A couple of thoughts dadonoflaw.
First an 18 watt UV on a 180 is totally inadequate, can't possibly do any good. It would be like peeing in the ocean expecting to lower the
salinity. A UV unit
MUST be adequately sized for the application taking into account the size of the aquarium and then
MUST have the proper sized pump for adequate flow. Size it wrong or put too little or too much flow through the UV and you are wasting your money. Sadly, most UV manufacturers
overrate their UV units. Like any other decision in this hobby you have to do your research. Asking a question on TR and expecting all the correct answers, while a good place to start is only just that,
a start, you have to research most things further.
Secondly, the two elements, UV and ozone do different things. I think you have some conception of what UV does since you bought one. Ozone does something entirely different and while ozone does kill pathogens that come in contact with it, that's not it's primary function in aquarium usage. Ozone is used to boost the effectiveness of your
skimmer and raise
ORP. However, indiscriminate use of ozone without a controller can be very bad in your home especially in closed or small rooms. Ozone is highly oxidative and will degrade plastics and rubber over time. In high concentrations ozone can be hazardous to your health although, that is unlikely using the small units meant for aquarium use. But you should know about the dangers before you apply ozone to a system.
We've had this conversation before, it seems. Here's a link to an article about UV and Ozone use in aquariums.
MarPhysFilt Please read it and search for other information on the two subjects. I simply typed "ozone for aquariums" in Google and came up with a treasure of links.
icon under there name and give them Reputation points
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