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Water Changes

We are doing weekly partial water changes of 100 liters (1/3 the water volume). For the water change, we turn off the trickle filter and let water run back into it until its siphon breaks. We then attach a homemade plastic gauge marked in 25 liter increments to mark the aquarium water level. The gauge is calibrated in liters, since the Dupla additives are all dosed in terms of liters of water. This allows use to change exactly 100 liters and refill the tank to the correct level.

Before we drain any water, the pH and ORP electrodes are moved to the skimmer box so that they can remain submersed in water. If they become dry, it shortens their useful life and requires some time to equilibrate after they are put back in the water.

A Python "No Spill" gravel cleaner is used to drain the water to the outside house shrubbery. The top of the gravel in and around plants is lightly suctioned to remove excess detritis. Since there is no under gravel filter, debris is not pulled into the gravel and it is much easier to clean.

After draining, the Python is then attached to the kitchen faucet for refilling. We stuck a small Second Nature liquid crystal thermometer permanently on the faucet, which allows us to set the temperature at the faucet without running back and forth to the tank to feel the temperature of the water. This is a very useful thermometer because it has a moving line to indicate the temperature rather than numbers in different colors which hard to interpret. it also is very accurate and responds to water temperature changes quickly since it stuck on the metal faucet.

The recommended amount (50 ml) of Duplagan water conditioner is added to the tank before refilling commences. Prior to refilling, we run the tap water for a minute to make sure there is no dissolved copper in it from the plumbing. We use the water directly from the faucet and do not use any dechlorinator. Any chlorine in the water apparently does no harm to the fish, as the discus in the AOA show no ill effects and one of the pairs is currently raising a small group of fry in the tank. We know that our tap water contains only gaseous chlorine and no chloramines. We think the low levels of chlorine in our tap water may act as a mild anti-bacterial agent and helps maintain a healthy tank.

One Duplaplant tablet is added to the prefilter box of the trickle filter. This is one-half the recommended dose, but based on experience, provides the correct levels or iron. Adding the tablet to the skimmer box lets it slowly dissolve and get dispersed evenly throughout the tank and prevents the fish from trying to nibble on it. The tablet adds enough trace elements to nurish the plants until the next water change. Also, enough iron is added to last for 2 days before Duplaplant 24 drops are used.

Since our tap water is very soft, we must add some hardeners at each water change to maintain our desired carbonate hardness (KH) and general hardness (GH). One teaspoon (about 6 grams) of sodium bicarbonate (NaHCO3) per 50 liters of water will increase KH by 4 degrees and will not increase general hardness. Two teaspoons (about 4 grams) of calcium carbonate (CaCO3) per 50 liters of water will increase both KH and GH by 4 degrees. Different proportions of each can be used to get the correct KH/GH balance dictated by the fish and plants in the tank. Since it is difficult to accurately measure small quantities of dry chemicals at home, a test kit should be used to verify the actual KH and GH that is achieved.

We use ACS (American Chemical Society) grade chemicals bought in bulk from Hach Chemical to ensure that there are no contaminants added to the water. After a water change in the SST (100 liters), we add 1 teaspoon of sodium bicarbonate and 2 teaspoons of calcium carbonate to maintain the KH at 4.5 and the GH at 3.0. The hardeners are also added to the skimmer box to prevent the fish from trying to eat them.

During the weekly water change, plants are trimmed if necessary, and any dead or dying leaves are removed. The slots of the overflow box are scrubbed with a small brush to remove any algae build up that would prevent full water flow. The inside walls of the tank are scrubbed to remove film and any algae spots. Filter pads in the trickle filter are checked and changed if needed.

