Don't use hot water with your RODI system

[Steve]

I recently got an RODI system from BRS and it came with tds meter. During my first few water changes I always checked the meter just to make sure it read 0 and I always used cold water only, however, during my last water change I decided to mix cold water with hot water so that the temp would be around the same as my tank. Just when my last 5 gallon bucket was full I happend to glance at the TDS meter and to my surprise it was reading 0.8ppm, so I decided to use a TDS meter that I got from ebay and it also gave me the same reading. I tested the first bucket and also gave me the same reading. I couldn't figure out what was wrong since the RODI system was only a couple of months old and i had only put through it at the most maybe 200gallons.
I decided to fill a glass cup with new RodI, but this time I only used cold water and the TDS read 0ppm.
I have no idea why using hot water would give you a different reading, but I don't want to imagine what could have happened if that water would have gone in my tank.

Steve

 

[kschweer]

The hot water makes the membrane expand allowing more to flow through it. The cold water makes the membrane contract making it catch more. The colder the better. Just keep an eye on things the hot water can ruin a membrane.