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tsweers89 11-16-2009 12:57 PM

Twin t5 on 72g bow to much light?
So i am finnaly almost ready to get my 72g bowfront running and planted. Last thing is to get the lighting. Well i originally planned on a single 48" t5 Glo fixture but happend to sumble upon a deal for a twin 48" t5 glo fixture for $65 more than half the price of the single t5 i was planning on getting. So im woundering since a 72g bowfront is taller than a regualr 75g would it work ok. Im going for a planted tank that wont need co2 injection. Plan on using fertilizers and seachems flourish excel. So what im asking is will i need co2 with this lighting or can i get away without it and not have to worry about algae blooms. Any info or input would be appreciated.


Byron 11-16-2009 01:36 PM

My recommendation is to use either a single-tube T5 or a double tube regular (T8, T12) fixture. I prefer the latter because with two tubes you can mix types. Plants have been proven to exhibit better growth under a mix of full spectrum and cool white, then under full spectrum.

The reason I do not recommend double T5 is the intensity of the light. T5's are considerably more intense than regular fluorescent tubes of the same type. Studies have shown that two T5's are close to three regular tubes, and that is too much light over a 4-foot tank set up as a low-tech or natural planted aquarium.

I have two regular tubes over my three largest tanks; you can see the effect in the photos under my "Aquariums". I use one full spectrum 6700K tube and one cool white tube on each tank. The blue and red provide the plants what they most require, the green in the full spectrum balances for natural colours in plants and fish. Even on my 115g which is 5 feet, the two 4-foot tubes are plenty. When I replaced a broken fixture this past summer, I tried a twin-tube T5 on this tank for a full week and it was way too much light. I went with a dual-tube regular.


WisFish 11-16-2009 01:50 PM

The quick answer is that fixture should be fine. It should give you about 10,000 lumens. My t-8 3 bulb fixture on a 55gal produces about 9,000 lumens. I know the all-glass twin tube fixture with 2 t-8 bulbs produces 7,000 lumens.

The old standard of watts per gallon was based on the T-12 standard bulb which produced about 3000 lumens per 40watt bulb. So 75 lumens per gallon is equal to the old 1 watt per gallon. Using this figure, to have 2 watts per gallon on a 72 watt tank would be 150 * 72 = 10800 lumens. Going over this usually requires CO2.

But a lot depends on the types of plants you decide on and how heavily planted you make the tank.

tsweers89 11-16-2009 05:46 PM

I figured if it gets to be to much light and I have an algae problem I can always swap out one of the bulbs for a actenic bulb, jus gotta deal with a little blue.

Byron 11-16-2009 06:05 PM


Originally Posted by tsweers89 (Post 275343)
I figured if it gets to be to much light and I have an algae problem I can always swap out one of the bulbs for a actenic bulb, jus gotta deal with a little blue.

That doesn't work. While the plants can't manage with the actinic, algae will. If you have more intense light than what balances the nutrients which includes the CO2 from the fish, the only solution is to reduce the light period. I wouldn't go below 8 hours though. Another trick is lights on for 5-6 hours, off for 2, on for 5-6. Plants seem to grow fine with this, algae doesn't. My overriding concern though is always the brightness for the fish. I have forest fish, tetras, hatchets, pencilfish, corydoras, etc., and they come from dimly-lit waters and without going into the details I know they sparkle better with less intense light. I believe they are less stressed. On a purely economic note, lights take power and why have double the energy use when it isn't necessary?


tsweers89 11-16-2009 07:16 PM

Figure I can grow more diffrent plants with morelight, I want some type of grassy plant on the bottom and that usually takes some good light, if all else fials I'm sure I can sell it for what I bought it for. So wat bulbs do you reccommend? I was looking at the life glo2 but the life glo looks less intense so I figured I would go with that. I also could use some floating plants on the surface to cut down on the light if it gets to be to much.

Mikaila31 11-16-2009 07:26 PM

I think it will be fine, you WILL deal with algae when you first set it up. But if you keep on top of it the tank will balance out.

As far as grassy plants, I would go for some dwarf/chain swords. Hairgrass will need more light IMO.

tsweers89 11-17-2009 07:06 PM

well just picked it up. Still has the stock bulbs in it though, the blue and white daytime. What do you guys recommend for bulbs? I can't seem to find the life glo for t5. Any links would be appreciated. One step closer to getting this tank going.

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