There's no timetable for Tulowitzki's return, but it seems he'll be out at least a few more games with lower back spasms. From the Denver Post:

[Tulowitzki] said this injury is different than the stiff back that bothered him during spring training.

"That one kind of built up, but this time I actually did it swinging," he said. "I tweaked something, but hopefully with some treatment I will be back out there soon."

Rockies manager Jim Tracy said he won't rush his prized shortstop.

"Until we can get him loose and back up, we cannot afford to push the envelope on that," Tracy said. "Not with the situation he's dealing with."

Over at Purple Row, SBN's Rockies blog, they're spinning his time off into a positive:

Obviously this is a blow to the Rockies, but like some have advocated, giving Tulo and [Ian] Stewart, [who also missed Tuesday's game with back problems], some rest as the Rockies gear up for Rocktober can really pay long-term dividends for the club. Plus, if Eric Young, Jr. keeps hitting this well, the Rockies will have yet another weapon primed and ready for the postseason should they need him.