Repotting in flower IS good- I do it during week 3, when stretch is over, and I go through and look at my plants and see who looks like she's going to finish too big for her pot.
I don't know anything about the bark component of potting soils- if there's bark, it should be well composted and pretty well ground up. Are you sure that's not a bagged mix being packaged as 'top soil'?
Honestly if you suspect your soil sucks, instead of trying to make it not suck (which more than likely won't work or be more trouble than it's worth), why don't you run out and grab a bag of pro-mix potting soil or even just regular potting soil (no extra nutes though!). That will get you through to harvest anyway and you can go back to mixing your own from better ingredients next round if you like DIY media, or go shopping for a new type of bagged mix.
stinkyattic Reviewed by stinkyattic on . ph problem again...but found culprit?? o.k. third time to post same problem...PH..I am beginning to hate ph..lol..It keeps ending up high..near 8. Except now after reading page after page after page after page in the forums, I think I know what is causing it. My organic potting soil has a lot of bark in it, which after all that reading, I know is not good. Now they have been in flower for a week and only once did I have to move the lights and that was very little. That is what made me check the ph again cause no growth =no good. So Rating: 5