Mis-tech

"Mis-Tech." Some tech-inspired fantasies. It's all very easy to chuckle at truly outmoded technology. Sometimes, though, it's more appropriate to marvel. Gunther Sterba's 1967 classic, Aquarium Care, reflected the former German Democratic Republic's madly-unbalanced technology, which was one inspiration for the cult movie Brazil. When the electricity failed in the unregretted old DDR, bicycle-powered generators could keep the aquarium air pumps going. Yet, at the same time, you could have the most beautiful laboratory glass blown for custom-designed undergravel filtration. Sterba's Aquarium Care is an enduring fishkeeping classic, but it's also a monument to the kind of devoted inventiveness that was required for scraping by in unreformed Communist East Germany before unification. Today, fishkeepers in India or Colombia learn to improvise in ways ungrateful American consumers like me fail to realize.
 
But the best examples of what I call Mis-Tech appeal to modern sensibilities in some zany way.
 
Mis-Tech: Aeration. In the 1970s and '80s every fishtank telegraphed its presence with the cozy simmering sound of a kettle of soup. Focus was quite rightly on the aquarium's exchange of atmospheric oxygen and CO₂, but that was thought to be happening on the large interface provided by the stream of bubbles. We tended to ignore some less-obvious benefits. The rising stream of bubbles circulated water at the surface, which continually exposed to the atmosphere water depleted in oxygen or saturated in carbon dioxide. But our imaginations became fixated instead on the size of the bubbles, because geometry showed us that the smaller the sphere, the more surface it had in relation to its volume. Bigger air pumps (the Home Improvement syndrome) were able to force more air through ever more resistant diffuser blocks, to create finer and finer mists of "aerating" bubbles. Naturally the finer diffusers clogged with deposits more rapidly. You could soak them in vinegar, or even buy products marketed to hobbyists for this very purpose. But it was "better" if you replaced them at frequent intervals. You could even buy several diffusers marketed in a pack.
 
The truth was that bubble-powered aeration never "forced" more oxygen into the water, but it did keep the surface moving, where the main transfer of excess carbon dioxide was actually taking place — and it powered the lid of the plastic treasure chest, too.
 
Mis-Tech: Substrate Heating Coils. In 1986 there appeared an English translation of K. Horst and H. Kipper's influential book, The Optimal Aquarium, with its central theme of "optimizing" or "maximizing" the natural cycles that operate in the aquarium. "Optimizing!" That hit a responsive chord in our obsessive American natures. The major technological innovation popularized in The Optimal Aquarium was a system of waterproofed heating coils laid beneath the substrate against the bottom glass of the aquarium.
 
Substrate heating made sense in cool European rooms, where heat radiates away from the glass, and tropical water plants might suffer from "cold feet" and less than satisfactory root growth. But an American lives in a centrally-heated hothouse all winter. In the U.S.A. no one thinks it might be odd or unnatural to keep living areas cooler in the summer and warmer in the winter. "Cold feet" was hard to sell as a genuine problem. Would it have gone better if the "cure" for cold feet were a bottled liquid called "Tropic Toes" or better yet, a pill-like tablet? Unfortunately, the expense of substrate heating cables, together with the foresight required in installing them at the outset, made them a non-starter. Sometimes on planted-tank boards you see a post asking whether it would be possible to install heating cables in tanks that are already up and running. Imagine! Dupla, the company started by Horst and Kipper, makes many genuinely useful products for successful planted aquaria. You can check out the fanciful rationales still offered for substrate heating coils, at George Booth's AquatiConcepts, archived at The Krib. They include imagined "nutrient springs" in tropical waters— a fantasy related to the rich upwellings of cold ocean bottom waters that support the world's great maritime fisheries, e.g. off Peru and in the North Atlantic— and "natural pressure differentials" envisaged in underground aquifers.
 
One useful thought comes out of the substrate heating concept: heat does radiate from your aquarium. This is especially true with an aquarium on an old-fashioned open-bottom wrought-iron stand. (Oh, you don't? ...well, the Skeptical Aquarist still has one!) You can save energy costs by insulating the bottom glass of your tank with a stiff sheet of styrofoam. It would be good to insulate the rear glass too, if doing that didn't interfere with your h.o.t. filters. But if you are even remotely considering undergravel heating, you should already have installed insulation under the tank.
 
