Pond Boss Forums AERATION Systems questions Novice needs advise and comments

I thought I was doing things right until I joined this post and started reading. Now I think I am totally screwing up! My pond is small, about 1/8 acre with an average depth of 4' supplied by run off. I knew when I built that this little hole could become septic real quick and have winter kill unless I aerate. I searched the net and everywhere else for a aeration system but could not bring myself to spend the kind of $ they are, more than I spent to put the pond in. My little brain said I could build one out of a pump, some hose, and a home built venturi which sucks in ambient air and injects it into the water stream. The same way a carburetor works on your standard combustion engine. Here are the spec's on the system:

1/3hp 50 gpm @5'head cont. duty pump, 1 1/2 ID hose connected to a "T" style aerator made from 1 1/2" pvc pipe, the jet stream is reduced to 3/4" at the venturi which creates the vacuum to draw in the air. Pumps alot of water and injects alot of air. Total system cost was $160.00.

I run the pump maybe 24-48hrs on and 24-48hrs off, I do not know any better. At 3000 gals a hour I am probably turning this entire body of water over every every 24-48hrs.

My question is this...am I over doing it and what about temp. fish stress in the winter?? Is this system even really doing anything for my DO?

Dumb novice needs advise.

Anyone have comments and advise on this ?