Gray - White burbur,nylon. cat puke stains went away when i pre treat with power burst,carpet looked great.6 hours later the yellow spots were all over again.what causes this and will 30 vol work to remove these spots
"sounds like the spots are wicking up because you didn't actually remove them"
the pre-spray is emulsifying them and likely sliding down to the base/backing.
That's why they disappear from the top of the fiber
Happens with a lot of spots ..and in particular on berbers
drop a marker on the spot (I use pocket change) drop a coin on the spot after pre-sprayed .
That way you'll know that spot needs through flush/rinse extract (if it's gone where you get there with the wand )