Ozone is very reactive and needs to be used carefully for both you, and your fishes safety. I have no idea what the oxidative effect of the O3 would have on ferts or plants but I wouldn't bother really. I can't see the need for a UV either unless you have a problem with green algae or perhaps using a UV steriliser to combat certain parasites.
Hi Ed, thanks for your reply. I was more thinking of trying either as a preventive measure against bacteria, algae etc. The reason I am asking is for one, to see what everyone else thinks and two I got both an ozone processor and a UV when I bought the tank and just haven't bothered to connect either.....
UV maybe, but not O3.
I've used O3 in marine systems, I suppose it could be used some in FW....but there's not much real need, or usage.
UV better suits the issues of killing things in the water as it passes through.