Larger gravel does not absolutely have to be round edged, although I prefer round edged gravel for bass spawning. I am not sure that the bass care. Two local ponds have golf ball sized crushed limestones ("1"-3" pieces) lining the bank and crushed fine limestone (1/8"-1/4") on the beach area. SMB in these two ponds routinely have hatches each year. The benefit to round river gravel is that it may stay cleaner with less attached algae growths than the limestones. But when the bass gets to cleaning the nest most loose debris gets brushed away.
More important than the shape or surface texture of the coarse gravel for bass (SMB) spawning, is to locate some sort of piece of structure adjacent to the nest such as a log, small cinder block wall, large boulder. Studies have shown that at least SMB prefer some sort of structure adjacent to the nest site. It is thought that the structure makes it easier for the bass to defend the nest against intruders. Defending two or three sides of a nest is easier (more successful) than defending a compeltely open nest that is vulnerable to 360 degree attack.
Britt - I am not sure that it was necessary to go to the extra work of putting the legs on the saucers. I think it is a good idea of using saucers since bass seem to create nest fairly distant from one another. I think the saucers would work just as well placed right on the dirt bottom. If one thinks the saucer needs to be leveled & raised off the bottom to keep it slightly less mucky then why not just lay the saucer on a used "recycled" large car tire that has been leveled onto a "step" or flat spot cut into the pond bottom. Tire will hold saucer off bottom and weight of gravel will hold saucer in the cavity of the tire. If you want the saucer higher off the bottom stack two tires and then place the saucer on top filled with gravel.
