The cacti are about 32" tall and doing ok; is it good or bad for them to train the garden hose so water flows into the center interior? It seems to take quite a bit without overflowing.
Watering Barrel Cacti
Certified GKH Gardening Expert
While that should be fine, keep in mind that these plants require very little watering. They are native to arid desert regions and usually have only rainfall to supply their moisture needs. Therefore, only water your barrel cactus once a week in summer to avoid root rot.