hmmm, well to me low tech is
Diana Walstad's method. A nutritious substrate, natural sunlight, fishfood/mulm feeds the plants, no water ferts, and sunlight combined with moderate lighting. In this type of tank, the plants are the water purifiers rather than the usual filters. Diana says the goal is to set up an ecosystem where "plants and fish balance each other's needs". The only downside I've seen so far is that you can't move plants with large root systems easily and you can't have fish that like to dig or that move a lot of gravel. Other than that, it's a great low hassle approach that results in very happy plants wiithout a lot of tinkering. Here's the progression of my
125 natural planted tank and my
30 gallon bowfront.
High tech usually involves a not so nutritious substrate, dosing with ferts to compensate for the substrate, high lighting and CO2 injection. The emphasis in these types of tank appears to be the plants and aquascaping with the fish being ornaments to complement the aquascaping. These are great if you like to tinker and mess around with the tank constantly.