# More T8 vs Less T5?



## cdlourie (Feb 6, 2012)

Hey, I'm pretty new here. I am going to be setting up what will be a DIY High-Tech 50g. So what is the general consensus on this:

Should I get more (possibly 6) 4ft T8 Bulbs over my tank (30 watts each, 3.6wpg) or 2 4ft HO T5 bulbs (54 watts each, 2.16wpg)? 

I'm really shooting for the T8 fixture, just because this is a DIY project and the setups cost the same amount, around 100 bucks. Also with the T8, I could have multiple different color temperature bulbs, ultimately producing a pretty close replica of the "Natural Light" spectrum. Please, any comments and opinions are much appreciated!

Edit: I also forgot to mention, the fixture will not be resting on the tank lid, but probably around a foot above it, with reflectors!


----------



## Seattle_Aquarist (Mar 7, 2008)

Hi cdlourie,

Welcome to APC! What is the depth of the tank? Also, with that wattage I assume you are going to have CO2?


----------



## cdlourie (Feb 6, 2012)

Yes. CO2, and dirt capped with flourite. By depth I'm assuming you mean up and down, not front to back? Up and down it is 18", as well as going front to back. I lied when I said it would be a foot off, probably around 4 or 5 inches. Any other questions? I'm eager for any input!


----------



## cdlourie (Feb 6, 2012)

Bump?


----------



## Zapins (Jul 28, 2004)

I think the T5s will give you better penetration since the reflectors on most are pretty good compared with the T8 ones. Both fixtures will work though.


----------



## XMX (Feb 17, 2011)

I've grown plants with both T5 and T8. However, I like the T5 HO much more. The bulbs are much brighter and the plants seems to do better, also.


----------



## bosmahe1 (May 14, 2005)

If it will be raised off of the tank, I would use T5's for penetration. T8s could be better if it were resting on the tank. I have been using Nova Extreme and Catalina T5s and have to think more about limiting the light somewhat since my fixture is directly on the tank. My ceiling is 12 feet and I don't like conduit for suspending the lights.


----------



## Newt (Apr 1, 2004)

You have the right idea with mixing bulbs to get a natural light. This is what I have always done and usually end up with a nice white light (when all are on). You also need to look at the overall output of the bulb - how many microeistiens it outputs. Remember watts is input. Two very efficient T8 bulbs are the Philips Aquarelles and the ADV850. I have a normalized spectral graph at home that I will post later that shows which bulb is the strongest at a given nanaometer.

Good T8s will work well in an 18" deep tank. Obviously a T5HO will be better. I built my own light hood and have a T8 in the center with a T5HO on either side. I used good reflectors.

I wish people would, when referring to T5 diameter bulbs, correctly identify if its a T5 or a T5HO. The T8 bulbs I mentioned can actually output more energy that many T5 bulbs.


----------



## Newt (Apr 1, 2004)

Below is a normalized plot of some bulbs output power. The ADV850 and Aquarelle are T8s and the PLL950 is a 55 watt biax CF (basically a T5 bulb) The two Philips T8s blow it away.


----------



## cdlourie (Feb 6, 2012)

Sorry, not to be stupid, but could you interpret that graph a little more for me. I'm a chemistry dork, not an electrician


----------



## Newt (Apr 1, 2004)

Visible light (electro-magnetic radiation) is from 400 nanometers (nm - a wavelength) to 700nm. This is light we humans use to see and plants use to create photosynthesis. The best light for plants is approx 430nm (blue light) and 650nm (red light). Bulbs emit light thru out the visible spectrum and the graph shows where the bulb is strongest throughout the visible spectrum. This is called a spectral output graph. The higher the peak the stronger the light is at that given nanometer.

The blend of all those peaks and valleys in the visible spectrum of a bulb gives it a particular color and is typically interpreted as a kelvin rating which is a temperature scale. You could have 2 bulbs with say a 10,000K (kelvin) rating that have different spectral outputs.

There are some stickys on this subject in the Lighting Forum.

An electrician may or may not know this but a physicist and biologist would. An electrician would know most 4ft T8s are 32 watts. I have some that are 36 watts. T8s also come in T8HO.


----------

