Since lighting is the most confusing aspect of a planted tank that's where we are going to start.
To have a successful planted tank you must have light and quite a bit of it. Unless you are converting a reef tank you don't have enough light. How do I know this? Because not a single aquarium kit out there comes with enough light for a planted tank. There are a couple of minor exceptions to this but you don't have enough light. Kits sold at the local fish store or Wal-Mart or PetCo or PetsMart just don't have enough light. They give you enough light to see the fish and try to prevent algae. That's it.
I want to add that any idiot can cram a bunch of light over a tank. But the real secret is getting that light into the tank.
You may have already stumbled across the "Watts Per Gallon" rule (abbreviated as WPG in the rest of this guide). The WPG rule works fine on tanks from around 20 gallons to about 75 gallons. It doesn't work on smaller or larger tanks. For more on why this is read here .
For tanks in the 20-75 gallon range you really need a minimum of 2 WPG. Now there are some plants that can survive with less light. But they will grow very slowly if at all.
NOTE: All watts are from fluorescent watts and all gallons are American gallons.
Let's say you are the proud owner of a 55 gallon kit from the local chain store. Well I'm sorry to hear that. I will cover tank sizes and shapes in the hardware section of this guide. But as for the light you either have two 15-20 watt strip lights or one 40 watt strip light. The WPG rule tells us you need 110 watts of light over this 55 gallon tank to get to the 2 WPG range. You can buy a commercial light fixture from several places that will give you this amount of light. One thing to watch for is that many of these fixtures are for reef tanks and will come with actinic bulbs or 50/50 bulbs. These are not good bulbs for planted tanks. The bulbs that you want for planted tanks should be in the 5000k-10,000k range. What's that k you ask? Well it's short for Kelvin. If you want to know what Kelvin is ask. I'm not going to confuse people here. I really like the GE 9325k bulbs. My plants are doing very well under them. They are a hard bulb to find but you can find them at the best price here.
I'm going to put in a plug for a company I have done business with many times. That company is AH Supply, They sell what I consider to be the best retro-fit kits available. The reflectors they provide make a huge difference in the amount of light that gets into the tank. They also sell basic wooden enclosures for those of us who don't have access to a wood shop or know our limitations. But for basic lighting you can mount their kits into the strip lights that came with your aquarium. The kits also come with everything you need to mount the lights except the tools. No trips to the hardware store to find a thing! And that's a plus in my book.
Now you may have already tried to grow plants with your stock lighting fixture. And chances are the numbskull at the Local Fish Store may have sold you a "Magic Plant Bulb" for your fixture. Well those "Magic Bulbs" won't help a bit till you get into the 2 wpg range.
If you really get wild and start getting your light into the 2.5+ WPG range you are going to need CO2. Actually CO2 will help the plants at any light level. See the CO2 section for more on CO2.
If you build your own light fixtures you might be tempted to use tin foil as a reflector because it's shiny, cheap and available. Well think again kid. Tin foil is not a reflector it's a diffuser. Don't believe me? Try this. Take a sheet of tin foil. Point one of those inexpensive laser pointers at it, or even a bright flashlight. Notice how scattered the reflection is? That's because the tin foil is a poor reflector. Shine that same light source in a mirror. Note the difference. White paint actually makes a better reflector in a DIY fixture than does tin foil. If you head to a craft shop or your local dope growers supply (hydroponics) store you should be able to find mylar sheeting. It makes a good reflector also.
Your lights should be on 10-12 hours a day. Leaving them on longer only invites algae.
NOTE: If you don't have adequate light leaving them on longer will not make up for the lack of light.
I want to take a minute and talk about a trend I see that really irks me. People that use shop lights over tanks. Sure they are better than a standard strip light but they still suck. I once had a 55 gallon tank with 160 watts of shop lights over it. And it sure did look bright. But I had problems with a lot of my plants. I switched to a single 2x55 watt kit from AH Supply and actually got more usable light into the tank. Sure the shop lights gave better coverage in the tank and into the surrounding room but the AH Supply kit basically blows the light straight down into the tank where it belongs. A simple experiment will show you what I mean. If you have a room in your house that you can black out you can take the shop light and hang it in the middle of the room and turn it on. See how nice and bright the room is? See how much light there is spread around the room? That's because shop lights are made to (surprise!) light up shops. Now take a AH Supply 2x55 watt kit and hang it in the room. See how bright the light is under the light? See how dark the rest of the room is? That's because the AH Supply kit is made to light up aquariums. I realize that not everyone can afford or obtain AH Supply kits. But there are better options than shop lights.
Ok, [rant mode on] I have seen a lot of people repeating the lie that deeper tanks need more light. That might be true if you are using crappy lighting systems or barely have enough light as it is. But if you use decent lighting systems with decent reflectors the depth of the tank doesn't mean squat. You might hear about spectral drop off or lighting decrease. Bullshit! If your tank was 30 feet deep it would be one thing. But the difference between 18" and 30" is not enough to worry about as long as you have good reflectors.
There are rumors running around the Internet that you need to replace your fluorescent tubes every year or so. I feel that is a myth. If you have high quality compact fluorescent bulbs you can run them till they drop. If you have low light levels and inexpensive standard fluorescent tubes then you can replace them every 12-18 months.
Last Updated Friday, February 9, 2007 11:15