ML, Not knowing what aeration system you have and considering they vary greatly in circulation rates Ill suggest the following just so you dont get caught in a bad situation as trout always concern me.Many of the posts on winter aeration are made with logistics in mind. So that needs to be factored in when making adjustments to your own needs.The need for winter aeration can and does differ from pond to pond even when located in the same general location. I know you have a different climate than we do here in Ohio. My son is stationed in Norfolk and I know he has a lot milder climate than we do and I believe you are somewhat north and west of there. Considering that and in your situation I might do one of a few simple things.Simply slow down the existing diffuser by venting a lot of the pump cfm to the air. If you ran at 5 psi take it to 1-2 psi for example, or add a second diffuser in an off set part of the pond in 4 ft of water and aerate with that instead or move the existing diffuser to the same shallow water. If adding a vent to the existing system is confusing let me know and Ill be glad to step you through it, simple plumbing can be bought locally for about $5-$7, If you want to add an off set diffuser let me know that also as I have "many" diffusers that we have removed over the years that did not perform as main diffusers and you can have one of them,(another benefit posting on PB) they work great as winter diffusers.Bruce is correct in his comments on less than 24/7 running, some diffusers can pull from the bottom too much "crud" just from the short time the system has been off.Your water seems very clean however and you can thank the water temps and chara for that. Some diffusers are designed with the above in mind and have specific bases built that put the diffusers x number of inches of the bottom to avoid this.Good Luck