my first marine tank, ten years in the making

[domvonn]

Originally Posted by illumnae

Actually hor, in the long run RO/DI is more economical than just DI. Both of them will output the same water (DI water), so it's not a matter of what you're keeping.

The difference is that in RO/DI the RO membrane will first remove alot of the impurities, so when the water goes into the DI resin, there is less to remove. Compared to the pure DI, all the impurities will go straight to your DI resin which removes them. Both output pure TDS 0 DI water, but the DI system will require much much more frequent replacement of expensive DI resin, whereas the RO/DI system will have much less replacement of the DI resin. RO membrane can easily last 3-5 years before needing to be replaced.

However, if your only use of the DI system is for a small amount of water, then you won't feel the pinch as much la. I use my RO/DI system for my freshwater tanks (6x2.5x2.5 and 4x2x2) as well as my marine tanks (3x2x2 and 1x1x1) so it definitely makes a huge difference, since I use over 1000 litres of purified water a week.

agreed , i believe some pple may not want RO becos of the waste water ba.