Congrats on completing you pool work :cool2:
There are more diving professionals (DM and up), shop owners, dive medicine experts, industry leaders, and manufacturers here on ScubaBoard than you will ever be able to meet anywhere else. If you take the time to look around, and read, you'll be able to spot the true professionals, and weed out the "know-it-alls". Although, there are some that are Professional Know-It-Alls and those people you can trust.
There are hand signals to tell the other diver no, other than the single finger. You could hold a hand up like a traffic cop, or a clenched fist, or just shake your head no. One thing to remember is that, if you separate from your buddy, BOTH of you are now diving solo. Discussing the dive plan with your instabuddy BEFORE the dive would ensure that both of you understand each others personal limitations.
That's funny!