Lighting

[Saltair]

I am sure this question has been asked over and over, but I cant get it straight. Everything I read places its emphasis somewhere else. I have a 16gal tank that takes an 18" 15W bulb. I started with a 5500K light that covered the full spectrum according to the graph on the package. My swords are dying, and I have been made aware that I dont have enough light. I would like to find a two bulb fixture, but not being able to do that quickly, cant find one, I bought a 5000K bulb with higher peaks in the Blue and Red spectrum than I had before. Of course now my tank has a purplish hew. So what is more important? Wattage? K? Spectrum? for the same wattage do I gain any advantage by using a higher K? or a bulb with emphasis on better parts of the spectrum? So confused.

 

[maxst2]

All are important. If you don't have enough light you need to get a bulb that consumes more power...wattage. With that the brighter it will be...making its spectrum brighter etcetc.

 

[FishEggs]

any bulb in the 5000k-10,000k has usable light spectrum for photosythesis. changing the spectrum within that range wont help much at all for that process. you need to add more intensity of that spectrum which means another bulb. i'm guessing the fixture you have just has a piece of white plastic as a reflector. you can put aluminum foil over that to increase the lumens into the tank and it might help some. Amazon swords are also heavy root feeders. what type of substrate are you using and do you use root tab fertalizers? a root tab placed next to the sword might be all you need.

 

[Saltair]

I have been using root tabs and the root structure is good. I tried to pull one out yesterday and was amazed out how the roots had grown. The substrate is small gravel. There seem to be some new shoots, but the existing leaves started to get brown spots, then just turned all brown and died. I guess all that is left is a light problem, maybe CO2? You are right it is just a plastic fixture. Do they make a twin bulb fixture in that small a size?