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lighting an 80 gallon... WPG?

1381 Views 13 Replies 5 Participants Last post by  Nodnarb, 
N
I want to mount a fixture in the canopy of my 80 gallon freshwater. I am setting the tank up to be lightly planted and its been suggested that i use a T5 fixture with 6500 or 6700K color bulbs.
I just dont know how many watts i need, is the old 2 WPG and outdated "standard?
Id been looking at this:
http://www.fishneedit.com/t5ho-4ft--2lamp-aquarium-light.html
looks like it would be 108 watts.

They also have a 4 bulb unit that will fit but is out of stock that would be 216 watts total, do i really need that much?
This is going to be a topical community tank to start along with an undetermined type of plants variety. This is going to be a test somewhat.

What could i be capable of growing with the 2 bulbs 108 watt with no CO2?
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Darkblade48
I would suggest you take a look at Hoppy's sticky, which is posted at the top of these forums.
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Larry Grenier
What are the dimensions of that tank?
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Wasserpest
If you are going for low tech, no CO2, I think the 2x fixture would be good. Getting the 4x fixture would require a regular fertilizer dosing regimen and good levels of pressurized CO2.

Of course you could use only half of the bulbs for the time being and add more when you feel you are ready or your plants need it.

The W/gal rule was better suited to older fluorescents with mediocre or no reflectors. For T5s with good reflectors, you need to adjust it way down.
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N
the tank is 48 3/4 wide x 25 3/4 tall x 18 1/2 deep.

i HAVE a fixture that takes two dual tube 21 inch straight pin bulbs.


Since the fixture had only one good bulb (10k) i started looking at prices for 6500k bulbs and decided to look at entire T5 fixtures. I happend to find a guy on eBay that is selling 4 of these bulbs ( 65 watts each)for 25 bucks shipped plus i can get my choice of color range.

So now im wondering where i would be in the "lighting range" with two 65 watt 6700K (ultra daylight) bulbs in this fixture? I.E would this be low light, low/med etc.
he offers these "colors"
o Actinic 460nm
o 12000K Premium Daylight
o 6700K Ultra Daylight
o 50/50 ( Half 12000K daylight. Half Actinic 460nm)
any use for any of the others?

I plan on 1 inch of peat/sphagnum 1 inch of sand 1-1.5 inches of pea gravel and substrate.

a side note, the fixture says to replace bulbs with 55 watt only, am i setting up and problem if i do use 65 watt?
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Wasserpest
Don't worry about 55 vs 65W, no big deal. You want to avoid the actinics as they are for reef tank (blue light). 6700K should be your safest bet. Sometimes higher color temps can be good, sometimes they end up too blue.
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H
The light with probably only give you low light if it even does that well. Most of the older fixtures for 65 watt PC bulbs had poor reflectors, and without very good quality reflectors they didn't produce much light. Even if the fixture uses AH Supply quality reflectors you would only get low to low medium light at best.
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N
Hoppy said:
The light with probably only give you low light if it even does that well. Most of the older fixtures for 65 watt PC bulbs had poor reflectors, and without very good quality reflectors they didn't produce much light. Even if the fixture uses AH Supply quality reflectors you would only get low to low medium light at best.
Click to expand...
Thats what i was afraid of.

I got an email from the retailer of the 4ft x 4 bulb unit:
http://www.fishneedit.com/4ft4bulbs-with-l44.html
and they are out of stock, dont expect product for 2-3 months.

they DO have a 3foot 4 bulb fixture that could work..
http://www.fishneedit.com/3ft4bulbs-with-l34.html
is that wide enough for a 48 inch tank? That only leaves 6 inches on each end...

Where would that put me in the light level "range"?
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H
A 2 bulb T5HO light fixture is all you need for the plants. With CO2 you can then grow anything you want to. A 4 bulb fixture is really way too much light unless you hang the fixture 8-10 inches above the top of the tank.
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N
Same would go for the 36inch 4 bulb? to much light? the fixture will be inches form the top of the tank under a canopy.
Does anyone use rheostats on tanks lights? do you have to change the ballast? im just thing, if i get a 4 bulb fixture i can "turn down" a set of bulbs as needed...
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H
Unless you have an expensive dimmable ballast you can't turn down the intensity with a knob. But, most 4 bulb fixtures can be run with just two bulbs, which cuts the intensity in half. Some of those fixtures can be had with separate switches or separate electric cords for each set of two bulbs.
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N
the one im looking at does have separate cords and swishes for each "set" of bulbs, i am curious thou as to if i should go with the 36" 4 bulb or the 48" 2 bulb.
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H
The two good reasons for using the 4 foot fixture are:
It matches the tank length.
Four foot bulbs are much easier to find in the color temperatures you will want.
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N
Hoppy said:
The two good reasons for using the 4 foot fixture are:
It matches the tank length.
Four foot bulbs are much easier to find in the color temperatures you will want.
Click to expand...
Good points, ill go with the 4x2

The fixture retailer has said they would sell me two of the 4x2' s (normally $90 each) for the price of a 4x4...150.00.
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