tds meter question

[Delphinus]

I get a surge of TDS (post-RO/pre-DI) when I turn on my RO/DI that can be anywhere up to 150. It falls off quickly though, within 10 seconds usually it's down to zero. The post-DI is always zero - if not, the DI is spent and needs to be replaced.

I always kind of wondered if this TDS surging is normal (I have my RO/DI on only to fill my 50gal topup reservoir, about once every two weeks, otherwise it's off). It sort of looks like, judging by the comments so far, that this may not really be typical for others. Hmmm. Although maybe the way I use my RO/DI isn't typical..