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an Almost Affordable Aquarium

by Erik Olson
Winter 1993-4


  1. Blurb
  2. The Tank
  3. Modified Dupla Strategry
  4. The Plants
  5. The Fish
  6. Update - October 1994
  7. The Replacement Tank: 1997
  8. Other ventures: The Fish-TV


I've been dabbling in aquariums for a few years now, starting in my college dorm room where I learned how much medication not to add to a tank, why you don't put a Malawian Cichlid and an Oscar in the same aquarium, and how to produce several hundred baby platties with little or no effort. After moving and a year of dry tanks, I decided to try my hand at it once more. A local store had a very good supply of plants, so I foolishly started buying them (and reducing them to melting goo and stumpy remains at roughly the same rate). Then about two years ago, I got my hands on a copy of a home video made by George and Karla Booth where they proudly displayed their four tanks ranging in technology from practically nothing, to an all-out Dupla spendfest. I'll never forget the beginning of that video...There's a shot of this beautiful lush tank with green everywhere, and George's narration: "Well, this is our low-tech tank. Nothing really special; it's your traditional planted tank..." Glancing over at the stumps over in my tank, then looking at the screen & drooling some more, I figured I could probably do a bit better... Since then I've read a lot of plant books, net postings, and grown a lot of different plants (and ticked off several housemates who didn't particularly care for gravel and dirt all over the kitchen or the ever increasing number of fish tanks all over the house). I live alone now. :)

This article describes how I set up my latest tank when I moved. It was an opportune moment since I could set up the new (55 gallon) tank in the new place just before dismantling all my small older ones and be able to move the plants and fish relatively painlessly. Though the final setup was rather quick (all was transferred over the course of a few days), I spent months getting all the pieces together (ordering heating cables from mailorder, getting the tank at a garage sale, and even hunting for laterite along the interstate!)

[PIC]Look for pictures where you see this icon. (This one is a beautiful full-color scan that cost me a bundle. Most of the rest are ugly black and white video transfers.)

Thanks go to George Booth for his Internet postings and valuable suggestions, Uwe Behle for his insight into cable heating and light cycle, Gary Bishop for the do-it-yourself cheapo CO2 controller that I promise someday to build, and zillions of past net postings I've been quietly filing away.


It's an all glass variety, measuring 48"x12"x18". I bought the tank from some guy. He said it was a 55-gallon. When I got it home, I checked the measurements because it seemed a little thin. Turns out, not all 55-gallon tanks are alike! This one's more like 45 gallons. When I move again, I'll probably buy a 80 or 90-gallon for the extra width.

I learned a valuable lesson about stands. For my first two tanks I carefully handcrafted the stands and probably spent $100 in oak alone. What I found was that when I outgrew these things, nobody would buy them for even close to what they were worth. As a result, I have the world's finest oak-encased hospital tank, and I made my new aquarium stand out of $10 worth of 2x4's with some stain & finish slapped on to make it look nice. Even if I don't get the $60 for the tank and stand when I sell it, it won't feel like much of a loss.

Modified Dupla Strategy

The Dupla strategy for planted aquaria is a series of ten criteria which, not surprisingly, can each be met by purchasing one of their exotic and expensive products (see The Optimum Aquarium by Horst and Kipper). In this aquarium, I attempted to follow most of the requirements with inexpensive homebuilt alternatives, and in a few cases experiment with ideas completely counter to the Dupla regiment (but hopefully not so far off base to be classified as "dumb luck"). In a sense, this is an attempt to be the Meister Brau to Dupla's Budweiser ("Works as well, yet costs 1/10 as much!").

I'll go into most of the individual criteria as I've interpreted them below:

Substrate Heating


The main purpose of substrate heating is to induce a slow water current through the gravel. This current draws nutrients and oxygen from the water into the substrate, where they fertilize the roots and keep the area from becoming anaerobic. In a Dupla setup, this is accomplished with low-voltage heating cables buried under the gravel. The temperature is regulated by an expensive controller with an external temperature sensor mounted in the main aquarium. In fact, it is the transformer and controller that make up most of the $450-$700 heating package; alone, the cable only costs $70-$130.

