Keeping a SW tank is definetely more expensive than FW. There are several added costs that many people don't expect when deciding to get involved in the hobby.
The biggest shock is usually the cost per pound of live rock, in association with the amount needed for any given size tank.
Which brings me to tank size... tank size for SW is an important desicion. For many reasons really. It is important to inform new SW aquarists that although smaller tanks such as 30G or less, are do-able, having a larger tank will be easier to maintain water quality which ultimately determines the longterm success of the tank.
Now, I'm not saying that a 30G or less tank, can't or won't have longterm success, I am just mentioning that smaller systems require a more watchful eye, and dedicated husbandry practices.
You probably are aware, but I'll say it in the event you may not be.... larger volumes of water are less affected by slight changes to specific parameters...... therefore increasing overall system volume, offers more degrees of forgiveness, which comes in handy because SW inhabitants don't adapt well to changes in water quality.
It's always a good move for beginner SW aquarists to start with the biggest tank they can "outfit."
Many will say "biggest tank you can afford," but increasing tank size does increase the cost of the rest of the essential gear. (bigger skimmer, more LR, more lighting etc...)
I would recommend something aroung 55G to be a good starter size. You also need to figure out what type of tank you want to keep. If you have specific fish in mind, 30G's came be very limiting. You can't stock a SW tank like you can a FW tank. The general rule of thumb for stocking SW would give you about 6" of adult fish for a 30G tank. To break that down gives you a couple of clownfish and one other fish no bigger than a clown. Some might find that not to be enough space to do a setup like they envisioned.
As far as cost goes, it's really tough to put a number on it. For example, many companies offer protein skimmers. Some company's products are FAR better than others, and their prices reflect it. I will warn you that what ever you "figure" it will cost, you will be wrong, it will cost more. This isn't a bad thing if you have the money to do it, you'll enjoy most of your purchases. SW tends to consume a little more than fresh water, and the systems can get pretty elaborate when you run a full-blown reef. Reefs are REALLY cool, but they cost a good chunk of change.
In no way am I trying to deter you, I just like to give the heads up. I think that if you have the interest, go for it.
Now with whatever size tank you go with these are the supplies I think you'll need. (you may already have some of these items from your FW tanks)
-powerheads x 3 (2 for main tank circulation, 1 for SW mixing)
-powerstrips (hardware store)
-gfci (recommended for your safety)
-gounding probe (recommended for the safety of your tanks inhabitants)
-lights (and timers)
-tank and stand
-overflow (only if you go with a sump and don't have a drilled tank)
-rubbermaid containers for mixing salt water x 2 (1 for old water, 1 for new water)
-refractometer or hydrometer (refractometer is much more accurate)
-sand
-LR (1.5lbs per gallon)
-misc./cleaning supplies: - algae magnet (great for daily glass maintenance)
- algae scraper with handle (good for back of the tank)
-heaters x 3 (2 in main system incase one breaks unexpectedly, and 1 for heating new SW)
-thermometers x 2 (one for main tank and cheap one for SW mixing)
-tests kits (NH3, NO2, NO3, pH needed and Calcium and Alkalinity eventually for reef tank)
-skimmer w/ pump
-salt
-RO/DI
You will undoubtedly come across the topic of sumps and refugiums, if you aren't already familiar with them. They aren't necessary for SW tanks, but they are huge assets. Implementing a sump/fuge in your system has many benefits, but will also add cost.
I recommend reading the "sticky" at the top of this forum about getting started. It will give you a great overall summary of what's involved in keeping and setting up a SW tank.
Hope this helped.
Ryan
