Less light is better?

[aqua_chem]

Great advice, what I've been looking for. That being said, does algae reacts to the same spectrum as plants?

Most algae use the same main pigments as plants for photosynthesis, so they harvest essentially the same frequencies of light as plants do. Now, that being said, some algae, particularly red algae, have slightly different accessory pigments (or said accessory pigments in greater proportions) such that they can better utilize bluer light than full spectrum light. I believe the last study I read about this was studying saltwater diatoms specifically. This isn't to say that "bluer light promotes algae", as plants are also excellent at using blue light, but rather that algae may 'see' more light in blue-heavy light than they would in full spectrum.


I would like to emphasize two points. One, blue light probably doesn't 'promote' some algae per se, but rather makes your lights seem brighter than they actually are for the purpose of algae prevention. Two, plants use blue light extremely well as well.

 

[Old Scales]

Good information. Thanks Aqua.

 

[skyedale]

This thread couldn't have come at a better time. I was thinking of upgrading my lighting from a 2 tube T5 to a 4 tube T5. I wanted to get some higher light plants and add more plant diversity to my 75 gl community tank. The two tube T5 uses a 54W rosete 650 NM tube and a 54W 6,000K tube. I also have a single bulb 34W 4,000K that I leave on in the evenings.
The plants in my 75 gl community tank are doing great with the current lighting. The plants consist of swords, java ferns, cryp's anubias, duck weed, bolbitis and some sort of red tinged hygrophile that I prune back weekly. I also have some “weeping” moss that started as a very tiny patch that has spread nicely on the drift wood. I don’t have a CO2 system and I haven’t fertilized in ages.
Given that I would have to cut the amount of time the lights are from the current 8-10 hours to 4-6 hours with a 4 lamp T5 setup I think I will stay with what I have. My 75 gl is in one of the small bedrooms that is now set up to be my "girl cave". Yes girls need “caves” too. As someone pointed out, why have a nicely planted tank when you can’t leave the lights on to see it.