12-21-2009, 03:15 PM
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Some comments in response to the last couple of posts.
First, I have 80 watts on each of my 115g, 90g and 70g tanks; when I had a 55g I had 40 watts but today I would go with two regular tubes (80 watts) or one T5 HO on a 55g.
On the T5 HO tubes, bear in mind that these are approximately 1.5 times more intense (brighter) that regular T8 tubes. In other words, two T5 HO tubes will be more light than three regular tubes of the same length. The wattage when talking T5 HO is not the same as wattage of regular tubes. Which is why I suggest either two regular tubes or one T5 HO tube. And even though the one T5 HO will be less wattage than the dual regular, the light will be the same or slightly more intense. T5 HO really is very intense light. I know it is only my opinion, but having tried one of these for a full week on my 115g which is twice the size as your 55g, the dual T5 HO was just too much light. I jokingly commented that my poor fish would be asking me for sunglasses.
And that brings me to another significant point about light that hasn't been mentioned in this thread yet--the fish. Most of the fish we maintain in planted aquaria are forest fish from the jungles of South America and SE Asia, and less often West Central Africa. These fish inhabit slow streams and creeks and flooded forest that is almost always sheltered by overhanging vegetation. Direct sunlight rarely gets through the water. It is no surprise that these streams frequently have little if any aquatic plants because they have too little light. The Rio Negro and Rio Guapore in the Amazon basin are exceptions, they have very thick aquatic plant life, but the direct sunlight is still minimal. And this affects the fish and the plants.
The fish are programmed by nature to inhabit dimly-lit waters, and many believe this explains some of the vibrant colourings of fish like the neon and cardinal tetras; the neon line shines in water so dark you can't see the outline of the fish itself, only this flash of colour. But the point here is that to be relaxed and comfortable in their aquarium, these fish need dim lighting; over a dark substrate and with a dark background their colours are vibrant and spectacular. And a fish that is less stressed by its environment will be healthier and live a normal rather than a shortened life.
And to the plants, as Diana Walstad points out in her excellent book Ecology of the Planted Aquarium, aquatic plants have a very low light requirement, much less than what some would have you believe. Less than one watt of full spectrum light is adequate for the vast majority of aquarium plants. Growth will be slower than it will if you increase the light and pump CO2 into the tank, but the slower growth will be no less beautiful and healthy.
My thinking always has been to provide the most authentic environment we can for the fish and plants in our aquaria. This has two results. The aquarium will be more stable without constant fussing and intervention by the aquarist. And this means the fish (and plants) will be healthier and more likely to display natural behaviours and colours.
So, back to the light. You may be tired of seeing it, but there is a delicate balance to a successful aquarium between the fish, plants, light and nutrients. Algae is rarely seen in a balanced setup, simply because the plants use the nutrients which do not exceed the available light and these are not greater than the available carbon from CO2 produced by the fish. Adding brighter light will not result in better plant growth if the nutrients (including carbon and nitrogen from the fish) are not in balance. The absolute first thing to determine is the fish load in the aquarium; then select the light that balances, and suitable plants for that combination; lastly add the missing mineral nutrients in balance with the light and carbon. There is some experimenting in this, but there are also some tried and true formulae that work. One watt per gallon of regular full spectrum light works with the usual fish load and plants. Weekly liquid fertilizer that supplies the missing minerals is usually required. That's it.