My cost-cutting solution to this was to use the cable as a purely supplemental heater. Conversations with George and Uwe confirmed that it might not be a necessity (or an advantage!) to have the cables supply 100% of a tank's heat. Thus I have split up the job. The main heat for the tank is provided by two 100-watt Ebo-Jaeger submersible heaters. Then I have a Dupla 50-watt undergravel cable that is kept constantly ON. In normal Seattle weather resulting in my apartment kept at 70 degrees or lower, 50 continuous watts is not enough to raise the tank temperature past the low 70's (let alone cook the tank). I may turn off the cable during those three summer weeks when the temperature gets to 80 inside. I bought a 2-amp 24-volt transformer from Radio Shack for $10, and found the housing, fuse, and electrical cords in my electrical junk box. For testing, I used a variable transformer (VARIAC) and slowly increased the voltage up from 12 to 24 volts while monitoring temperatures. (Dan Resler is another netter who has set up a cable system virtually identical to this, and has a much better article on construction of the transformer box.)

The cables must be initially secured to the bottom of the tank. Dupla accomplishes this with suction-cupped cable anchors that can run $100 for the zillions of them you need to buy. I bypassed this with a few strips of acrylic to which I clamped the cables with nylon screws. One problem I noticed was that parts of the cables are in contact with the bottom glass. For best circulation they should probably be slightly elevated into the gravel. Next time I set up a tank, I'll first put in a tiny layer of gravel before laying in the heating cable.


Metal Halide or Fluorescent? I'm still not sure. But I had all the hardware and some of the bulbs to go the fluorescent route, so that's what I use for now.

I wanted this tank to be open at the top, so I built a hanging fixture out of two shoplights. In the past, I've used a "Lights of America" model with lightweight electronic ballasts, mainly because they were the cheapest ($10 for a 4 foot, two tube jobber), but I don't like their annoying habit of buzzing and flickering when starting in a cold room. Luckily, one of our local hardware chains started carrying another variety with the traditional "weighs-a-ton" ballast that is quiet and doesn't flicker.

To construct the hanging "hood", I just screwed the two light fixtures into a (carefully measured!) wooden board and hung the whole mess over the aquarium with two chains. It looks far less tacky than I imagined, and I suppose if I choose to paint the whole thing later it will look almost professional! One thing I worried about was getting strong enough chains and hooks to hold up everything, including those darn ballasts. I now understand the great importance placed on remote ballasts. Next time I will physically separate them from the lighting hoods.

One unexpected advantage of this chain-hung light is that I can raise the fixture onto higher links and still have the lights on when I want to clean the tank. Another advantage is that I have full control over how far the light is from the tank; Currently I keep it around 3 inches above the water.

Woah, almost forgot to mention the lighting itself! I use four Spectralite tubes. They are a full-spectrum fluorescent bulb made by PG&E (I think) and sold for $9 at local co-ops (or $15 at local fish stores).

What is the ideal lighting cycle? I've done well with around 12 hours per day in the past. For this tank I've split the tubes to two separate controllers. One set turns on 1/2 hour before the other and off an hour later, helping to create a "sunrise/sunset" effect. A recent posting by Uwe suggested interruption of the cycle midday (simulating tropical noon storms) might reduce algae (whose condition is light duration-dependent). I have added a semi-random off period at 3 PM that lasts about an hour, and on Tuesdays, the lights are left off entirely. So far, this seems not to affect the plants. Long term effects have yet to be determined.

Water Stability (CO2 injection)

The Dupla regiment calls for Carbon Dioxide (CO2) injection for two purposes, fertilization and pH stabilization (using the carbonate buffer system). The combination of a carbonate salt such as CaCO3 (Calcium Carbonate, or limestone) or NaHCO3 (Sodium Bicarbonate, baking soda), and dissolved CO2, acts as a buffer against pH changes from other sources (fish waste, etc).

