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General Instructions for Setting Up a Planted Classroom Aquarium

by Karen Randall

[Editor's note: This article has been reprinted at the request and with permission of the author.]

The Tank

For most classrooms, a tank between 10 and 30 gallons is the best size. Smaller tanks can be managed, but require more attention to detail. Larger tanks usually take up more space than can be spared. Certainly, if you have a tank donated that is outside this range, don't hesitate to use it, but be aware that these instructions will have to be modified.

If possible, use a tank that is longer than it is tall. Tall, narrow tanks and those of unusual shapes are difficult to light adequately, and are also hard to work in. Some of the best tanks are:

All of these tanks can be outfitted with commonly available aquarium equipment. Larger tanks are good for common areas, but often take up more space than can be spared in a class room. Smaller tanks can be managed, but require close attention to maintenance and must not be heavily stocked.

Other equipment and supplies


Enough good quality fluorescent lighting to reach at least 2 watts per gallon. An exception to this rule is the 10 gallon tank. This tank is small enough and shallow enough that you can usually get adequate growth of shade tolerant plants using a single 15 watt bulb as long as the bulb is less than 1 year old, and of good quality. Except for the 29 gallon "high" tank, all of the other tanks mentioned can be adequately lit with two bulbs of the largest size that will fit on the tank. i.e., two 24" 20 watt bulbs over the 20 gallon tanks, and two 36" 30 watt bulbs over the 30 gallon tank. For the 29 gallon size, you will need three 24" 20W bulbs for adequate light. Aquarium strip light fixtures come as either double or single bulb fixtures. You can use any combination of single or double bulb fixtures that will meet your needs.

Some good brands of bulbs are:

These or comparable bulbs are available through Grainger at: if you can't find them at a local lighting shop.

Glass canopy


150W heaters are probably adequate for the 10-20 gallon tanks, 200W heaters will be adequate for the larger tanks. Buy a good quality submersible heater. Don't skimp here... a classroom tank is left unattended too often to risk your plants and animals to a faulty thermostat! Acura, Visitherm and Ebo Jager are three reliable brands that are widely available.


Any aquarium thermometer will do, but I prefer the stick-on-the-glass liquid crystal type for several reasons. They are unobtrusive, but easy to read, they are inexpensive, and most are marked with both Fahrenheit and Celsius scales which makes them another useful learning tool.


Do not use an under gravel filter or other air driven filter in a planted tank. It will drive off needed CO2. Use either an internal or external power filter. There are many good ones on the market. My preference is for those that have rinsable, reusable filtration media rather than those with disposable "cartridges". They are less expensive to maintain, and more environmentally friendly. Any good pet shop can tell you which size filter to get for your particular tank, but it is better to slightly oversize the filter rather than skimping. A couple of reliable brands of outside power filters are Marineland and Hagen. Duetto internal power filters are excellent in a number of applications.

Undergravel filters do have their use in Rift Lake tanks, and in other application where plants will not be used. They are inexpensive, and provide a huge amount of biological filtration. If an undergravel filter is to be used, you will have to also purchase either powerheads or an air pump to power it. Check with your local pet store for appropriate sizes.

CO2 Generator

See specific directions for making a yeast reactor.

Electrical equipment

Most classrooms are short on available electrical outlets. Use a heavy duty power strip to provide power for your aquarium equipment. If you cannot locate the tank near an outlet, use a heavy duty extension cord. You will also need a light timer (like the ones used when people go on vacations) to turn the tank lights on and off each day.


Remember that an aquarium is heavy! Filled, it will weigh close to 10 pounds per gallon. If you have a sturdy counter, that should be adequate. 10 gallon tanks can be placed on a sturdy table. Larger tanks really need a properly designed aquarium stand.


You can either use fine natural color aquarium gravel, or find a less expensive source. We use "traction sand" from our local hardware store. What ever you use, it should be between 1-3 mm. in size, and not contain calcium carbonate bearing rock. You can test this by placing a drop or two of muriatic acid (available at the hardware store) on a sample of gravel. If it foams, don't use it.

You will need about a 25 pound bag for a 10 gallon to 20 "high" tank, you'll probably need a 50 pound bag for the larger tanks.


This is an iron rich tropical clay that will serve as the nutrient base for your plants. Try your local pet store and ask if they either carry it, or can order for you. If not, here are some other sources:

Pet Warehouse
Schoeler Enterprises
241 County Rd.
Apple Valley, MN 55124
Monolith Marine Monsters

These companies all carry other planted tank related products as well.

