I will be visiting in July and I was wondering which Dive shops in Port Douglas are recommended for trips to the Reef.

 

All are very good up there and the industry is highly regulated, any dive shop that has been established for a while would be ok!
I would play it by ear and have a look once you get there.
Check out some of these sites

http://www.divethereef.com/DiveSelec...FREcagodx1KhRg

http://www.portdouglasinfo.com/?gcli...FQwcawod4jelRg

http://www.underwater.com.au/dive_shops.php

I hope you enjoy your holiday - it is a very special place!