Tropical Fish Keeping - Aquarium fish care and resources

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smit3183 02-26-2012 09:14 AM

Question on lighting
i have a 55 gallon and just replaced the 32w 48' 8000k full spectrum daylight t8 bulb with an plant and aquarium f40 t12 40w wide spectrum. It says it's designed specially for plant growth. my plants had been growing very slowly. Is this light i got any better? It doesnt look nearly as bright. I also had been leaving lights on only 8 hrs a day and read that 10 may be better if you have live plants. If this light isnt any better what type of light would be recommended? Also it says light output is 1900 lumens

beetlebz 02-26-2012 09:33 AM

welp, Im not sure it was such a necessary upgrade to be honest. The original T8 might have been outside the traditional color spectrum, as most recommend 5500-7000k, but I dont think it was that big of a deal. The 30 watt T8 is actually going to be a little bit brighter than a 40 watt T12. T12 bulbs are not as efficient as T8s. I have 5000k bulbs on my planted tanks right up through 8000k bulbs. The 5000k definitely grow better, but the 8000k are no slouch.

Quantum 02-26-2012 09:55 AM

The issue with lighting is twofold: the amount and the type. As mentioned, the T12 is less effiecient than the T8, so you haven't increased light output even though it is higher watts (though I would argue light output is about the same and the dimmer appearance and low lumen number is due to the different spectral output and not intensity). You have changed the light qualitatively, as the 'plant' bulb will likely emit more blue and red wavelength light (likely has a pinkish hue).

Having said that, you should be able to get good plant growth with either bulb. If not, my guess is something else is going on. How old was the T8 bulb? What do you use for filtration? Use fertilizer? What plants are you trying to grow?

Byron 02-26-2012 01:06 PM

The so-called "plant" and "aquarium" tubes are less intense, plus there is the hue issue because they distort plant and fish colours. I would simply go to a hardware store like Home Depot or Lowe's and get a 6500K 48-inch T8 tube. GE, Phillips and Sylvannia make them, just get the one with 6500K and you're set. I use these, they work very well. And they are less expensive, here in Canada a package of 2 sells for $7.

From my experience with the type of tube you now have, long-term, the plants will not respond as well. The intensity is less, however we measure it.


beetlebz 02-26-2012 06:40 PM

Oh, not to mention running T12s on T8 ballasts and vice versa can cause problems with the ballast long term, in some cases. Just an FYI.

x2 on just getting a daylight bulb from the hardware store. Every one of them is likely to carry them, and they is cheap.

MinaMinaMina 02-27-2012 03:19 AM

Also, with running a T12 lamp on a T8 fixture... since the T12 has a larger diameter and therefore sits closer to the fixture, sometimes the proximity can produce enough heat to warp the housing and/or plastic reflector. Its happened.

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