Eco-complete is pretty comparable to normal aquarium gravel size wise. Depending if you want a flat coverage or some mounds you could use the standard gravel pound for gallon. Just a warning this stuff can cloud the tank for a few days if you aren't careful. I made the mistake of adding with the tank most of the way full and it took a couple days to settle enough to see in the tank even with some water changes.
a way to keep the clouding under control when filling a tank is to use a cup and a plate. stack the cup on top of the plate and put in on the substrate and fill the water into the cup and let it overflow into the tank
Thats a good idea ive used the plate before but not the cup
Can you use pine for wood? I just came back from the dump,and there was abunch of clearing done there years ago and i noticed all the upturned roots all bleached out grabbed a few and tossed them in my truck but not sure if they could be used in my tank the are black spuce to be specific.
Usually people who use soft woods like pine/cedar/spruce make sure it is old. I'm not sure about pine and spruce but cedar has natural chemical in it that repels bugs and can be harmful to fish. However if its aged those chemicals will be weathered out and no longer an issue. If the cedar still has a "cedar" smell then you probably shouldn't use it. Not sure if spruce is the same way though.
Softwood might breakdown faster than a piece of hardwood like oak.