Tuesday, October 24, 2006

Top 3 Mistakes When Starting a Planted Aquarium

For those of you starting out in the world of planted aquariums, I've picked my top three mistakes I've seen people make when starting an planted aquarium or converting a fish-only aquarium to include live plants. Consider this a crash-course in starting a planted aquarium. Most of these mistakes lead to the plants dying within a few weeks and, for those of us who don't give up easily, the process is repeated until either our patience or pocket is depleted. Often this is compounded by bad advice given by people at pet stores who often don't know a thing about plants, and even sell plants that aren't true aquatic plants. I'm sure many a potential planted aquarium enthusiast has been lost due to bad advice and these three mistakes. Here they are:

1. But it looks bright! - Often people try to grow plants under the light fixtures that come with an aquarium or come standard in a cheap hood. More than likely, this is a single fluorescent bulb, usually no more than 15 or 20 watts (steer WAY clear of incandescent, they just waste energy, heat your aquarium, and grow algae). The most critical element needed to grow live plants is light. Plants need light to photosynthesize, and without it, they may last a few days or a few weeks on their energy reserves, but eventually they will die. Many people are also mislead by bad advice into believing that the light that is sold with aquariums is adequate. The standard lighting that comes with an aquarium will typically only grow Java Moss and maybe Java Ferns and very poorly at that. If you like ugly, lanky, unhealthy plants go ahead and try it. No matter how bright it may look, it is not enough light. Plants only use specific colors of light, usually in the red and blue ranges. Humans perceive green as brightness. Therefore, what appears bright to us may not actually be helpful to plants. Always choose full spectrum lighting or specific plant growing bulbs, and at least 1.5-2 watts per gallon (WPG) is needed to grow the most basic of aquatic plants in an aquarium. Although this is not set in stone and the watts per gallon rule gets distorted with really small (under 10 gallons) or really big (over 75 gallons) aquariums, it is a good rule of thumb. The following breaks down what ranges qualify as different levels of light:
  • 0-1.5 WPG - Extremely low, pretty much nothing will grow
  • 1.5-2 WPG - Low, basic hardy aquatic plants will grow slowly
  • 2-3 WPG - Medium, most aquatic plants will grow fine
  • 3+ WPG - High, almost any aquatic plant can be grown
What must also be taken into account is the related effect of light levels on a plant. This brings me to mistake number two.

But I thought high
light = a beautiful aquarium! - Say you splurge and buy an expensive high output light fixture for your aquarium. Throw some plants in and sit back and watch it grow, right? Wrong. Light in an aquarium is like the gas pedal in a car, the more you push it the faster you go, but the quicker things get out of hand, and when it does get out of hand it gets ugly. Having high light is not always best, especially for someone who's new to planted aquariums. A basic understanding of a plant's metabolic process is required (don't worry, I won't go into details). It takes a bunch of raw materials and energy and outputs a finished product (new growth). Raw materials are fertilizers, chemicals needed for growth, and energy is light. If it runs out of any one of these inputs, the whole thing shuts down, and more importantly, it can only go so fast. So when you throw a plant under high light, it immediately kicks the internal mechanisms into high gear. The plants just shut down when they run out of any one of the many chemicals needed to grow. If you don't fertilize your tank, you will quickly find that all high light does by itself is grow algae, and lots of it. Fast. Real fast. For this reason, if you're just starting out, my advice is to get a medium or low light setup. You don't have to fertilize as much (if at all with a low light setup) and things won't be moving at such a fast pace (and thus get out of control so quickly). It's very hard to recover from a serious algae bloom because once it's taken hold, some types are impossible to remove. I've heard horror stories of people being forced to totally break down their tank because of algae. You've got to stay on top of it from the start.