Seattle tap water is nearly devoid of dissolved Carbonate salts (hardness < 1 degree), and thus very sensitive to organic acid levels. I add about 1/4 teaspoon of baking soda to every 16 liter "pickle bucket" of water I change, except "topoff" replacement, which is done with straight tapwater. I would use CaCO3, except that the 'chip' form I have them in does not dissolve easily; The baking soda allows precise control over KH. The two most useful test kits I have are a Tetra hardness kit which measures both General (Calcium) Hardness (GH) and Carbonate Hardness (KH), and a low-range pH kit (the Bromethymyl Blue yellow-to-blue kind). I use the KH reading to determine if I'm adding enough baking soda at water changes -- I try for about KH=3-4 degrees. Then I use the pH reading (along with the KH reading) to check the level of CO2. (There is a three-way relationship between pH, KH and CO2 that is well-documented elsewhere.

CO2 is injected from a former keg-tap bottle (free from a friend who had no idea what to do with it), through a regulator ($50, purchased from a beverage supply store) and a Nupro fine-metering needle valve ($40, from Seattle Valve and Fitting), and is injected into the intake of a powerhead. I have found that there is no need to regulate the injection from a pH meter once I have adjusted the needle valve to the right "bubbling rate". However, I do like to monitor the relative CO2 level manually from an over-the-side indicator designed by Gary Bishop as part of a CO2 level regulator. This elegant (and cheap) little device is just a PVC "U" channel glued to a sample jar filled with water and pH indicator, and is functionally equivalent to the expensive continuous CO2 indicators marketed by Dupla and Tetra.


In addition to CO2, Dupla uses a three-part fertilization scheme: Laterite clay in the substrate, tablets added at water changes, and liquid trace elements added daily. The latter two are not particularly expensive (maybe $40 per year), so I buy them.

The imported Sri Lanka laterite clay, however, I find overpriced ($40 for a bag of dirt?!), so I looked for an inexpensive replacement during occasional trips to other areas of the country. According to some sources, any red iron-bearing clay should work equivalently to laterite, but one needs to worry about how much it clouds the water.. One soil that looked promising was found in Huntsville, Alabama (which, I suppose, has something to do with the name REDstone Arsenal, the Army base there). Another sample I found in Lake Shasta, California (near the city of REDding!). The Shasta clay is closest to the Dupla laterite; it does not cloud the water, nor does it easily break up into dust. I added about 1/2 gallon of the crushed clay powder to the lower 1/3 of the substrate (#3 plain-wrap aquarium gravel). Some clay has come up with the roots of plants I've pulled, but it has yet to cloud the water.

Minimum Filtration

I think this is the one major area where I jump away from Dupla, who suggest a wet-dry or similar heavy biological filter to reduce Ammonia (NH4+) waste to Nitrate (NO3-). It has been suggested that plants may prefer to take up their Nitrogen as Ammonia instead of Nitrate, and so a big biofilter will only hinder the fertilization process by getting to the Ammonia before the plants can. This tank has no filter (in the traditional sense), but instead relies on the heavy plant load for nutrient removal.


I built an overflow skimmer/prefilter out of $10 worth of scrap acrylic. I stole the design from a magazine ad and other sources, though I worked out the dimensions myself such that I could use foam pads from an Aquaclear-300 power filter as prefilter pads. (There is nothing worse than having to run around trying to find some oddly-dimensioned piece of open-celled foam!)

The prefilter drains through some PVC pipe, into a 10-gallon glass aquarium ($10) that acts as a sump. In the sump, I have the two Ebo-Jaeger heaters, and a Hagen 802 powerhead ($35 locally) to return the water. CO2 is injected through a vinyl air tube into the intake of the 802. I haven't yet decided what the best return should be; currently I have an end-capped PVC pipe with holes drilled down one side stuck in the tank.

