My comments on your project:
- The cost of running a 230W peltier cooler is going to be double or more than a normal 250W chiller
- The cold side of the peltier gets colder when the hot side gets cooler, but I don't think the hot side can be cool efficiently enough for the cold side to cool your tank. I the peltier may end up running nearly non-stop.
- Even peltier chillers made by Resun, Teco, etc. are not popular because they are not efficient
Just my opinion.