Tank Set Up

These directions make the following assumptions about your tap water:
KH (carbonate hardness): reading of between 3 and 8 KH. (test kit, or have the pet store do the test for you)
Phosphate: below .5 mg/l (test kit, or water department report)
Nitrate: Below 10 mg/l (test kit or water department report)

If your tap water does not fall within these parameters, you will need to make some modifications. Contact me at for specific suggestions.

Place the tank on a stable, level surface. If there is even the slightest unevenness in the support, the tank can develop leaks. If you have any question about the surface that you are placing the tank on, place a couple of sheets of corrugated cardboard, or a sheet of styrofoam under the tank. Any excess can be trimmed off close around the tank. This is also a very good idea if you are using an open metal aquarium stand. The styrofoam will prevent heat loss from the bottom of the tank.

Before you go any further, fill the tank with water, wait twenty minutes to test for leaks and empty. This may seem like an annoying waste of time, because most tanks will not leak. But believe me, if you've bought the one that does, you will be much more annoyed if you find out about the leak after the tank is fully set up and running.

Install the thermometer, filter and heater, but don't plug anything in yet. Set your heater to approximately 76F unless you will be using fish that specifically need warmer (like Discus or Rams) or cooler (like Goldfish or White Clouds) water.

Rinse your gravel under running water until the water runs clean. The better you rinse your gravel, the less cloudy the tank will be when it is first filled. Mix laterite into damp gravel in a bucket. Use enough gravel to make an approximate 1 to 1 1/2" bed in the bottom of the tank. Be prepared, this step is messy! You might want to wear rubber gloves. While you want the gravel to be damp, try to avoid introducing any standing water to the aquarium.

Next cap the substrate with enough plain rinsed gravel to bring the total depth of the substrate to 3". With a 10 gallon tank, you can get by with a gravel bed of 2 - 2 1/2". Level the front edge of the gravel carefully so that it looks neat once the tank is filled.

If you are planing to use driftwood or any decorative rocks, they can be placed in the tank now.

The next step is to fill the tank about 3/4 full of water. The water should be between 70-80F. The exact temperature is not critical, but you want to be within a range that will not harm the plants. How you fill the tank will make the difference between a tank that will be crystal clear by morning, and one that can take a week or longer to settle down.

Get a shallow saucer or bowl and place it on the gravel. VERY slowly, TRICKLE the water onto the saucer. let it gently overflow, filling up the tank. When the saucer is completely submerged, you can speed up the flow _a little_, still aiming the flow at the plate. If this is done carefully, the water should be quite clear from the very beginning. If you aren't careful enough, don't panic. The tank will look cloudy for a few days, but it will eventually settle out.

When the tank is about 3/4 full, it's time to plant.

Here is a list of good sturdy beginners plants. Those with a * are particularly good "nutrient sponges", and should be emphasized in a start-up tank:

Common Name Scientific Name Origin
Java Fern Microsorum pteropus Asia
Java Moss* Vesicularia dubyana Asia
Water Sprite* Ceratopteris thalictroides World Wide
Water Wisteria* Hygrophilla difformis Asia
Small Leafed Hygro* Hygrophilla polysperma Asia
Giant Hygro* one of several Hygrophilla sp. Asia
Willow Leaf Hygro* Hygrophilla angustifolia Asia
Valisneria or Tape Grass Valisneria sp. New World and Africa
Sword plants Echinodorus sp. New World
Rotala rotundifolia* same Asia
Milfoil or Foxtail Myriophyllum sp. World Wide
Ambulia Limnophila sp. Asia
Fuzzy Duck Weed Salvinia sp. New World
Anubias barteri same Africa

All of these plants should be readily available. If your local pet shop doesn't regularly stock them, they should be able to order them for you from their supplier. Beware of choosing plants for your aquarium just because they look pretty. Just because they are submerged in the pet store doesn't mean that they are aquatic plants. Many pet stores sell a number of terrestrial plants as aquarium "decorations". These WILL NOT survive long term, and as they deteriorate, they will add to the waste materials in your tank. There are also a number of very tempting red plants for sale. While some of these _are_ good aquarium plants, most need very strong light, and are a little more sensitive than the species listed above.

"Rosette" or "crown" plants are planted individually in the substrate. Make sure that the crown itself is above the substrate surface. Only the roots should be buried. This is also true for the thick rhizome of Anubias plants.

Stem plants are usually sold in rootless "bunches". They should be removed from their elastic band or lead weight, and planted no more than 3 stems at a time. They will quickly root themselves under good conditions. If they tend to float out of the substrate in the beginning, you can place a few small stones around the base. Another trick is to leave them floating for a week or so. Usually they will have begun to develop roots in that period of time, and it will be much easier to keep them down.

