Can you have too many snails?

i dont think you can i have 50 snails and 50 crabs in a 72 bow

 

You can have them, but you'd better have a consistently messy tank or you'll likely end up littered with empty shells. On the bright side, dying snails will feed algae, feeding the living snails!

I've got one turbo, ~20 astrea snails, 0 crabs, and hitchhiking asterina stars in my 120 and in ~18 months haven't lost more than 2 snails. It's weeks between glass scrapings. I'm actually in the habit of overfeeding the tank when clean in order to feed the snails. I think it's ridiculous that some folks are in the habit of an annual or bi-annual clean up crew replacement. Start closer to the balance point and you won't have to remedy a clean up crew crash.
Both of those packages, in my opinion, are overkill for a 90.

 

Well when I ran my 125 I had 500+ Ilyanassa snails in my tank I lost probably 30-40 in a year but thats it. And let me tell you what when I would feed the tank the sand would littlerely come alive with snails kinda cool. That is all I used absolutley no crabs they did a pretty good job but still had to clean the glass every couple of days but I think that is because I run my halides for 12 hours a day that could be why. Crabs always seem to mess up my frags and LPS become irritated when crabs walk on them.

 

I like both those packs. You can easily put that many in your tank. Scarlets will eat snails too. They'll just not actively hunt them down for dinner. I started out with a similar package to #2 and have around 50% of them after a year.  #2 could be a bit much.  If thet are for a new tank then it should be good.  I enjoy watching the activity of that many too.

 

I'd agree with ryan that both those are overkill. I'd get astreas instead of turbo snails and not get any crabs. If you had to get crabs, I'd get the scarlet, they seem to be the most harmless and easy going of the crabs.
I started with 8 astreas about 3 years ago. I think I went down to about 6, but now I'm up to 7 because I've got an astrea baby in there now. All my zebra crabs died but my two scarlets are still kicking.

 

those numbers sound good to me, i have approximately 70 turbos and a hundred blue legs in my tank, 125 gal.

i also had 15 astrea snails in my tank that at some point had young, i now have possibly 100 of them and they are growing fast.

i have never noticed any predation with my hermits but there are a couple empty turbo shells in my tank.

if you like peppermint shrimp, they have a good deal on them if you buy 5 or more, something like 3 bucks a paice, or that was the price last time i looked. i got that deal too.