Re: probably a dumb grout question
I get it on occasion as well. I suspect that the red (and other streaky colors ) are the base tints used to get the grout color. It is probably not being mixed well enough and/or remixed before use. It's been a while since I've grouted anything, though I recall that when you mix it you're supposed to let it sit for 15 or 20 minutes, mix again and use.This is probably so that all of the particles get fully saturated and dissolved, the remix prior to use should blend in the spots of color. You may not be using enough water when mixing the batch - just a guess.
I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!