In reality, I did not get away from bio-filtration. I suspect most of the effect is provided by the sponge in the prefilter. In fact, since the sponge is on the average only partly submerged and has water pouring over it constantly, I've realized I have a miniature trickle filter that might be more efficent than a normal submerged sponge filter. This has been evidenced by visible levels of nitrate (which I'm still tracking to get a fix on the cause). I'm torn between leaving it alone (and keeping the extra guard against plant failure) or boiling the sponge to kill the nitrifying bacteria, hopefully giving the plants a better chance.


Here is a drawing of the initial planting plan.

I was strongly motivated by one factor in choosing plants for this aquarium: I wanted to use plants that had worked well for me in the past. This was no problem, because I was simultaneously tearing down my previous three smaller planted tanks while starting this new one. I took my pick of the best plants, and donated (or threw) the rest away. I must admit I haven't paid much attention to the particular biotopes of these plants, so they do come off as a rather mixed group.

One plague that has hit me was an attack of Cyanobacteria (blue-green algae) that quickly covered everything in the tank during the first two months of operation. The plants would still grow well, as evidenced by their appearance when I washed the algae off cuttings, but they immediately grew better and shower brighter colors without the additional "green filter" covering them. The reason it took me two months to extinguish this plague was that the high light intensity made the algae appear bright green instead of the usual dark turquoise, and I mistook it for green algae. Once I figured it out, I dropped in 1/2 dosage of Erithromycin and it was all gone within a week.

Onto the plant species:

Saururus cernuus (Lizard's Tail) [PIC]
Okay, I know it's not really a true aquatic. But I wanted to use Lizard's Tail in that really-cool terraced form as seen in traditional Lieden School Dutch tanks (where it slopes up from front-to-back). They don't sell it locally in Seattle, so I bought some on a trip to Los Angeles and propagated it here. To sprout new plants, you can cut up a rhizome and float the pieces at the top of a hospital tank until new shoots appear. I've also found you can root cuttings easily. Looked stupid and messy until I got enough shoots.
Valisneria sp. "Italian Val". contorta?)
Throws off runners like crazy and grows 3 foot blades that lie across the surface and shade the entire left foreground of the tank. I've also found that it throws up flower stalks when subjected to a change in chemistry. A bunch died when a change in water flow forced the strands to "dive" back into the water; ergo, it likes have the blades partly floating!
Hygrophila corymbosa and salicifolia ("Giant Hygro",Nomaphila stricta)
Used to do real well in tanks without Angelfish, who seem to relish the young shoots. In this tank, they mostly looked like nibbled trunks until one of the Angels died. Now recovering remarkably.
Alternanthera sp. ("Scarlet Temple") [PIC]
Most varieties of Alternanthera seem to have been cultivated emersed. This one seems to be a true underwater specimen. In low light, the tops of the leaves are olive-green, bottoms are bright magenta. With the full compliment of 160W, they are deep magenta and look like the picture on the cover of TOA. Grows out of the tank.
Hygrophila polysperma [PIC]
Grows fast. I sell clippings back to the store. Gets darker with higher light.
Rotala macrantha [PIC]
The most light-sensitive plant in the tank. Also seems to be the most sensitive to Nitrate and CO2 level. Color became red and growth dramatically increased when I added the second light fixture. Also it turns out to be one of the foods of choice when I'm out of town and my friends forget to feed the fish.
Ludwigia repens and "narrow" [PIC] [PIC]
I threw this in as an afterthought. For some reason, it's always been a marginal plant, as well as always having algae attached to it. Luckily, it has been prospering in this aquarium.
Nymphaea sp. ("dwarf lilies", stellata and/or maculata) [PIC]
These have all followed the same pattern in my previous tanks: they get big leaves, the throw out side-bulbs, and then suddenly die off. I have had no leaves on either of the two bulbs since transferring them to the new tank. Nibbled by the fish perhaps?
Barclaya longifolia
Similar effect to the lilies, except that one bulb is showing real signs of life now. It had small stunted growth until the temperature was raised to 77F and the algae plague cured. Now recovering and throwing out new leaves.
Echinodorus paniculatus, small
This is one remaining plantlet of a dozen that survived a red brush algae plague in my old aquarium. It is doing remarkably well in this new tank. I'd say it's tripled in size, but it's still a small plant. I am hoping it will grow and become a shade for the low-light plants.
Anubias barteri, and A. barteri var. nana [PIC]
These were definitely not happy being in direct light in the middle of the tank, since they receive the bulk of the tenacious brush algae. They are also not happy having their new leaves eaten by the Congo tetras. I finally pulled them out and plan to replace them with a light-loving foreground plant like Echinodorus tenellus (pygmy chain sword). My favorite technique of removing tenacious algae from Anubias is to transplant them to an emersed state in another tank (leaves above water) where the algae dries up and can be removed within a month.
Cryptocoryne aff. wendtii [PIC]
I bought these rhizomes when I started with plants almost three years ago. Since then, they have been transplanted, stuck in almost every one of my tanks at one time, and melted leaves countless times. In the old tanks, they've been most succesful when grown in pots, since they do not get uprooted in transport. Nonetheless, I planted these directly in the substrate. They are showing really exceptionally full and tall growth, much better than in my non-CO2 tanks.

