Plants in a Coldwater Tank

A lush, green, full Garden of Eden unfolds before you. Placidly, gingerly swaying in the gentle, cool currents, green stems abundant with greener leaves open, filling the panorama.

A lush, green, full Garden of Eden unfolds before you. Placidly, gingerly swaying in the gentle, cool currents, green stems abundant with greener leaves open, filling the panorama. Twisting, turning, intertwining trunks tower upwards. Slipping through the massing strands of green, their colourful bars providing perfect camouflage, a group of beautiful cardinal tetras swims, shoaling peacefully amongst the fronds. The almost tea-coloured water and green background brings out every line in their pattern like never before. Meanwhile, a bright yellow Nannacara female escorts her brood tenderly through the foliage, a shoal of pygmy Corydoras, small and meek, swim comfortably among the blades.

This underwater jungle is not beneath the flows of some abstract tropical stream, but in a glass box atop a dresser. This is a small, twenty-gallon, garden. It is home to almost a dozen plant species, each holding its own niche, and several fishes. The fish are less important than the plants, providing food and carbon dioxide for the plants and breaking the monotony of the gentle sways. Nonetheless, they are a fascinating, beautiful part of the aquarium. Plants overtaking fish in the priorities of the aquarium is the essence of the Dutch Aquarium; Ironically, my fish have never been healthier since they have become the background decoration, nor the plants since they have become the focus.

My interest in planted aquaria grew out of a desire to create a more natural setting. I had been working with ways to minimise filtration. I also wish to minimise the absurdly unnatural amounts of nitrate and other biological wastes not handled by conventional filtration. Typically, water changes manage these. However, water sources are often rather high in nitrate, as well as phosphates. Moreover, I had some new and unusual dwarf fishes I wished to display at their best, and possibly breed. These include an unidentified pair of Apistogramma, a pure white pair of A. cacatuoides, Amandae Fire Tetras, and several others.

I decided to do away with the plastic plants in my aquarium, and replace them with live ones. The fish really did not seem to care at first. Then I ran into every planted-tank keeper’s three worse nightmares. The plants turned to mush, the water turned quite green, and I lost several fish.

My original plant choices were typical. I chose plants that looked like what I envisioned water plants to look like, lots of stems with little leaflets all over them. These plants were cheap, and came in bunches, so I got many of them for one low price. Fortunately, I avoided a more classical mistake, and did not plant them in bunches. Each stem was given its own spot in the gravel bed. This was perhaps my only right move.

The plants I chose, Elodea and Hornwort, are typical culprits for these problems, and probably responsible for driving more would-be plant keepers back to plastic than any other. Their tiny leaves, which I once found so attractive, often drop off when first planted. Like most people, I had added additional lighting to the tank to help the plants. The decomposing leaves provided a perfect source of nutrients. The added light cinched it, and an alga bloom occurred. The algae began producing toxins, limited available oxygen, and died off, adding more nutrients to the water. Culminated, these did in some of the fish, which naturally only helped this vicious cycle even more. far from the peaceful serenity I had envisioned.

Far be it for me to give up. . . . If I didn’t like challenges, I?d keep goldfish! I stopped, and re-evaluated what I had done, examining my mistakes. Then, I tried again. For my second try, I decided to try some low-light plants for the first tier. With any luck, this would minimise the algae bloom, since less light would be used. Most people recommend planting heavily from the start, which is sound advice. Recently, one of my plant tanks suffered a minor disaster — it was left in the care of someone else for several weeks, during which it turned to a pool of slime. I was forced to restock it at once, having to move in a few more weeks. The entire venture cost eighty dollars, and that was not even a full restock. For this reason, I find it more realistic to stock gradually, despite the problems it may cause.

The plants chosen were primarily Cryptocornes. These are broad-leaved, shade loving, variable plants. Typically, they are seen in black plastic pots filled with an itchy fibrous material. There are three very good reasons for removing both the pots and potting: one, plants just plain grown and do better in the gravel bed than in the fibre. Two, the fibre may be hazardous to the occupants of the tank. It certainly is to my skin! Last, and more importantly, there most likely are multiple plants in the pot. Many of these pots had as many as six plants in the basket. At five dollars a basket, that works out to eighty-three cents each, cheaper than a bunch of Elodea, and a fairer choice.

The Crypts were planted each in the gravel bed. As the tank had contained fish, and the gravel already contained a light amount of peat moss, mulm in the gravel was not an issue. For fresher tanks, I have used laterite with great success and would greatly recommend it.

As the Crypts grew and spread, other broad leaf plants were added. If leaves died, these were easily removed. Damaged leave and stalks were readily culled before planting. Of course, this was minimised as the plants were much simpler to inspect prior to purchasing than finer leafed choices. Plants such as Amazon Swords, Melon Swords, and so forth were added for the second tier. These plants are far from shade lovers. However, they did well in the water with the tanks traditional lighting. As they grew and took root, the lighting was increased. A minor alga bloom occurred. However, this one was much smaller than the first, and easily handled by increased water changes.

Later, other plants were added. These, too, were broad leafed, more a function of tastes than anything else. Java Fern, also bought planted and separated into well over a dozen plants, was the next addition.

