I have a question about actinic lights in a planted tank. I know actinic lights don't help the plants out, but what effect does it have on possible algae growth and total wattage? Let me explain. I am setting up my 5th aquarium. Two existing tanks are semi-low tech - about 1wpg of low output T5 with filters. The other two tanks are Walstad setups with soil substrate and no filtration. The latest setup is a 46 bowfront I acquired and I am planning on another Walstad type setup. The light fixture I ended up with is a 2x21w low output T5, but it is a saltwater fixture so it came with one actinic bulb. I have plenty of replacement bulbs that can go in there in the 6500K-10000K range if I want to. What I am curious about is this - with one bulb in the spectrum for plant growth, what effect will the actinic bulb have? The color of the bulb - very blue - provides some cool colors. If the actinic bulb isn't doing anything for the plants, will in encourage algae growth, or is the color temp of the bulb out of the range that even matters in freshwater? In other words, does it even count in the light intensity/wattage equation or is it just blue eye candy? Just curious if anyone has an opinion or experience with an actinic bulb over a freshwater planted tank.