Usually when people use foliar feeding, it doesn't go well. You shouldn't need to foliar at all, especially in DWC. Also, you might try not fighting the pH so much. In other words let it drift some, don't be so quick to get it down to 5.5. I'm not sure that 5.5 is optimal, some say it's the bottom of the range, but frankly the whole range could be 5.5 to 6.8. I'd ask about this is the hydro forum and do some research elsewhere and see what you find. Why did you switch nutes?