Mis-Tech: powerheads and undergravel filters. Powerheads have many appropriate uses in creating currents within the aquarium. Powerheads are essential for the sessile invertebrates in a reef aquarium, for instance. But hooking up a powerhead to an undergravel filter is classic "Mis-Tech."
 
During the 1990s many fishkeepers abandoned the undergravel filter (UGF), which had revolutionized aquariums in the 1970s. They were dissatisfied with the plant growth they felt they were getting with UGF, though some of the hesitations they were expressing seem to have been more conceptual. Jim Kelly says, "I remember someone once saying 'undergravel filters grow beautiful roots and poor plants.' The roots love to respire but many nutrient ions will be oxidized to nonavailable forms with all that well-oxygenated water flowing through the substrate, and the plants will suffer." (You ought to read Jim's good article "Aquarium technology for the very, very budget minded" archived  at the Aquatic Gardeners website.
 
The focus of the UGF became blurred because the system— to the extent that it operated as a filter— had come to be considered as two kinds of filters at once, both as a mechanical filter, which trapped detritus in the gravel, which consequently had to be "vacuumed" out, and at the same time as a "biological filter" for nitrification. These twin filtration aspects got in each other's way, which is not surprising, since any dual-use system can be judged less than optimally efficient, if you are considering an imagined optimum for one aspect at a time.
 
One fan of the self-defeating Reverse-Flow Undergravel Filter (RUGF) saw its aim as "to maintain high aeration of the gravel bed so that its capacity as a biofiltration medium is maximized." For him, the gentle bubble-driven induced percolation of oxygen-laden water full of particulates through the rootzone/gravel bed, which was the original aim of UGFs, got in the way of a perceived "need to keep the gravel bed clear of detritus accumulation." Periodic catastrophic mechanical scouring of the rootzone seemed necessary for "maintaining the gravel bed at maximum potential." The problem in a nutshell: "By and large I suggest that the basic idea of the UGF as a high-efficiency culture medium for aerophilic bacteria conflicts fundamentally with a reducing environment optimal for plants." As indeed it does.
 
If you are going to get the advantages for which the UGF was designed, you need to plant the aquarium densely, so that the gravel develops a densely-interwoven rootzone. You need to refrain from disturbing the gravel, beyond vacuuming detritus from the gravel surface and flushing any detritus that can't be removed up into the water column, so that the filter intake can take it up. You need to begin with a denser substrate than common LFS quarzite gravel, perhaps using a mix of clean construction sand, Flourite, cat litter or peatmoss. I find that as peatmoss slowly breaks down, its mechanical function is gradually assumed by detritus that is converting to compost. At first the peat moss, then the flocs of compost in the substrate capture the nutrients that feed rooted plants.
 
What happens when aggressive vacuuming ("gravel cleaning") scours out areas in the substrate? The flow of water then follows the path of least resistance, and all the flow is restricted to the mechanically scoured area. This may leave other areas of the substrate to become stagnant. The good news is, that a mechanically scoured area will begin to heal itself, as the increased flow means that increased detritus will get deposited among the substrate.
 
A sense of the lengths you may be driven to, in order to combine undergravel filtration with a planted tank can be sensed in a post to AC from Matak, in Ontario, 29 Nov 2002: "I have a heavily planted tank with a RFUGF. Here's the trick: One third of the tank is RFUGF with a foam pre-filter, the other two thirds have a plantable substrate under the gravel. Best of both worlds. Also, my DIY CO2 bubbles feed directly into the tube between the pump and the UGF plate. As far as I can tell, I am getting 100% diffusion of my CO2." Here is a fresh way to use an undergravel filter plate, I thought. In Matak's 30 gallon tank, the single UGF filterplate at one end is covered with regular aquarium gravel at one end of the tank and then an enriched substrate with a gravel top layer, heavily planted, fills the rest of the tank. Then the bubbled CO₂ is carried down the riser tube under the UGF plate and gets pretty completely dissolved in the unplanted section of gravel. And the rooted plants get the benefit of a low-oxygen zone where iron is rendered soluble and phosphate is freed from the substrate.