# 20 standard, light uses 2 clf



## pyrrolin (Jan 11, 2012)

Standard 20 gallon tank, light fixture uses two CFL bulbs. I am wondering how many watts each approximately for low light and medium light? Neighbors need new bulbs and I gave them plants but not totally sure what wattage I should recommend to them. I am thinking two 13 watts should be good but not positive. No good reflector either. when I looked at the light, I expected to see a t8 bulb but discovered two cfl.

Any tips on wattage would be appreciated.


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## flagtail (Jun 2, 2011)

http://www.amazon.com/GE-Lighting-89095-replacement-1600-Lumen/dp/B002YEXMUK

2 of those would work

I had 2 of these

http://www.homehardware.ca/en/rec/i...t-Light-Bulbs/_/N-1z141fb/Ne-ntc74/R-I3694715

didn't work so good...lol... it was .tonnes of algae....and on a 10 gallon


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## Professor Monkey (Jan 8, 2015)

flagtail said:


> http://www.amazon.com/GE-Lighting-89095-replacement-1600-Lumen/dp/B002YEXMUK
> 
> 2 of those would work
> 
> ...


The two bulbs you referenced both have the same colour temperature (6500k) which is good for plants. The bulb you said gave you lots of algae produces half the number of lumens that the one you recommended does. Two 1600 lumen bulbs, even without a reflector are going to be close to high lighting on a 20gal I would think.
For refereence, an 18" 15W T8 will produce 420 lumens and would be good low lighting on 15 gal.

I'd recommend the 800 lumen bulbs and keep the photo period on the short side until you can be sure algae won't be a problem.


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## pyrrolin (Jan 11, 2012)

Thanks for the tips


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## jart (Jul 26, 2011)

Of course keep in mind that bulb orientation plays a huge role. Vertically mounted CFLs will produce far more PAR than CFLs mounted horizontally.

Of course the best thing about CFLs is that you can play with differing wattages and if you pick the wrong wattage, you can still use the bulb elsewhere in your house.


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## flagtail (Jun 2, 2011)

jart said:


> Of course keep in mind that bulb orientation plays a huge role. Vertically mounted CFLs will produce far more PAR than CFLs mounted horizontally.
> 
> Of course the best thing about CFLs is that you can play with differing wattages and if you pick the wrong wattage, you can still use the bulb elsewhere in your house.


Bloody right!

You hit nail on head with that said!


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