Reading recent threads about mineralized top soil (MTS) I was thinking of updating the tutorial with a simple introduction, just as a reference; let me know what you think...
Mineralised Top Soil
An alternative to allowing soil to mineralise in situ is the use of MTS (mineralised top soil) or mineralised potting compost. MTS is thought to bind more bioavailable nutrients, and give your plants a better start whilst preventing the excessive release of organic nutrients. Excessive organic nutrient release combined with too much light, can lead to algal outbreaks. Further, MTS is often considered less prone to disturbance during scaping and subsequent maintenance. The internet provides a wealth of information on how to mineralise soil, but the methodology after Aaron Talbot is perhaps the most widely used. It simply involves a process of repeated soaking, rinsing and drying, typically four cycles long. Eventually, the soil is sifted to remove large particles and achieve a fine grained well sorted substrate.
Finally, powdered clay can be added. Its flocculating properties help bind the soil particles and its high CEC and iron content benefit plant growth. Powdered or pelleted Dolomite can also be added as a source of the nutrients magnesium and calcium, and if necessary to buffer pH, and similarly potash can be added as a source of potassium. However, mineralising soil is a lot of messy work, and on balance I prefer to do it in situ, mainly because it's far less labour intensive but also because of the synergistic benefits already discussed further above. Not least of these is the evolution of CO2 as the organic matter in the soil decomposes, and as also previously mentioned, it’s a convenient way to cycle a tank.