Water Sprite can either be left floating, or planted in the substrate.

Salvinia (and several other similar small plants) are floaters. Remember that they increase quickly, and remove most of them when you do other tank maintenance. Don't let more than 1/3 of the water surface become covered with these plants.

Java Moss can be either left loose, or tied (or stapled) onto driftwood.

Java Fern does not usually do well with its roots in the gravel. It is best to tie or rubber band this plant to rocks or driftwood. You can even just wedge some in between two stones.

Any plants that come in plastic pots should be removed from the plastic pots, (this may require cutting the pot away with scissors) and have the rockwool removed from their roots before planting. The rockwool is used to grow the plants, and protects the roots during shipment, but it may contain hydroponic solution which can cause algae problems in the aquarium.

Now that the tank is fully planted, it is time to fill it to the top. It should be filled to above the plastic "frame" and close to but not touching the lip that holds the cover glass. This is where the water level should be kept at all times for several reasons. If you allow the water level to drop, the water returning from the filter will splash down onto the surface, creating a great deal of turbulence. This will drive off the CO2 that we are trying to add to the tank. Additionally, the greater distance that light travels through the air, the more it will scatter, and the less that will reach your plants within the tank. On a very brightly lit tank, this is a minor consideration. With a moderately lit tank such as we are setting up here, we need to conserve our resources! Do not, however, go in the opposite direction and keep the tank full enough that the water touches the glass. This would completely stop gas exchange, which is not a good idea either!

The last thing to do is to plug in all your equipment, and see that the light timer is set for about 12 hours on and 12 hours off. You're in business!

Wait at least one week, preferably two before adding fish to the tank. At the two week mark, you can add algae eating fish. My favorites are Otocinclus, which should be purchased in groups of at least 3, and Siamese Algae Eaters (Chrossocheilus siamensis). Siamese Algae Eaters are not available in all areas of the country. They will also eventually get too large for a 10 gallon tank and will need to be traded back in to the pet store for a new, smaller specimen. If you can't find SAE's, Bushy Nosed Cats (Ancistrus sp.) are a reasonable alternative, as are some of the Clown Plecos. (Peckoltia sp.) Ghost or Glass shrimp are also good algae eaters, and are interesting to watch, but will most likely become fish food once the tank is fully populated. You'll have to decide whether your kids (and parents!) can handle that or not.

Do not feed your algae eating residents for another two weeks. Their job is to eat any algae as it appears. They won't do that if you make life too easy for them.

At the end of the first month, your plants should have settled in and be growing well. The algae eaters should be keeping up with most algae, although it is still normal to need to clean the glass from time to time. At this point, you can start stocking your tank with its final residents. You can also begin your regular maintenance routine. (see article titled: Class Room Aquarium Maintenance Schedule)

Don't fall into the trap of overstocking the tank, either in terms of numbers of fish or numbers of species. In a 10 gallon tank, 3-4 species is more than adequate, while the 20-30 gallon tanks can accommodate a few more. The fish will display more natural behaviors, and the children will learn more than if the tank is stocked with the "Ark mentality" (two of these and two of those).

For class room tanks, my personal preference is to stick with compatible fish from a single geographic area, particularly if you can pick an area that is relevant to other class room studies. But of course, this is a matter of personal preference, and as long as the species chosen are compatible, and occupy different areas of the tank, the fish will not care that they come from different continents! If you want to be completely true to your geographical theme, you can choose plants native to those areas as well.

If possible, pick one species that stays near the surface, one species that is a mid water swimmer, and another that stays near the bottom. Make sure you buy multiples of any schooling fish. An absolute minimum number of any schooling species is 3-5 individuals, 12 or more will allow the children to observe true schooling behavior.

Steer clear of fish that are known to be scrappy unless you have an experienced aquarist that can help you plan a community around them. There are so many beautiful, interesting and peaceful species available that it makes no sense to set yourself up for problems. Also avoid fish that are known plant eaters. In another article at this site, we will have lists of specific communities that have worked well for us. There are many, many variations. Let you kids do their homework! Let them research what fish might work well together during the month that you are waiting for the tank to settle in.

Once you have decided on the population mix for your tank, add them slowly. Bring in one species the first week, another the next until the tank is fully stocked. This will allow the good bacteria in the filter to adjust slowly to the increasing bioload. I have also found that it gives the children time to focus on just that new species; to learn about them and observe their behavior.

These are the basics for setting up a planted community tank in the class room. These directions can, of course, be modified as needed to meet the needs of other types of animals.
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This page was last updated 26 December 1999