01-26-2011, 07:28 PM
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To the first question: Most of us understand that aquatic plants require light in the red and blue colours of the spectrum in order to photosynthesize (grow). Therefore, it should make sense to have lights that are primarily blue and red, and back in the 1980's we used tubes called "Grolux" that were red and blue. Most of the "aqua" or "flora" type tubes are similar. Unfortunately, this creates a very purplish or goulish tone, and it distorts fish and plant colours.
Scientific studies have proven without any question that plants respond best to light between 6000K and 7000K, what many manufacturers term "daylight" tubes. Hagen makes an excellent one called Life-Glo, and in my humble opinion it is without parallel. But it is expensive. "Daylight" tubes from the hardware store with around 6500K are ust as good and look the same; I have both over my dual-tube tanks. These tubes are high in blue and red, but also use green to balance for the closest true rendition of fish and plant colours you can get. If you really like the blue accent though, you can combine one "daylight" with one other tube that is higher in the blue. I have had this for the past 2 years on my 115g and 90g tanks, and it worked reasonably well. However, algae will take advantage as I will explain in my comments on your actinic tubes.
Plants do not grow well under actinic light. Obviously, the main reason is the lack of red which is essential to photosynthesis. But combining them does not work as well either, and algae almost always goes rampant. The reason is that algae, although a plant, can use any light and will, whereas higher plants must have red and blue. Without a balance of red and blue, plants will slow growth or stop altogether [the "law of minimum" issue] and algae is ever ready to step in. With balanced light (and nutrients in balance with each other and the light) plants easily outcompete algae. I have removed my "bluish" tubes and am replacing them with daylight largely for this reason.
Two regular (T8) tubes will be more than adequate over your 58g. My 90g and 115g are 24 inches deep, and each has only two 48-inch T8 tubes, and as you can see from my tank photos the plants are thriving. Having tried T5 Ho for a week last year, I would not recommend T5; the T5 NO (normal output) are not easy tubes to come by, and the T5 HO (high output) is considerably more intense light. One T5 HO is equivalent in output to one and a half T8 tubes of the same type. Two T8 tubes would in my view be better; not so bright (in consideration of the poor fish that mostly occur in dimly lit waters and do not appreciate bright overhead lighting) plus they are available in more types from more manufacturers. The GE, Phillips or Sylvania daylight tubes are only a coule dollars at hardware or home improvement stores, compared to $50+ for T5 (if you can find them).