Well, I'm running Eco Complete in my 4 (edited, forgot about my 2 10G tanks with eco) planted tanks (using over 300lbs of Eco, 16 bags total between 4 tanks). Yes, it is is part gravel and part sand, and you do not deep gravel vac it. By doing so you will remove all the good fine Eco that helps the plant roots stay in place. With Eco complete, you only suction off the top of the Eco by waving the gravel vac over the surface and sucking up any loose crud. So I completely agree with Mr. Funktastic, he has it absolutely correct. And as for the specs, I have not seen the specs that were given above. My Eco contains grains that are like dust (much finer than the pool filter sand I have in my 55G) all the way up to gravel almost as big as aquarium gravel. And that is another reason you don't rinse Eco before adding to the tank. MTS is an excellent addition to any planted tank, as they will keep the gravel churned, and don't give the tank an eye sore like other snails do. Usually they are under the gravel, with an occasional appearance. And they don't eat plants either.