Low light low tech planted tanks are ideally suited for beginners or those hobbyists who would rather not spend lots of time maintaining their tanks. Growth is slow and for the most part when the tank is "balanced" the aquascape remains static for long periods of time, unlike the High light high tech tank that changes from week to week with lots of nutrient additions and pruning of rapid growth.
Low tech tanks are generally meant as tanks with low light and no CO2 injection. To create a successful low tech tank there are some items that from my experiences have been critical for success.
Begin with 1 to 2 watts per gallon of linear normal output fluorescent lighting. This usually equates to two lamps (Bulbs). You don't need to purchase expensive aquaria specific bulbs, just choose bulbs with a color rating between 5000K and 10000K, my preference is to mix 6500K and 9325K bulbs when ever possible. Next, choose a "rich" substrate. Plain gravel is a poor choice in my experience. You can use plain gravel but mix in a few handfuls of ground peat and some laterite. Laterite is an iron rich clay substrate that can be purchased from your local fish store or online. Other combinations of substrate materials can be used also but always add the peat in addition to the sand, Flourite, or other material. Ideally if you have an already established tank adding some mulm from that tanks substrate really helps a new tank. Substrate depth should be 3-5 inches deep. Make sure you locate the peat and laterite in the bottom 1/3 of the substrate.
Use any style filter even bio-wheel filters are fine since we arenít trying to inject CO2. Bio-wheelís wonít cause a loss of CO2 in a non injected tank. Donít use undergravel filters though. Plant very heavily right from the start making 75% of the plants fast growing stem plants. Adding some floating hornwort or similar is also very beneficial at the start, just limit the surface coverage to 20%. Stock with small fish and a low number for the first 3-4 months, but always try to keep a low fish load in a low tech planted tank. Itís a good idea to have an algae cleanup crew consisting of any one or a combination of the following; Siamese Algae Eater (SAE), Amano or Cherry Shrimp, Otocinclus (Otos catfish), American Flag or Florida Flag Fish, and Rosey Barbs.
Hereís the part that makes most people cringe. Leave it alone. No water changes, no fertilizer. Only add tap water weekly or as needed to top off the tank due to evaporation. If your plants show signs of nutrient deficiencies such as yellow leaves or holes in the leaves you can add a Comprehensive fertilizer such as Flourish or Tropica Master Grow once a week until improvement is noticed then only add it once a month thereafter. Limit water changes to times immediately after youíve uprooted plants or done a major pruning. Personally I change water in my low tech tanks about once every 3-4 month at pruning/replanting time.
If you can leave the tank alone it will not disappoint you. The more you dabble with this type tank the more likely youíll upset the balance and algal problems will appear. If this approach seems too tame and you desire more involvement then you should consider the high light CO2 injected tank.