Originally Posted by BTLee
First of all, thanks for sharing such an informative article on the subject.
In fact your article was quoted in a Malaysian based Planted Tank forum and it has attracted a lot of attention and encouraged many to try out the said process.
I have a some related questions on the subject of DIY substrate and I hope your experience will be helpful.
In my locality, laterite ( locally called 'red earth' and which I belief is the Clay you mentioned ) is readily available.
A few of the local hobbyist including me is also toying with the idea of using this laterite as the primary substrate for our planted tank.
What do you think, if we mix this laterite ( without top soil ) with some fine gravel/course sand and use the mixture as the bottom substrate then, ( to prevent excessive clouding of water ), top this bottom substrate with another layer of pure fine gravel/course sand.
I also assume that using this laterite, we do not have to mineralize it the way we use top soil instead.
Your comment and recommendation is highly appreciated.
That's neat to know it's spread globally. Again though, it was never my idea to begin with. I just wrote the article. The idea was first introduced to me by a friend of mine in my local club.
The laterite is an excellent substitute for the clay in the minerzalized soil "recipe." However, it doesn't have the nutrients that the topsoil does. Also using too much clay has been known to cause cloudy water and algae issues. You just want the soil to have a 5-10% clay content. It's just enough to provide good flocculation to allow the soil to settle out of suspension when plants are moved around and to bind nutrients in the soil.
Is topsoil hard to find or expensive? I just buy my topsoil for about $2.00 USD / bag.