3. But it was being sold as an aquatic plant! - Many fish stores sell aquatic plants. The problem is, many also sell plants that are not true aquatics. Often these can be found in big-box chain pet stores, where they make up 30-50% of the plants sold. Even at the local fish store, unless there is a dedicated employee who knows his or her facts, non-aquatic plants can be sold to an unsuspecting aquarist. Why these plants are sold as aquatic plants is beyond me, but I doubt it falls far from someone wanting to make a quick buck. They will survive fine underwater for a few months, maybe even a year, but they will steadily
decline until they finally die. Since they are not true aquatics, they cannot survive submerged for long periods of time. The only way to avoid these plants is to educate yourself. Certain plants always seem to pop up:

  • "Mondo Grass" Ophiopogon japonicus - This is a bushy grass with dark green leaves.
  • "Purple Waffle" Hemigraphis colorata - Dark green broad leaves with purple undersides.
  • "Aluminum Plant" Pilea cadierei -Dark green leaves with silver markings on the foliage.
Steer clear of these, you are just wasting your money, despite how pretty they may be. Can you imagine what would happen if fish stores were selling non-aquatic animals to put in your fish tank? Only by not buying these plants can we discourage fish stores and their suppliers from passing these off as true aquatic plants.

As long as you avoid these three mistakes, you should get past the inital transition into the wonderful planted aquarium hobby. Then you can start upping the ante and experimenting with fancy rare plants and high tech setups. It's a steep learning curve, but do your research and you will be rewarded with an aquarium that exploding with life and color that you just can't take your eyes off of!


  1. Hi, i'm using a 72 watts lightning system for my 502 gallon fish tank. It is a 2-piece PL light with each 36 watts. Is this enough? I've calculated and the figure seems to be too exaggerated? I actually need 251 watts?

  2. The rules slack a little for huge tanks, but 250+ watts on a 502 gallon tank is not exactly a lot. I have 260 watts on my 55 gallon.

  3. I have 340 Watts on my 125 gallon tank and it's still not enough to grow some plants. I'm thinking about taking it up to 450 or so.

  4. One aspect of lighting that seems to missed by comments and even this otherwise excellent (as usual I might add since I have referred many here) article is lumens per watt and PAR.
    Here is a quote:
    "Knowing your lumens per watt is often as or more important than watts per gallon. For example a T12 light that is rated at 20 watts with a total lumen output of 800 lumens has a lumen per watt output of 40. While a 13 watt T2 bulb rated at 950 lumens has a lumen output of 73 lumens per watt. This is a clear example that the watts per gallon rule is severely flawed as the 13 watt T2 (or two of these) is clearly the better choice for a 15 gallon planted aquarium (or reef) and this does not even take into consideration the PAR rating which is also important for plants/corals or lumens per length of bulb (space).
    This lumen comparison also applies to SHO, VHO, and Metal Halide all of which far out produce most T12 lamps in lumens per watt."

    This quote comes from this article: Aquarium Lighting

  5. Actually, there IS another way we can discourage nationwide chain stores from selling non-aquatic plants as true aquatic. Contact the Attorney General for your state. Contact the Better Business Bureau. Contact your Congressperson. If enough people complain long enough and hard enough about this unethical practice then things will change.

  6. I disagree that "0-1.5 watts/gallon extremley low, basically nothing will grow". I have a 20gallon with 1.5watts-gallon/Co2,ADA substrate and dose ferts every day and I can grow just about anything very well and without algae problems. This lighting on this tank is nothing special, just phillips "tornado" spirals X4 in a wodden hood to spread the light around the tank, the tank "pearls" nicely about an hour after lights on with this so called "basically nothing will grow " light setup. You should really try not to mislead people with completly false information. This article was complete rubbish!

  7. Again, WPG guidelines are just that, guidelines. Certainly not set in stone, and if you throw enough CO2 and ferts at a low light tank, you are likely to get some decent growth from some plants.

  8. Looking at fish in a square glass contraption is a fraction of the hobby. I find learning and applying the mix of biology, chemistry, and ART concepts a fun and REWARDING part of fishkeeping and aquatic plants. My point being, always seek more knowledge and progress in the hobby. (I'm a geek, I know, but I still have fun!)

  9. Top 3 mistakes are really interesting ..i think it should be remembered while buying a fish-tank


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