Fish (as of March 1994)


As mentioned before, I felt like kicking myself for ignoring Dupla's "initial break-in for Algae" period. They suggest keeping (and not feeding) black mollies to control the initial plagues of algae that may set in. Unfortunatly, I was coordinating the setup of this tank with moving, and needed to move some of my old fish into the new aquarium. I have paid for this in extra water change & treatment hassles!

The fish are composed of two groups: The decorative and showy things I planned to keep, and nearly every algae eater known to mankind (the latter purchased for other tanks during previous algae attacks).


Phaenecogrammus interruptus (Congo Tetra) - 6 male, 1 female.
Originally purchased at the $5 level, they've now grown to the $15 level. I've never had one of these die on me in the normal way; instead they get caught in the skimmer box and die of starvation when I'm out of town.
Pterophylum scalare (Angelfish) - one.
From previous tank.
Pelvicachromis pulcher (Kribensis) - two male, one female [PIC]
Learned how to sex them shortly after buying three males. After an exhaustive search, I got one female from a local guy with plenty to spare, and they eventually spawned.
Crenicara maculata (checkerboard cichlid) - three., one... no, two... no, one. I exchanged some plant cuttings for four of these somewhat expensive fish. I left town for two weeks (can you see a pattern developing?) and only one was there when I got back. Purchased two more with more cuttings. They all did great until I bought another (male) from a diseased tank. Back to the original one (sigh).

Algae Crew

Otocinclus sp. - six?.
They seem well-fed. They also seem to enjoy getting caught in the surface skimmer/prefilter trap. Unlike the Congo Tetras, though, they can survive in there for weeks on the plant leavings that get caught in the skimmer.
Epalzeorhynchus sp. ("Thai" flying fox or false siamensis) - two.
Maybe they're eating algae. Maybe they're not. At least they aren't beating up the other fish.
"Malasian Sucker" - two.
These guys look sort of like C. siamensis, the amazing Siamese Algae Eaters that are supposed to do wonders for red brush algae. But the guys at the store had no idea what their true name was, and couldn't find "Malasian sucker" in the atlas. They do seem to root around in brush algae, and in this new tank the brush algae is limited to little spots on the glass.
Some algae eaters I've used in the past and might again if I get desparate:
Plec*stomus - A bit harsh on plants, but happy if you give it wood to chew on. Peckoltia - Not as harsh as the pl*co, but the last one I had rasped all my broad-leaved plants to death. Farlowella - Seems to be very effective against algae, but also somewhat delicate; I had two die on me.
Erik Olson

[Look! Here's an October 1994 update with more pictures!]
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