Originally Posted by ChunkBunny
Thank you for the reply. After reading that sticky post again, it makes a little more sense to me. From what I understand, one 6500K T5 bulb would be sufficient, is this correct? If so, will that fixture still work for me? It is the best priced fixture I have found.
Also, to clarify, when you say those bulbs included with the fixture are too much, do you mean to Kelvin rating? I did see that they were 10,000K.
I'm really struggling to get this stuff through my head.
If that fixture will allow one tube to be removed and the remaining tube still light, it will work. But if you need both tubes in to light, it will be too much intensity. And there is no way to get around intensity, such as by reducing the duration. While the light is on, the full intensity is going into the tank, and this is bound to cause algae to proliferate. Plants can only use the light if all the necessary nutrients are available to them. And unless you invest in CO2 diffusion and then dose nutrients daily, this will not balance.
The Kelvin is also an issue but a different one. Kelvin is just the colour temperature of light, as we perceive it. Sun at mid-day is around 5500K (going from memory here, but it is something around 5500K). Lower numbers are "warmer" (more red/orange, less blue) and higher numbers are "cooler" (more blue, less red). Plants do best around 6500K which has sufficient red and blue plus some green/yellow for a natural rendition of colours. As long as one tube is around 6000K-7000K, the second could be higher. This would give a crisper cooler "white" to the tank. However, the intensity of this light is too great and that is the major issue, though both tubes being so high in Kelvin would also cause issues for plants. Light this high in K is aimed at marine tanks where corals need such blue white light. And the intensity is due to this too, as T5 was designed to provide more light intensity with fewer tubes than what the T8 provide, and this was important for marine tanks that need this higher intensity and bluer light for live corals.
So, if one tube alone will work--and this depends upon the ballast manufacture, but at this low a price I would not expect this feature as it is more expensive to have--and with different tubes, fine. Otherwise, I would not recommend it.
I just did a quick look at Drs. Foster&Smith online site and they have single and dual tube T8 fixtures here: Fluorescent Aquarium Lighting: Marineland Fluorescent Lights
I would suggest the dual fixture as it will give you more o[options for plants. The single will work, I had one years ago over a 55g, but it does limit plant options more.
Single T5 fixtures are next to impossible to find. This site has none. Reason I suspect is that T5 as i mentioned above was designed for more light intensity, and as a single tube would be in between a single and dual T8, no one is going to pay more for T5 when they can pay less for T8. T5 fixtures and tubes are still more expensive than T8. But over natural planted tanks, T8 is still about the best. The very new LED lighting might overtake it one day but this has not happened yet.