# Enough light for 20L?



## vmahaffe (Apr 26, 2008)

Got a gift card for Petsmart and was thinking about a T5 for my 20L. Would this one provide enough light? 1x24w
http://www.petsmart.com/product/index.jsp?productId=3060842

I would like to grow high light plants.
Thanks.


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## svenhipsta (Dec 16, 2009)

24watts / 20L (5.28 gallons) = 4.5 wpg. between 2 and 3 watts is generally considered "moderate."


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## El Exorcisto (Aug 10, 2006)

Did you mean a 20 liter or 20 long? If a 20 liter, then you'll be able to do some low-lights. If a 20 long, you are going to come up WAY short for just about anything...


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## vmahaffe (Apr 26, 2008)

Sorry, 20 long, not liter. How much lighting would I need using T5's then? 2x24w?


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## El Exorcisto (Aug 10, 2006)

2x24 still only puts you around 2 watts per gallon, and IMO that's skinny unless you are doing a Walstad type aquarium (El Natural). I would prefer 60 watts or better, preferably more like 80. I am, however a high tech kind of guy with pressurized CO2 and EI dosing...


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## vmahaffe (Apr 26, 2008)

Since they are T5 with reflector, doesn't the watt/gallon rule get thrown out?


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## El Exorcisto (Aug 10, 2006)

If the watt per gallon rule still applies pretty true even with a halide pendant, then yes, I feel it still holds for T5s with reflectors. No reflector will be 100% effective, AHSupply's are 62% effective. Even at that you are looking at 2x24 to get 3 watts/gallon which is enough to grow decent stems and healthy rosettes. 3x24 would do just about everything you need, if you don't mind spending the money.

A reflector doesn't magically negate the absolute rule that more energy pushed through bulbs makes more light. Reflectors don't magically make a 24 watt bulb enough to go nuts with high light plants. If it did, I would run one 54 watt over my 55 instead of 180ish watts of ODNO T8s.


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## endgin33 (Jun 10, 2008)

Honestly, for good coverage and "High light" conditions I would suggest that 2 of the 39 watt hagen's t-5's would be very good. Ideally, two separate fixtures (rather than a twin t-5 fixture) would allow you to run one as the primary, with a burst during the middle of the day on the second. I don't know if you are in the "gift certificate scenario" where you are somewhat limited in your choice of source, but that would do the job.


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## vmahaffe (Apr 26, 2008)

endgin33 said:


> Honestly, for good coverage and "High light" conditions I would suggest that 2 of the 39 watt hagen's t-5's would be very good. Ideally, two separate fixtures (rather than a twin t-5 fixture) would allow you to run one as the primary, with a burst during the middle of the day on the second. I don't know if you are in the "gift certificate scenario" where you are somewhat limited in your choice of source, but that would do the job.


I am giving up on the Petsmart gift card idea and just looking for a suitable fixture to give me high enough light. Thinking about a couple of the Coralife fixtures available in 30" size. There is one that uses twin 18w T5NO. I read someplace that others have been using this fixture on their 20's with good results and they are only $50. If one isn't cutting it, I could always add a second one.


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