I have not tried ozone, but I did do some reading on the subject. Basically, there are two types of ozone systems. One adds only a small amount of ozone, probably won't have a noticeable effect unless your water quality is fairly good to begin with, and can be left on 24/7. All of the affordable options are in this category.
The other type is hideously expensive, much more powerful, and has the potential to kill your fish. These systems have a built in ORP meter, and turn on and off automatically. If something goes wrong with this control system, the ozone may become concentrated enough to bleach the gills of your fish. Even if the meter is working, you'll probably want a waterfall or something similar to help gas off any remaining ozone before the water returns to the pond. These more powerful ozone generators are the ones claimed to keep the water sterile. Whether or not that is a good thing is debatable.
Hi Otter It's a Hailea (chinese cheapy one) No ORP built in. Likewise from what i have read about them they can be dangerous to fish if to much Ozone is generated + it can smell bad if to high a setting (something like rotten eggs).
Hopefully have something set up by next weekend if all goes well.
100mg/hr into 1500l is .067mg/l hr, or about 1/15th what the rule of thumb calls for. Of course, that rule assumes that you'll reach your ORP target of about 350mv, and the controller will then switch off the O3. As I said before, I'm no expert on these systems. But from what I've read, I think it's unlikely you'll reach dangerous levels with the Hailea. However, an ORP meter will let you see if the ozone is making any difference, and it's a is a great tool for understanding your water quality anyway.
Hi again Trying to upload some piccies but struggling. If and when they appear 2 pics of the Ozone device built around a piece of sewage waste pipe with 1.5" pipe fittings, bottom has a rubber bung to seal and top is left open to atmosphere.
pic of the cabinet where everything lives pic of the homebrew upside down filter Pic of the Nitrite test, i recommend this liquid or tablet test over strips anyday which kinda brings me on to Freds comment. Now and again and i'm not sure why i get these nitrite spikes, the pic shows 2 tests the left 1 being a week ago, the right one taken today (colour in the pic is a bit deceiving) but the left one is about .25 (which is lower than what it was a few days earlier), todays test is practically zero. So i have been looking for another means of controling these nitrite peaks which is where the ozone thing came in.
Still waiting for an ORP device to turn up so i won't install the setup until then so i can get an idea of how well it is working (or not)