You know, once you get the taste of saltwater, there is no other water.
The first thing you should try to decide on is what are you plans?
Seahorses are cool, but need lots of work and pretty much nothing else in there to bother them. Others here kept horses and can chime on in them.
If your thinking coral of any type, the issue at hand is well water. You really need RO/DI water, so can you hook up an RO unit? Depending on the well water pressure, you may also need a booster pump for the RO unit.
Water changes are similar to fw. 10% weekly or 20% biweekly is fine. You should mix your newly mixed saltwater 12-24 hrs before adding it to the tank. That's the only "aging" any water added into the tank will need. Top off are done with RO/DI water.
Once you get a better idea of the direction you want to head, we can help lead you to the dark side.....errrrr saltie side.
