Ro/di question

[Tyler_Fishman]

do you really need de-ionization? The unit I would like to purchase has a separate di unit

 

[Crabs McJones]

Depended on your source water, you dont NEED de-ionization, but it is a nice little polish after the RO and prefilters to make sure that you are achieving 0 TDS water. Do you have a tds meter to measure what your RO out put is? I know on mine I generally get anywhere from 10-15 TDS out the membrane, and then 0 after the DI chamber.

 

[chipmunkofdoom2]

There are several benefits to having a DI stage in the context of purifying water for reefkeeping. The first is that reverse osmosis alone will not remove all the solids from the water. Even a relatively high rejection rate of 99%, which is only possible at ideal temperature and pressures, still leaves 1% of the solids in the water. As conditions get less ideal (the temperature, pressure, or both drop), the rejection rate gets worse, meaning more solids in the product water. The second reason to run DI is that the charged molecules that are not removed by the RO membrane tend to be things that are particularly problematic in reef tanks. Things like copper, ammonia (as ammonium), phosphate and silicate all get handled by the DI resin, not the RO membrane. Without a DI resin, all these things could be going into your tank.

You might be able to get by without a DI stage, but I personally wouldn't. We spend thousands of dollars on our reef tanks. It seems counter-intuitive to put all that at risk just to save a few bucks and not run DI resin.