Red Root Floater Redness

[Aubrey]

I have had red root floaters for about 6 months now. They are in an open top rimless tank with a fluval 3.0 on 50% for 12 hours about 6 inches away from them. They have never been red.

Earlier this month I was getting ready to go to a swap and portioned out some to take and trade or give away. I started collecting the week before and left them in cups on top of another aquarium under a fluval 3.0 at 50% for 12 hours but about 8 inches away. I did not go to the swap and I have left them in the cups on top of the aquarium for about 3 weeks now. They are turning quite red.

The lights are the same. Same settings and time periods. I would have thought that the red root floaters closer to the light that have a constant supply of nutrients from the tank inhabitants would be the better looking redder plants, not the ones further away from the light source sitting in stale water for weeks. Why?

[Daniel]

I noticed low light plants in my woods that turn red in low light mentioned that I mentioned in a post previously

I now notice red or reddish brown on the underside of aquatic lilies also. Even duckweed seems to be red on the low light side.

Plants are green because green light is not used in photosynthesis and therefore green gets reflected and make plants appear green to us. But when every photon counts....

 

[Green Thumb Aquariums]

My reddest red root floaters are those that aren't under the best light with the best nutrients. My guess is that it's insufficient nitrogen that brings out the red. However, my healthiest-looking red root floaters are those under the best lights with plenty of nutrients. 

[Aubrey]

Thanks for the insights @Daniel and @Green Thumb Aquariums. My only other thought would be that the ones in the cups have no competition from other plants.

Even the red root floaters in the tank below the cups and beneath a lid are green. This makes me think lighting might be irrelevant and it might have more to do with nutrients or the exhaustion of nutrients. This wasn't an intended experiment, just the result of me being lazy and then noticing a change and variables.