A little from column A, a little from column B. The threaded feet were originally a back up plan for the casters. While they could take all the weight, my intention is once the stand is in place to lower the feet to the point of just barely taking the weight of the casters. With it being on carpet obviously once there is more weight added it will sink a bit but in general the casters and the feet will both be taking the weight, with a bit more emphasis on the feet. I did some math today and figured that at 125 gallons you're looking at 1400 lbs. 200 lbs for the stand (and that is probably generous) + 100 lbs of gravel + 100 lbs just for incidentals and you're looking at 1800lbs. With 8 casters and 6 legs/feet each support is only taking 1800/14 = ~130 lbs ea so all should be good.
lol, I guess this is what happens when I don't pay attention to the login on the computer when I sit down. I didn't realize it posted under her account , not mine. sorry for the confusion