I use the larger granular type Sea90 (not the fine ground) when I spread. I have two spreaders, one is a pull behind that is exactly the same as the one for my tractor (pto driven) except it is a wheel drive spreader, and both of them work fine. The key is not to let it get wet, and you may have to open the spreader a little wider than you would with traditional fertilizer. I just put some out on my yard last week without any issues with my pull behind.
