i have 2 10W LED Floods and 2 20W LED Floods (to be tested).
The 10w are a great inexpensive lighting option for shallow tanks like a 5.5g, 10g or 15g but be aware:
- Floaters should not be used as it will cast wide shadowing due to the single point light source
- Lamps are best used through a versa top for maximum intensity. Hanging them 2-3 inches above the tank will diffuse the light intensity significantly on the 10w. It will be noticible as you lift the lamp fixture above the tank.
- Lamps generally are the most efficient without any sort of cover. this works to keep the fixture cool through air circulation but also to provide the brightest light down to the substrate.
The specs on the 20W lamps are significantly greater than the 10W but i have yet to personally wire it up. I intend to keep the 10W on my 5 and 10 gallon tanks but would go with multiple 20W or 30W for the larger tanks.