Filters

By Jim Kelly jkelly@landau.ucdavis.edu

This is not a big issue in planted aquaria as long as you don't have TOO many fish. The plants love to absorb any waste products that the fish give off, so you don't need huge cultures of nitrifying bacteria. Filters serve other purposes though:

  1. They remove floating debris from the water so that the tank is nice to look at.
  2. They provide water circulation, which is important because the plants absorb CO2 and nutrients through their leaves, and in the absence of good circulation a layer of water which is depleted in CO2 and nutrients will form between leaf and the rest of the water.
  3. They provide a convenient place in which to inject CO2 into the water (see the section on CO2).
I use Hagen "Aqua Clear" back filters for my aquaria. Any filter that uses an electric motor (not air bubbles) and is not an undergravel filter will do.

Heaters

These are unnecessary in most houses that are comfortable, but they're cheap so you might buy one anyway and set it at 74 Farenheit. Temperatures near 80F are too hot for plants, and should be avoided unless the fish cannot acclimate to lower temperatures.

Undergravel Filters

Don't use them in planted aquaria. Plants like fine soil at their roots and UGF's will pull the fine clay below the filter plate. I remember someone once saying, "undergravel filters grow beautiful roots and poor plants." The roots love to be able to respire, but many nutrient ions will be oxydized to unavailable forms with all that well-oxygenated water flowing through the substrate, and the plants will suffer.

Air pumps/Bubblers

Don't use them. Any fresh air contacting the water will deplete the CO2 dissolved in the water to very low levels. The plants produce enough oxygen to last all night even for most tightly sealed aquaria. However, if your fish are gasping at the surface in the morning (I've never seen this) then turn on an airstone ONLY AT NIGHT when the plants don't use CO2.

Power Heads

These are not necessary, but if you already have one you can use it for additional water circulation in a 55 gallon or larger tank. Don't use it with an undergravel filter (since you shouln't be using one anyway).
bruce@hallman.org
To Bruce Hallman's aquarium plant home page.