Water Chemistry

During the initial break-in period, the ammonia and nitrite levels were monitored closely. No sharp peaks were seen in either parameter, because the fish load was light and the fish were only eating algae. After three weeks fish other than algae-eaters were added slowly and ammonia and nitrite levels were monitored. Nitrate levels are monitored to determine if the partial water changes are sufficient to keep a low nitrate level so as to not encourage excess algae growth. Through water changes and careful feeding, we strive to maintain nitrate levels less than 10 ppm. Currently, the AOA runs between 4 and 8 ppm of nitrate.

Phosphate levels are monitored periodically for the same reason and also to give us an idea if we are overfeeding the fish. Phosphate levels are kept below 0.1 ppm.

With the Sandpoint II controller and a solenoid valve, manual CO2 and pH checks are kept to a minimum. As for hardness, first we established how much calcium carbonate and soldium bicarbonate were required with each water change to maintain a general hardness of 2 degrees and a carbonate hardness of 4.5 degreees in the tank. KH and GH are monitored periodically to determine that nothing substantial has changed in our water supply. As long as the KH is constant, CO2 will be injected automatically to maintain the set pH of 6.9.

Filter Maintenance

With the top of the aquarium open, evaporation is a concern, especially in our low humidity climate. We find that about one and one-half gallons of water evaporates per day. With a trickle filter, the water level in the tank remains constant and the loss of water is accounted for in the filter sump. Since the filter is fairly small, we must make up for the water loss daily or the pump will run dry.

To indicate how much water is needed, a piece of white plastic tape is affixed to the side of the filter and is marked in gallons. "0" is at the low water mark (just before the pump will start sucking air) and 3 gallons are as much as we want to add to prevent the bio-media from being submerged. We try to keep the level between 1 and 2.5 gallons above the low water mark. Two 1 gallon plastic jugs are kept filled with water whith which to refill the tank. The water is added directly to the tank.

The polyester pads wrapped around the prefilter sponge and on top of the drip plate are replaced with clean ones on a regular basis. Dirty filter pads will reduce the water flow in the system, reducing the filter efficiency. Pads clogged with decomposing debris will also contribute to higher nitrates. The ORP reading is a good indication of filter condition - the value starts to drop when the pads are dirty enough to affect the water quality.

The pad wrapped around the prefilter sponge is changed twice a week. This collects the most debris, usually dead leaves and food particles. The drip plate pad is changed once per week, usually during a water change. The dirty pads are rinsed with water and then soaked in a 20% bleach solution overnight. The following day they are rinsed extensively and dried before reuse. We have a good supply of filter pads that are rotated on a continuous basis.


The quality and intensity of light in a planted tank is very important. To maintain the best light possible, bulbs are changed on a regular basis. Most sources state that the useful life of a fluorescent bulb is about 6 months. After this point, the intensity has degraded to about 70% of its initial value. We mark all our bulbs with the date they are first used and change them 6 months after that date. We make sure to not change all the bulbs at once, since if all the bulbs were on the same cycle, the tank would be starving for light at the end of a six month period. One bulb is changed roughly every 2 months, giving us a high average intensity.

Metal halide bulbs are much longer lived than fluorescent bulbs, which is a good thing since they are quite a bit more expensive. Most sources say that 12-18 months is the expected useful life of a MH bulb. We will check our occasionally with a lux meter to determine when it is time for a new bulb. Initially, the MH bulbs provide 35,000 Lux at the bottom of the light fixture, 4200 Lux at the water surface and 1400 Lux 4" from the bottom.

Approximately every two months the pH and ORP electrodes are removed for an extensive cleaning according to the manufacturers directions. Between times the electrodes are just cleaned of algae if necessary.

The probe used on the pH controller must be calibrated periodically to maintain its accuracy. This a fairly simple half hour procedure that we do every two months or so. The probe does wear out, so it also must be replaced about every 18 months or when the readings become erratic or it is difficult to calibrate. Since the pH contoller is a critical part of the aquarium system, we keep a spare probe around in case we should accidently break the one in use.

There are no adjustments on the temperature controller, but we do check it against a lab thermometer, just in case.

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This page was last updated 21 February 1999