One of the biggest headaches for planted tank enthusiasts is choosing the right substrate. There is no 'best' substrate as each has advantages and disadvantages. So let's take a look at what is available.
NATURAL SAND AND GRAVEL
Inert sand and gravel can make a perfectly good starting point for any aquarist. My favourite quartz sand is from the Nepean River. Never use beach sand, always river sand. Fine rooted plants like Hc and Hairgrass will grow easily in sand. Their roots are able to make a tight grip in sand and in nature, they are usually found growing on the fine, silty edges of creeks and pools.
When choosing a gravel, go for a grain size around 2-4mm as this will allow roots to grow freely and also allow water to circulate through the root zone.
Quartz gravel is a good choice for people wanting to use Undergravel filters as it will not break down over time and clog the filter. Baby fish and shrimp will not get caught in these filters and cleaning with a gravel filter then topping with clean water achieves a water change and filter clean at the same time. Amendments such as Laterite are also suitable to provide food directly to the roots. The addition of Marble Chip will help avoid problems with Vallisneria, Swordplants, Aponogetons and most of the Cryptocorynes.
If you are planning to use only Mosses and Ferns, Natural Gravel is possibly the best choice.
These are designed to provide a good media for heavily planted tanks. When you choose a brand of soil, I suggest you stick with the same brand of amendments and fertilizers since these are designed to compliment the substrate. People using these substrates will often spend a lot of time dosing, testing and adjusting their tanks. Good lighting and CO2 injection are necessary to achieve the best results.
Many people these days like to mix their own substrates. Diana Walstad has written articles and books with her findings on home made mixes. Well worth reading her material if you want to have a go. There is also a trend for some of the better aquarium outlets to provide their own specialty mix.
One of these is SMARTSOIL, designed by aquarists to make planted tanks easy. SMARTSOIL will help prevent ammonia spike during set-up and contains a flocculant to avoid cloudy water when disturbing the substrate.
I welcome comments and positive input to the comments I have made here.