I'm using sandy river silt for my tank, and have done so in the past, with great results. But, if your soil is mostly sand, and mica, which the gold specks probably are, it isn't likely to be very good. Look for soil under trees, where the fallen leaves have composted in place, giving a rich humus layer on top.
"Normal soil" could mean a lot of things. If you use mineralized topsoil, capped with something like Flourite, it should last as a nutrient filled substrate for more than a year, probably 2 years or more. It is always desirable to fertilize the water even when you have a fertile substrate. That gives the plants two sources of food and lets you be a little careless about dosing the water. But, with low light, you can do without the water dosing and just rely on the substrate.
Watts are irrelevant when determining how much light you will have. Instead, you need to consider what type of light you are using, T5HO, T5NO, T8, PC, etc, and how far the light will be from the substrate, where the intensity is the lowest. Within each type of light, the wattage just indicates how long the bulb is, thus, how long a tank it will light uniformly.
My husband did have a question with the Coralife 2 bulb T5NO light, he was wondering if it's enough wattage for a 55 gallon tank. Here is the link you sent. . .thanks! Question was regarding an Amazon Biotope aquarium set-up.
Hi Hoppy, I am new to the forum and just posted a discussion for my planted 75 gallon, I have been having some problems with growth and was wondering if you would be able to take a look and provide me with some feedback on lighting? I hear you are the king of lighting planted tanks so any advice you can give me would be great!