You won't get close to the quality aeration with a fountain as you will with bottom aeration. Bottom Aeration adds dissolved oxygen to the water much better that fountains and even more importantly bottom aeration stirs the water from bottom to top keeping you from getting a dead layer below the thermal zones. If you run a bottom aerator for the first time don't be surprized by the fould rotten egg smell that comes from teh bottom. Depending on how old the pond is and the amount of silt at the bottom you may need to gradually aerate from the bottom ( a couple of hours a day for starters and work up to all day) or you may overwhelm the pond with oxygen starved water wich could cause a fish kill.