Ughhh! Never speak of that again. Lol
But if you must use that horrid stuff; yes flush the hell out them before harvest. That will eliminate the chemical flavour. To flush there are products out there which are nice if you are short on the H2O stuff, but otherwise save some dough and just use water. For in ground you want to get on the verge of drowning the plants, wait a few days and repeat. For pot in regular soil you want to use three times the ratio of pot size for water. Ie, a 3 gallon container would receive 9 gallons of water and if you're into coir twice or even just equal will suffice

Don't get wrong I'm no organic nazi but I use mainly organic. Not trying to push the stuff, but the general organics line from general hydroponics is a very nice program... Though it can be time consuming making a mix. Not outlandishly expensive. Of course I mix other goodies in it too, mainly superthrive which is naturally occuring hormones and vitamin B and another product from gh koolbloom for the ripening stage

Another thing I'm just starting to experiment with from xtreme gardening are these organic feeder paks. Which are teabags you can put at the root zone and just water, or you can break open and pour into water as you would with salts. I'm also betting one could with an aerator brew compost tea for a day with these. I get these from my local 'dro shop in a pack of six for two dollar.

And as long as I'm plugging products growers extreme has got some nifty stuff. Mycoblast and soilblast in particular. Worth every cent.