User Manual
De-Ionization Add-On Kit – 10”x2.5” 
This de-ionization filter is designed to serve as a post, polishing stage for any 
Reverse Osmosis system. After an RO system, the product water may contain trace 
amounts of nitrates, phosphates, and silicates as well other total dissolved solids 
(TDS). Certain applications such as aquarium, medical, manufacturing and others 
require 99.99% ultra pure, 0 PPM water. This DI filter will remove any leftover 
contaminants giving you the purest H2O available. 
Included in Box 
-  (1) 10”x2.5” – DI cartridge with mixed bed, color changing DI resin (anion resins to filter 
negatively charged ions and cation resins to filter positively charged ions) 
-  (1) 10” filter housing with clear canister and white cap 
-  (2) 1/4” Quick Connect fittings for in/out 
-  (1) White powder coated metal wall mounting bracket 
-  (4) Stainless steel screws for bracket 
-  (1) 2 foot piece of white 1/4” tubing 
Instructions 
Begin by mounting bracket to the filter housing using the 4 included screws. Mount bracket to 
wall or other location using appropriate fasteners (not included). Use included length of tubing 
to hook filter up to the outlet of your Reverse Osmosis system. The RO product water will go 
through the DI filter and come out with 0 PPM of contaminants. The DI resin inside the 
cartridge upon initial installation appears green. Once the resin has exhausted its useful life and 
is no longer capable of removing TDS it will turn a prominent blue color. When this begin to 
happen it’s time to either replace the entire cartridge or to replace the DI resin inside the 
cartridge. Adding another DI stage after this one will ensure the purest water at all times.  
Specs: 0.25 Gallon Per Minute maximum flow rate. Estimate life is 7,500 Parts Per Million 
Example: Estimated number of gallons cartridge is good for at 5 PPM feed water is 1,500 
gallons. Divide estimated life by feed water PPM to get estimated number of gallons. 
If you have any questions please email: support@hydrologicsystems.com 
or call us at 888-426-5644 

