I think you need to enaure you dont mix ozone and uv uses, as they do different things for the aquarium in different ways
Here is a extract i used to setup my ozone ans also what it does for an aquarium
What can Ozone do for the Aquarium?
Due to its oxidizing capabilities, ozone can break down harmful waste products produced by fish. In a marine aquarium (or
in a freshwater tank with pH higher than 7.5), ammonia is efficiently oxidized to less harmful nitrite and further to nitrate. This oxidation reaction can also be performed by bacteria in a biological filter however it is advantageous to install an ozonizer as a backup to prevent dangerously high ammonia levels. This backup function is especially important in aquaria with a lot of fish and subsequently a lot of waste.
More complex organic wastes, such as the substances that
turn the water yellow, cannot be removed by biological or mechanical filtration. Ozone however, breaks up their structure, so that the fragments can be cleared up by the filter’s bacteria or through protein skimming. The use of Ozone leads to “Crystal
Clear” water.
Another important property of Ozone is its sterilizing ability. Harmful bacteria and other possible pathogens that float in the water are efficiently killed by ozone. In the sea the amount of floating bacteria is always very low, due to the antiseptic action of natural sea water. In the aquarium however, bacteria that can be harmful to many aquarium inhabitants, find a favorable environment for rapid reproduction. The term “sterilizing” should not be taken too literally. The amount of ozone administered should be just enough to kill only surplus bacteria. Totally sterile water is also harmful, to fish and invertebrates.
Ozone should never be introduced directly to the aquarium water: it must be administered through an isolated chamber like a pressurized ozone reactor or a protein skimmer. A freshwater aquarium can be ozonized by connecting the ozonizer to an air-driven internal filter.
1.3 How much Ozone should be used?
The ideal dosage will vary for each aquarium. The right dosage of ozone is dependent on a number of factors: the volume
of water, the water flow rate, the ozonized air flow rate, the amount of dissolved organic matter, the fish density, the type of biological filtration and additional equipment in use. As a guideline, the ozone production should be between 5 and 15 mg/hr per 25 gallon (100 liter) of aquarium water.
Aquaria densely populated with fish need more ozone input levels, values higher than 430 mV can be dangerous, values of 600 mV will cause increased levels of sterilization which should not even be considered for aquarium use.
Values below 200 mV indicate an accumulation of organic wastes and a low oxygen level. Negative redox potentials are also possible indicating anaerobic conditions which can occur, for example, under the bottom gravel.
