Tropical Fish Keeping - Aquarium fish care and resources

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Follow It Home 09-04-2007 09:32 AM

Light bulb
Hello again everyone, I realize how annoying I am getting but I have a question about the lightbulb that is going to come with my new fixture. I comes with a 10000k daylight/ 460 actinic bulb. now from my understanding this is more directed at a marine aquarium, but would be let my plants grow? should I got grab a 6700k daylight bulb?

jones57742 09-04-2007 10:25 AM


I have a 30" deep freshwater tank and two fixtures with two bulbs per fixture.

I currently have three 10000K bulbs and one Dual Actinic 420/460 in the fixtures.

I experimented with several configurations and determined that the configuration cited above was the most beneficial for plant growth.

Although not well documented in the literature and evening conflicting information exists in the literature I believe that the addition of some blue light to the white light enhances the rate at which the light is absorbed by the chlorophyll and therefore the rate at which carbohydrates are synthesized.

I tried 6700K bulbs (these are typically marketed as plant grow light, daylight, etc.) and they would not produce enough light to allow plant growth at the bottom of the tank.

Follow It Home 09-04-2007 12:52 PM

great news! I dont have to just chuck a brand new bulb. Thanks jones! your knowledge astounds me yet again :-)

mgamer20o0 09-04-2007 01:01 PM

what kind of bulb? yes the actinic bulb is going to help but not as much as one for 6500k-10000k bulbs. i would switch it out.

jones57742 09-04-2007 04:30 PM


All that I can say here is that the lighting scheme which I described in my previous post qualitatively seems to be the most beneficial for plants.

Also please note that this lighting scheme also seems to enhance the colors of the fish significantly more than the other schemes which "I experimented with" (this assertion is qualitative also).


If you have experience with the the above cited lighting scheme and another lighting scheme that you feel is more beneficial pls advise and I will probably try it.

I know that what I have said above does make any sense whatsoever with respect to theory!


fish_4_all 09-04-2007 04:44 PM

First, I have missed it so what is your tank size? Second, what type of plants do you want to grow? These will decide if need to get another bulb or stay with the one you have.

Actinics will absolutely help plant growth, no doubt about it. The wavelengths that actinincs ahve is very beneficial to plants.

That being said, you still do not count actinincs toward your total wattage nor lumens. They are not bright enough to affect the numbers enough to be beneficial.

Example. 55 gallon tank with a quad bank of 96 watt power compact flourescents. Going with 4 high light bulbs would give 384 watts and almsot 7 watts per gallon, way too much. If you put 2 full spectrum bulbs and 2 actinics you have 196 watts of countable light and 2 that have the spectrum needed but don't make make it a blinding light.

The best setup is to have multiple bulbs of which you get the needed wattage and lumens as well as other bulbs that finish out the spectrum for the plants to thrive the best.

Find what wattage you want, then put actinics in there to take up the other spaces. When I finally get the tnak I want I will have enough slots for 20 watts/gallon but will have less than 4 w/g because of the multiple "wattage uncounted" bulbs I will have in the fixture.

Zapher 09-04-2007 07:42 PM

Out of curiosity, i have had trouble with lighting in my brackish terrarium. It is a 65g tank filled halfway with water. I always wondered how much of the light spectrum is lost once it hits the water. Also i plan on moving everything into my 110 once i finish my DIY stand and canopy. I want to put on T-5's. I don't know if you are familiar with the common fluorescent bulbs known as life-glo, power-glo, marine-glo, etc. The T-5's would be by the same company and has the option of the three mentioned bulbs above. I was originally going to do 1 power-glo and 1 life-glo bulb but should i switch one out for the actinic marine-glo or add another ballast with 2 more bulbs, one a marine-glo?

Hope that made sense, i always feel like i confuse myself when writing these posts so worry about how horrible it is for everyone else to read.

Forgot to mention that the lighting is for both marginal and true aquatic plants.

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