I also have read the books, but come on guys stop spoiling it for people who haven't read them or watched the series yet.
Either that or I will pm you with all the major plots and ruin it for yous.
As long as you cap it with a couple of cm of sand you should be fine, or you could get some nutrient hungry plants like duckweed, water fern etc. to suck up the excess nutrients from the water column.
As long as you don't stock it with fish that like to dig you should be sweet, also planting your plants before you add water will help to keep the water from initially going really cloudy.