Light

Panda

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Jun 14, 2008
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Hi !

I'm planning a new tank around here for Xmas- January. It will have only male guppies.
From what I remember a 40 gallon breeder is 36 x 18 x 16 inches. I want to grow a carpet of glosso but I will not use CO2 on this one, only excel. Another option is a 30 gallon ( 36 X 12 X __??forgot ).

The question is what light should I use??
I have been looking a 36 inches T5HO Fixture with 2x39 w (78 watts). I just want to play it safe with this tank, no high light, no CO2 and hopefully no algae with proper care. I am not setting up a low maintenance tank, just a low light with normal weekly water change, EI ... any advice or suggestion?
thanks
Omar
 

VaughnH

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Two watts per gallon of T5HO light is not going to work on a 40 gallon tank without pressurized CO2, unless you hang that light several inches above the tank. T5 lights are much more efficient in providing light intensity than other bulbs are. Consider that many people get by with a single 54 watt T5HO light over a 55 gallon tank, and use pressurized CO2 and EI fertilizing as if it were a high light tank.
 

Panda

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Jun 14, 2008
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Thanks VaughnH,

what do you suggest ? the light will be right on top ( around 3 inches )
I have not decided between the 30 or 40 gallon.
 

VaughnH

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I think I would use one T5HO, 39 watt bulb on a 30-40 gallon 36 inch long tank. Given that you don't want high light, and don't want to use CO2, this should be about right.
 

Panda

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Jun 14, 2008
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h
VaughnH;31332 said:
I think I would use one T5HO, 39 watt bulb on a 30-40 gallon 36 inch long tank. Given that you don't want high light, and don't want to use CO2, this should be about right.

How about a 55 or a 65 w PC ? Too much? Not enough?
 

VaughnH

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Right now I have a single 55 watt GE9325K bulb lighting a 30 inch long 45 gallon tank, and it is suspended 6 inches above the tank. The low light plants I have, mostly crypts, are growing very well.

It is going to be very nice when we all have access to a good PAR meter to better characterize the light intensity we have in our tanks. Even if all we have is a PAR reading right under the bulb, at the substrate level, that will be much better than the guessing we now do with watts per gallon of various bulbs and fixtures.