it is reflected compared to the 20g.