| Both places are seemingly appropriate.
After everything is an easy place to retrofit. Mostly because most UVs are designed for pressurized situations.
In the skimmer is also fine, as long as you remember to leave it off when the pond is just starting and you don't want to kill any beneficial bacteria that might be floating through (you want the bacteria to seed your bio-chamber(s)).
The reason against skimmer/settlement chamber is that dirty water can reduce the effectiveness of the UV rays. But with strong enough UV it shouldn't be a problem. |