Difference b/w Fresh and Saltwater?

There are difs between salt and fresh besides the salt aspect. You still hava to care for it as a freshwater aquarium (cycling, cleaning, testing) but there's a little more involved.

Saltwater fish are taken out of the ocean which is more stable than the environments of freshwater fish. So they are touchy when it comes to water quality. Regular tank maintenence is a must. Cannot skip this stuff.

You cannot have as many fish in a saltwater setup as you would in a freshwater setup.

The critical parameters of a saltwater tank are pH, nitrate, salinity, and temperature.

Some of the equipment is more expensive.

These are just a few difs. The links below have more and elaborate on them.

http://www.freshmarine.com/difference-freshwater-s...

http://www.pets.ca/articles/freshwater-saltwater-a...

http://www.epinions.com/content_1486725252

http://saltwater-aquarium-guide.net/saltwater-aqua...

If I were you, I'd have my own saltwater tank for a while, before taking money to care for those of others... Or at least research them HEAVILY.

It all depends on what kind of Saltwater setup u are looking to maintain. there is the Coral tank and there is just the saltwater fish tank.

Coral Tank:

U will need a lot of lighting. i had a setup with a metal halide light and i had 2 45g filters running it with a protein skimmer as the actual filter. the 2 45g filters were filled with live rock and only used to keep the water moving in the tank. the way i had it set up, with crushed coral and live rock, the only maintenance i had on it was to add fresh water twice a month and add salt once a month. very easy.

Fish Tank:

U will not need the same lighting on this tank. i would recommend using double the filters required for that size tank. used crush coral on the bottom and live rock. should always have a protein skimmer on any saltwater tank.

either can be set up and maintained with ease. both are expensive but both are totally worth the expense.

Salt

edit: Ok, for a better answer. I hear red algea is a big problem in saltwater tanks. Also for the water changes, you need to add the same percentage of salt that is already in the tank. So you will need some testing equipment. Some people just add water to counter act the evaporation. And some of those people don't realize, you can't add more salt if you just add water.

Some people use a protein skimmer.