Thanks for the info. I cleaned out the Ozone filter in mine, less than a week after I got it. The I/O board has about 35k pages on it, but I was told that there was a previous board used in it (NTX I believe), so I have no idea how many pages are on the engines itself. Any ideas if you can still find unused Ozone filters anywhere? I think I'll replace the upper fan soon - any ideas what the specs are?