part of "A Rich Person's Guide to Aquariums" by Philip Greenspun

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Plants in an aquarium serve several functions: There are two schools of thought on succeeding with a planted aquarium: low-tech and high-tech.


The low-tech planted aquarium is based on the idea that plants grow in dirt. The theory is that if you place garden or potting soil at the bottom of the tank, with a thin layer of gravel on top, this plus fish waste will supply the nutrients that the plants need. Supposedly you then won't need all of the plant nutrition supplements sold at aquarium stores because these are only required when the aquarium environment is sterile. A chief exponent of this point of view is Diana Walstad, author of Ecology of the Planted Aquarium, which is well worth reading even if you ultimately decide to go the high-tech route.

My personal experience with a low-tech aquarium started off dismal. I put a thick layer of supermarket potting soil underneath the gravel in a 90-gallon tank with 160 watts of light (4 48" fluorescent tubes) . It turned the water brown and yet supplied so little iron to the water that I could not get a reading from an iron test kit. The first batch of plants started to die within two days, with the leaves turning yellow from the tips downward. I consulted a couple of experts and they postulated that the plants were being overfertilized with phosphates from the soil. Their theory was that the deaths were too rapid to be from iron deficiency. Another worrisome factor was that the water in the tank is extremely soft. Boston tapwater contains no minerals. This may lead to CO2 deficiency because of the lack of carbonate hardness. Also, the tanks was being over-agitated by a couple of low-quality Tetratec Pro filters (see the filtration section for a discussion of why these are so terrible). Surface turbulence tends to allow CO2 to escape from the water.

With little to lose, I changed 80 percent of the water in an attempt to get rid of excess phosphates. The tank become quite clear. Then I dumped in double doses of plant mineral supplements. The plants began to recover a bit.

I left the tank on its own for two months. The water turned brown again. Brown-green algae proliferated. Many of the plants survived but none appeared to flourish. Maybe it was the algae but something botanic was using up the nitrate produced by the filter bacteria; nitrate levels were 0 despite the lack of a water change during those two months. I did a 90-percent water change and replaced the noisy ineffective Tetratec filters with a Rainbow-Lifegard system including UV sterilizer.


The high-tech planted aquarium was pioneered by Europeans and is sometimes referred to as a "Dutch Aquarium". You rely on nature for nothing. You use a purpose-made substrate. You fertilize that substrate periodically. You inject CO2 into the tank. Here is the formula that works for Phyllis, the woman behind, for a planted Discus tank: Plants in a high-tech aquarium grow much faster than plants in even the most successful low-tech aquarium. What has never appealed to me about the high-tech approach is the CO2 injection. If it goes awry there is a danger of killing the fish. If you are using a bottle-based system, you have to obtain a new bottle from a gas supplier every 3-6 months.


Whether you take the high-tech or low-tech route, remember that you'll want fairly strong lighting (1.5-2 watts per gallon is considered the minimum). The easiest way to get to this level is by purchasing the aquarium manufacturer's glass hood for your tank. Then toss as many compact fluorescent strip lights on top as will fit. Avoid standard fluorescent strip lights. They work great for a year and then the ballast begins to make an annoying mechanical buzz. Compact fluorescents have silent electronic ballasts.

Note that placing the tank near a window where it can catch sunlight also works.


If you want some inspiration, pick up the beautifully photographed books by Takashi Amano:

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