Should I Install a UV Filter in My Pond? If you have a proper filtration system, adequate aeration, and healthy plant material, you shouldn’t need a UV filter. You should generally be able to keep your pond water clear without added equipment (ie UVs, Iongens, Dosing Systems, Chemicals). That said, some ponds thrive using UV filtration. Clearing Green Water A UV filter can help in clearing green water. Small single-celled algae will pass through the media in your biological filter. However, when this single-celled algae passes through a UV, these cells can become damaged allowing them to clump together forming a larger mass. This can then be filtered out in your bio filter. Required Flow Rate An issue with UV filters is that they require a specific flow rate (gph) to function properly. Most homeowners don’t realize this. You can’t install an inline UV onto your existing piping with a 3, 000+ gph pump; it won’t be effective. Most UV's have a maximum flow rate under 2, 000 gph. Therefore, to account for this, you have to throttle down your pump, manifold off the UV, or run the UV off a separate pump. The latter is suggested as it makes removing the UV the easiest for maintenance. Conclusion Some people might be naturalistic, but have a firm believe in biological filtration, excessive plants, and water changes. I’m not saying UVs don’t work, I think they are an extra cost, another thing to hide, and require more yearly maintenance. That said, some ponds need a UV.