How to Add Tannin Filtration to Viqua VT1 DWS Ultraviolet System
You are adding a third pre filter housing before the water flows through the ultraviolet light to remove the tannins. The outlet fitting from the second pre filter will need to be removed and added to the outlet of the third filter housing and the 3/8” tubing will need to be replaced. Flush system before drinking water. Note: this system is sized for one faucet only, this is not a whole house system.

Check out the conversion kit here https://thewaterestore.com/products/viqua-vt1-dws-tannin-conversion-kit