If you haven't already, read this
While those tanks are impressive, they're hard to copy. I would start with something more basic, like these
Iwagumi sounds simple, but you must have good rocks or it doesn't work very well. You'll also need fish that don't mind swimming out in the open. And it works best in short, long tanks. A 29g would probably end up looking empty.
Sorry to hijack this thread. I'm planning to fill up my tank with subtrate and looking to do some high slopes towards the back and sides. My question is how do hobbyist generally keep the soil gradiant intact, ie how do i prevent the soil from sliding down in due time? Will the roots of the plants hold them firm, or i need to put something in the soil to hold up? Can't seem to find any tips on this.
If the slope is very steep, people usually use rocks or wood to keep it from settling. If it's a gentle slope, just making it a little steeper than you want it at the beginning and then putting it back if it settles will do the trick.
If you need more info you should start a new thread.