you can switch, but it will take a week or two before youll want to get in it so be prepared.  Let your baquicil level drop as much as possible, get your ph situated into the "good" range (7.2 - 7.6), then double shock and filter, filter, filter! Make sure you clean your filter frequently, clean and soak if you have a cartridge, chemically clean and backwash if you have sand (you may want to replace the sand but it should't be necessary), and clean and replace media if you have DE. Keeping your ph level "good" will help the change go better, so check it and make any adjustments BEFORE you shock. You will have to do this two, three, or more times before the water will clear up.  When you do see the water start to clean up you will want to make sure you get a good algaecide in there too, putting it in before your water clears up will be a waste as you will be loosing water with the filter cleanings.