At this point, I had a tank full of larger, broad leafed plants. The fishes were quite happy, and began to show preference for the livening, growing forest about them over the plastic jungle they previously enjoyed. At this point, I had quite a mass of plants filtering the water. Moreover, some of the fishes had begun picking at the leaves and stems, as well as the algae that grew over them. The fish were getting a more natural food, and their water had begun to become cleaner, more natural. Unfortunately, I was not happy just yet.

I had a well-scaped tank, full of broad-leafed plants. It just did not look as nice as I thought it could. The larger amazon sword had begun to grow outwards, coming to dominate the tank. Most of the aquascaping was low, but very full and quite attractive. But, it could still be better. Therefore, I began adding some taller plants. Red Ludwiga was planted intermittently throughout the tank. It quickly began to multiply, filling out the tank. Three types of Hygrophilia were added, Jungle, Giant, and normal Green Hygro. The Jungle Hygro rapidly grew upwards, breaking through the surface of the water. The Giant and Green grew throughout the tank, easily being trimmed down to create multiple plants. These grew and filled out the tank. Within a few weeks, the tank began to take on a much more pleasant look. Other bunch plants were gradually added, including pond penny and Elodea. The Elodea, unsurprisingly, did not make it very long. The other bunch plants were rapidly able to outcompete it. Its fragile leaves became damaged by the fishes, and the plant eventually dwindled downward. The entire tank bottom was rapidly covered with plants.

Occasionally I removed various plants for one reason or another. They were either becoming too dominant, overtaking ones I wished to keep growing, or beginning to die off. The Cryptocorne began to go through a cycle. Every so often, it would be completely outcompeted, and die off. Small leaves would then struggle up through the gravel in new areas, flocking up a new stand. Eventually, they found spots to their liking in the tank, and became stable there.

I have always been active in the Native Fish branch of the hobby. I am frequently found waste deep in some swift moving stream or remote pond searching for one of our native jewels or another. This offered a great opportunity to me; I became able to collect some of my own native plants. Milfoil, a common pest plant in many ponds, was the first plant I found. Eel grasses, fairy hair grasses, small lilies, Cabomba, and several other natives or introduced plants I have never been able to identify found their ways into either my planted tank, or others.

Plants are readily collected. Many stem-centred plants, like the Elodea, Cabomba, and so on, were readily collected simply by breaking them off in the water. The bottom is then stuck in the gravel, quickly taking root. Other root-based ones, such as Eel Grass or Lily?s, are more difficult to collect. Occasionally, they can be found, in smaller forms, floating in dense patches. These were either displaced by an animal, or simply runners that have broken free prior to taking root. If not, they are simply dug up in shallow and replanted at home. It’s important to take fewer of these than stem-based plants. It’s unlikely that any one collector is likely to damage a group of these. However, a bottom of a lake torn bare in one spot with earth and stones displaced looks quite ugly. These plants also reproduce more slowly, requiring more time to recover.

All plants, regardless of origin, though especially the ?wild caught? ones, are well cleaned before planting. This typically consists of running them under tap water until they are relatively clean, removing any visible problems, such as snails, planarians, and so on as I am going along. Generally, I have found that a tap water rinse is adequate, though for especially soiled or problematic plants, I will typically use a potassium permanganate solution. This is either available from a chemist, or in some medications in one form or another. It also has the added advantage of killing off protist and bacteria, including algae and cyanobacteria, as well as the wealth of animal life likely to lurk.

The fish have become happier ever since I have changed over to the planted aquaria. The only filtration in the tank is an undergravel filter with powerhead. With the varying thickness of the gravel bed, and density of roots in it, the filter is hardly doing much beyond moving water. The plants are the primary filtration for the tank.

Water changes, something I wished to minimise, have become more important than when the tank was fish only. Despite the heavy plantings, there is still plenty of nutrition available for algae. Given the heavy lighting, nutrients must be kept in cheque by water changes to prevent small blooms. These blooms are no longer flagellate algae in the water, but cyanobacteria in the gravel bed and against the glass. The bacteria are also left uneaten by the Ottocinclus in the tank, wisely so. Cyanobacteria, or blue green ?algae? produce a number of various toxins. Some of these toxins are strong enough to kill an adult human in even small doses! Fortunately, the algae seldom release these toxins into the water in significant doses, nor do we frequently get the proper types of algae to kill ourselves. This problem is best dealt with by keeping the plants growing strongly and heavily, keeping up with water changes, and manually removing the algae if it does become a problem.

I have only run into two other serious problems that affect the fishes, both related. One is heat, and the other low oxygen content. Fluorescent full spectrum or plant lights are relatively inexpensive and the best bet for growing plants. However, two watts per gallon tend to heat the water a bit. In a larger tank, this probably would not be an issue. In my smaller plant tanks, the water warms rapidly. The heated water holds less oxygen than cooler water. Therefore, I have chosen to add additional lighting and keep the bulbs higher above the tank.

Almost two years later, I have let my first plant tank reach its own equilibrium. Aside from the water changes, turning the lights on, occasionally removing algae, and feeding the fish, there has very little maintenance for the tank. The tank, even with my relatively slow addition of plants, was able to reach an equilibrium in a matter of months. I have moved on to planting my other tanks.

Now, I have an underwater garden, growing peacefully and serenely. The tetras swim placidly, occasionally even laying eggs. The Otocinclus have bred countless times, and the Nannacara still spawns regularly.

by Bill Duzen

Article compliments of Native Fish Conservancy