07-22-2011, 07:51 PM
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Originally Posted by EireBelle
I hope you don't mind if I hijack your thread for a moment; Since we are talking about preference for substrates, do you ever mix different substrates? For example, say an inch of flourite or eco-complete on the bottom (approx 1 inch) and a layer of gravel or sand above (approx 1-2 in) it? Comments, thoughts, criticisms?
This can work but it also often fails, from an appearance perspective. As far as plant growth, there is less impact except with respect to the grain size.
Taking the last point first, plants grow best in a fine gravel (1-2 mm grain size) or coarse sand. Enriched substrates are mainly either of these because they work. Too large a gravel can be problematic for anchoring plants, root and runner development, and perhaps more importantly as a healthy bed for organics and bacteria. This latter involves water circulation through the substrate, plus the holding and breaking down of organics by snails and bacteria working with plant roots, and both need time to do this.
To the former point, substrates will mix if they are layered with different types. The water flow throughout the substrate achieves this, some fish may help out, and plant roots and snails contribute too. Finer grains will settled to the bottom, larger on top. If the substrates are different in colour, this may or may not end up looking nice. "Natural" is not likely, if that is an aim.