Effect of Changing Bulb Temp - The Planted Tank Forum
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post #1 of 4 (permalink) Old 03-29-2004, 03:51 PM Thread Starter
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Location: St Charles, MO
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I currently have a 5300K, 55W bulb with a CRI of 91 (Philips PL-L 55W/950/4P). When I made the change from a standard 20W fluroescent bulb, the condition of my 29-gallon tank changed considerably. Not only did the plants begin to grow as I expected, the algae also enjoyed the new found light. Since then I have managed to get the water parameters where plant growth is good without algae being a nuisance. I don't want to lose this balance.

My supplier does not sell this bulb anymore. My options are a 5000K or a 6700K bulb, both with a CRI slightly better than 80. I would expect the 5000K bulb to give a bit more of a sunset look while the 6700K may look more like noontime. My concern is how this change could effect the balance in my tank?

Other than a change in appearance, has anybody ever noticed a change in their tank conditions when you change the CRI or bulb temperature?

1.9 watts/gallon
pH = 7.2 to 6.6 (high-pressure, manual CO2)
kH = 2 - 3
Nitrate <= 10 mg/L (AP test)
Ammonium = 0.5 to 1.0 mg/L in my tap water due to chloramine
Fertilizer = AP substrate and fish food, i.e., whatever comes out of the fish
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post #2 of 4 (permalink) Old 03-29-2004, 05:47 PM
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Location: Victoria,British Columbia, Canada
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More often then not if you change your bulb to a different make or model any changes in your tanks growth is a factor of the Spectrum of the bulb, not the visible colour temperature (K) or its ability to render colour (CRI).

What bulbs does your supplier carry now?
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post #3 of 4 (permalink) Old 03-30-2004, 08:29 PM Thread Starter
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I just read a note from my supplier that I can get my old bulb, but it's not listed under "bulbs" :shock: Anyway, I'm guessing that all of the bulbs are probably made by Philips. The information I have now to base any decision is the bulb temp and the CRI. I have one LINK showing some measured spectra of various bulbs. Sure would like to find it again and the other link I had that discussed the wavelengths plants favor.

Where do you get spectral dater for aquarium bulbs? Even if you get them, how do you use them?

More Spectra
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post #4 of 4 (permalink) Old 03-30-2004, 09:42 PM
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