Ugh, I just wrote a ridiculously long reply and then it got deleted because I tried to PM you.
Okay, take two:
I would recommend running a validation. This is a one time test. You clean as you normally would (with a functioning ozone). Then you test for HPC, Y&M, Total Coliform, and pathogens. For water I'd say at a minimum you need E. Coli, Pseudomonas, and Listeria. Then if the pathogens are negative and you're satisfied with the indicator levels, that's your proof that your cleaning process is sufficient.
For daily testing, that's your verification. We did similar plus yeast & mold. Mold would give us a lot of problems when the water sources had algae blooms, particularly in the summer, and would give us an off musty taste. We always had issues with the filler heads, but maybe it was factory design. The historical data you have now can be used to set a baseline, and you can base "data driven" cleaning off how far off of the baseline your results are.
We had both Ozone and UV as kill steps, but we cleaned with a 7 step CIP weekly and a 5 step if we had to during the week. This consumed a LOT of water, and you have to monitor the 5T's very closely. If you're able to stick with ozone to clean as well I'd do that.