If you’re looking for any information on sumps, saltwater critter ID, or aquarium photography, Marc Levenson’s site www.melevsreef.com is a great resource. He also sells RO/DI units that are second to none. I bought one from him for my reef needs and I couldn’t be happier with it.

My RO/DI Unit from Melev's Reef set up above my washer/dryer

You can check it out here:

http://www.melevsreef.com/ro_di.html