I just bought a house and the septic system needs a new aerator. The septic tank has three chambers. The middle chamber used to have an in-tank aerator that sat in the tank riser with the long shaft going down into the chamber to stir the contents and supply air. This aerator was removed from the tank when the previous owner passed away because the house was going to sit vacant for a while. The cleaning crew mistakenly threw the aerator away while cleaning up. I'd like to know if I need to go with this style aerator (which has many disadvantages from what I've read) or if I can go with the style that just puts an air diffuser in the tank to supply the oxygen needed with the pump located outside the tank. The disadvantages seem to be higher monthly electricity costs (estimated $20 per month more), more potential for problems due to being located in the tank, possibly less I could repair if something did go wrong (the external pumps have rebuild kits you can buy). Just need some opinions on this. I like the fact that the external pump runs on less amps and will save money each month ontop of being more easily repaired. But I don't know if it will work correctly for the setup this house has and no local sewer folks have been able to answer this question yet. Thanks!