15 watt light options for planted tanks.

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Aquarium Advice Regular
Nov 26, 2013
I have a basic 20g tanks with amazon sword and java. The light fixture is for 18" bulbs, but the only bulbs that size are 15watts. My java is barely hanging on, and the Sword lives, but doesn't really grow....at all.

Please, someone tell me I don't need a $90 light fixture.

You can buy a LED light, with T8 bulb you won't go nowhere...
Most things that will get you better light will probably be $70+
The first thing that comes to my mind is a finnex fuge ray. Finnex makes great lights, and the fuge ray is their light that is for low light aquariums like yours, which means it's cheaper, and you won't have to worry about CO2. It might be a good idea to read about PAR, it's a way of measuring light intensity that can be used by plants. I'm not an expert, but I think the fuge ray should give you better light than your existing light, but not so much that you'll have algae issues without CO2, as long as you don't run it too long.
Here's the 30" fugeray, I think that's the length of a 20 long aquarium. If your tank is less than 30", then you can get a shorter light which will obviously be less expensive.
Also another thing I just thought of, make sure your java fern's roots are not burried because they need to be tied onto a rock or wood. And anazon swords are heavy root feeders so they need root tabs put under them in the substrate.
You will certanly need a different lamp. At minimal you would need 40 watts to get the 2-3 watts per gallon you really need to grow. You may do well converting yours yourself. I too am investigating a new hood. Feel free to check my thread for ideas. I too have a lot to learn.
The watts per gallon rule isn't really used anymore because it doesn't take into account tank depth, wavelength, or distance from the light. PAR is a better way to measure lighting for plants, and the link I posted from TPT explains it very well :)
Another option I just thought if, is using CFLs. If you don't mind the appearance, you could get 3-4 clamp lights with 26w CFLs in each and that would give you decent lighting. I think it would be pretty cheap, too. Might have to play around with it a bit though so you can find the amount of light that doesn't give you too much and cause algae.
For some reason most of the guides I am digging up are written according to watts per gallon. While it's not dead-on accurate, it is good enough to begin picking out a lamp. It's a quick and dirty way but it is still effective. I've never heard of PAR (though I am far from knowledgeable) but I am sure it is more accurate, but takes more "work" on behalf of the aquarist.
My first thought is do you have a daylight spectrum light bulb in the fixture now? And how old is the bulb?
I have just 45 watts of t12 fluorescent tubes over my 75 gallon tank and i grew crypts, amazon sword, java fern, jungle vals and java moss in there no problem until the bulbs got too old. The Amazon sword will probably still need a root tab in the substrate near/under it.
If you can post some pics of the tank it might help.
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