taking care of a BIG tank

[SnozULoz]

I have an oppurtunity to make some extra cash by taking care of a 1500 gallon
saltwater fish only tank at a restaurant.  I have had a reef tank and a
saltwater fish tank for over 10 years, however only 75 gallons....
I am wondering if any one has had experience with a large tank like this....
Am I getting in over my head?  
They want a bi monthly check and cleaning.  
I remember when I had a fish only tank that you could keep a low level of
copper in the tank and it would somewhat prevent disease and algae growth.  
Would that work in a huge tank like this?
Thanks for any advice or experiences..
Steve