For a 5 month old scope, I was surprised to find dust and dirt inside the tube, on the back of the corrector and on the mirror. The front side was pretty dirty just because I live in the desert. Surprisingly, the primary mirror had a finger smudge and some other sort of residue on an area about 1" square. So I decided to pull the corrector off my C9.25 today and gave it and the primary mirror a bath.
I know, I know, I didn't HAVE to clean it. But as a new scope I decided now was the time and then I'll leave it for a few years.
I used the mix from ASO http://arksky.org/as...cleaning-system as my baseline but did not include the windex and increased the amount of 99% isopropyl. Probably about a 25% solution. Nor did I filter the distilled water; it's laboratory reagent grade, for crying out loud. I didn't buy it at Safeway.
The initial cleaning left some streaks which would not come off using the ASO rinse formula. That just left more streaks. I decided that the PhotoFlo must be the culprit, so I used cotton to lightly swab pure distilled water followed by a very light buffing with the cotton afterwards to remove any remaining haze or discoloration. Very nice.
IMHO, PhotoFlo might be good if you have a large optic and are really using a lot of fluid for rinse. But for just a dab and clean, it seems to me to do more harm than good. So now I have a big bottle of PhotoFlo to sell; with only 2 drops used!
One other thought. Once I pulled the corrector retaining ring, I was surprised to find that the little nylon allen screws around the perimeter aren't long enough to "retain" it. They seem to be more for protecting the edge of the corrector by ensuring that it never comes into contact with the housing. BE SURE to have your scope tilted sightly skywards because those little screws will not retain the corrector and it could fall forward.