A beginner's guide to lighting

[malkore]

Lighting is THE most important aspect of a planted tank...but nearly as important are CO2 and fertilizers.
I say lighting is the most important because if you don't have enough light, there's little to no need for ferts or CO2. In fact, without enough light, your plants are simply going to wilt and die.

To begin, that light that you bought with your tank isn't going to cut it. Those basic, single bulb plastic strip lights rarely provide even 1 watt per gallon. You can grow java ferns, most anubias and crypt species with that...but little else.
Therefore you need to either add more normal output (NO) fluorescents, or upgrade to a different lighting system: very high output (VHO) fluorescents, 'power' compact fluorescents (PC) or metal halide (MH). You could also overdrive your NO bulbs (ODNO) by upgrading the ballast, but I'm not a huge fan of this.

Lighting types

I would skip the VHO's because they get as expensive as PC, and PC is quickly becoming popular, which will lower the price in the next year or so. However if you happen to come across a great buy on VHO, go for it. The bulbs aren't quite as expensive as PC bulbs, but they don't come in as many spectrum choices suited to FW plants. VHO has become more of a marine lighting choice.
MH is ok for larger tanks, but the cost and setup involved make it impractical for smaller tanks (under 100 gallons). I do know of at least one person with a 40gallon hex tank that had success with a MH fixture.

These lighting options all vary in efficiency. Normal screw-in incandescents are very inefficient, and aren't used in aquarium lighting (as far as plants go). If you have a tiny tank with an incandescent light, you can get a screw-in power compact replacement from coralife that's a decent plant spectrum. (more about spectrum below)

Metal halides are better than incandescent, not as good as NO fluorescents...however since they put out a ton of light due to their size, they are handy on bigger tanks, where you might need 8 NO tubes, or just 2 MH lamps.

NO fluorescents are fine, and a wide range of bulbs are available for you to get the right spectrum, color temp, and visual appearance in the tank. Their only limiting factor is their bulky size as compared to power compacts.

PC's are like concentrated NO lights. A 20" long NO bulb is usually 18watts. A 21" PC bulb is 55-65watts. Now that does sound impressive, but wattage is just how much power the bulb consumes. Light output is expressed as Lumens. To keep the example simple, a NO bulb of 18watts might put out 1000 lumens. 18*3=54, so 3 of these bulbs would put out 3,000 lumens. A 55watt PC bulb puts out 4,800 lumens. So PC's take up less space per watt, with a higher output. (PC lumen output source: http://www.atlantalightbulbs.com/eca...ch=F55BX/AR/FS )

This is important because you might've heard the 'watt per gallon' rule (wpg for short). 1wpg is low light...2wpg is moderate, and 3wpg is high...and sometimes you might need 3.5-4wpg for those pretty red plants. Well this rule was created years ago and applies to NO bulbs. If you have 2.5wpg of PC's, that's a bright tank, and in my opinion there's no need to go above 3wpg with PC's in a freshwater tank, unless it's a deeper than normal tank.

The limiting factor on PC's is the cost, which gets pretty high....and that you have to totally replace your current lighting. I highly suggest taking the DIY approach to upgrading your lighting. Both www.ahsupply.com and www.hellolights.com have kits and parts for PC lighting. HelloLights also carries some VHO and MH supplies. I've bought all my Coralife fixtures from hellolights.com as well.

Spectrum & color temperature

Not only do you need a good quantity of lighting, you need quality as well. Plain white office fluorescent tubes ain't gonna cut it. Plants need peaks in light spectrum in the reds and blues. This is why the bulbs in flower shops look pinkish/purple. Office lights (or those in retail stores) are very greenish/yellow...not too suitable for plants.
Most bulbs have a spectrum on the side. If they don't, color temperature is a way to estimate a good bulb. Anything between 5,000k to 10,000k will be usable by plants. Most bulbs will be 6,700k, and will work fine. GE makes a really great PC bulb that's 9,325K (my link above is a cheap place to buy them). These are the bulbs that come with an All-Glass brand PC hood.
Be careful buying PC hoods...sometimes they come with 50/50 actinic bulbs...and actinic light is next to worthless for plant growth. Coralife recently started making Freshwater hoods that come with 6,700k bulbs in them. HelloLights.com carries a range of sizes.

Keep in mind that NO bulbs need to be replaced about every 6-9 months. ODNO bulbs every 3-4 months, and VHO bulbs 12-14 months. (all based on 12 hours a day use)
Power compact bulbs can actually be run until they no longer work. The phosphors used in these bulbs don't degrade as much as straight tubes, and also don't lose nearly as much intensity.

If you've ever tried plants, and they just died within 2 weeks, you probably need to look at insufficient lighting as the culprit.

*edit*
Bulb lifespan

How often do I need to replace my bulbs? A very good question...but answers vary.
Its generally agreed upon that NO bulbs need to be replaced at 9-12 months, as their phosphor coats inside teh tube degrades, causing the spectrum and light intensity to degrade.
I've never studied VHO because they don't get used much in planted tanks. My guess is that they last only as long as NO tubes do since they're manufactured in similar ways.

and for ODNO, you're looking at 4-6 months before they need replacing, as the over driving wears them out pre-maturely.

PC bulbs, however last longer. Due to the way they are made, the phosphors don't degrade as fast, nor does the intensity diminish as rapidly as NO's. I have seen recommendations to replace PC's at 12 months, 16-18 months, and also to just 'run them until they stop working'.

I am currently running 2x55w that are 2 years old, and 2x55 that are about 18 months old on my 75gallon...and I think they've finally gone south. So my recommendation is to plan for about 2 years on PC's, then get replacements ordered. If the plants still look good, just wait for a bulb to burn out. If everything else seems perfect (nutrients, CO2, water changes) but the plants just ain't kickin' it anymore, change half your bulbs one week, half the next.




(This thread is for information and resources only. Post questions in new threads. -- czcz, 9/06)

[Wizzard~Of~Ozz]

I was looking around on tropica's site and came across This

It shows the relation between Co2 and light, and their effect on plants in the aquarium. Some great information with some great understanding on why plants do the things that they do.

[czcz]

Alternative standards:

Ozz's Oh glorious Light
AA companion thread for Updating the WPG rule and lumens sq/in
Data from established tanks
Calc for theoretical/sample tanks

John & Mary Fitch's Lighting in Amano Aquaria

Rex Grigg's Minimum Light Threshold

Ivo Busko's A Comparison Between Light Sources Used in Planted Aquaria




(This thread is for information and resources only. Post questions in new threads. -- czcz, 9/06)