Have to agree with bperc. Best bet would be dive park at Casino point. More options for getting there and back on the express, good transport of gear to the point, easy entry/exit, and good diving, plus walking distance to several places to eat, fill station and lockers next to the park, and if staying overnight several options from budget on up.
another option to consider is one of several charter boats heading to Catalina for a 3-tank dive.
July 22, 23 is a Monday Tuesday so I don't know of any boats going on those day except the Catalina express.
Not sure where you are coming from and your profile shows warm water diving. Our waters during July should be around 64ish, I use a 7mm with gloves/hood/booties.
Enjoy.