Hi, mate
you can bury some of the rocks if it too big in the substrate. The classical iwagumi has odd number of stones each has some name. For good balance and depth of the skape use the rule of thirds or the golden proportion. Where the biggest rock should be off the center and the second big rock it is "counterweight" in the scape is on the opposite side. the third supporting visually the first and s.o.
http://www.thegreenmachineonline.com...s-introduction
Looking forward for update
Kind Regards