Uv sterilizer recommendation

[Monsaas]

I am looking to get a bigger uv sterilizer for my 210g display. I only have a 18w now and want to find something good for fighting parasites. What would be a recommended size in watts? I know flow is also a factor in this but I seen to not be able to get a answer to watts for my 210g. Any help is appreciated.

 

[KrisReef]

You need to decide how many times you want to filter your tank per hour and then buy a UV that can treat that flow rate.