Let's go shopping!
Well, you have your tank, filters and lights selected, so are you ready to set up your tank? I wish it were that simple. There are still some products that must be bought and precautions that need to be taken.
As for products, we still need the essential elements and equipment to make it a happy and functioning tank. These include substrate, pH buffer, a test kit, a hydrometer, salt, heater and an aquarium grade sealant. Let's take those one at a time.
The debate over to use substrate or not has been discussed for quite a long time. The original consensus was to have no substrate at all. The thinking behind this was that substrate was a trap for waste and uneaten foods. By having no substrate, the tank bottom could easily be vacuumed of any detritus during water changes. However, there was always the desire to recreate the most natural looking environment. Not to mention, many animals require substrate to live happily. Some Wrasses and Rays bury themselves, Gobies sift through it in search of food and Jawfish use it to construct burrows, just to name a few. So, the experimentation of using substrate began to grow more rapidly and the benefits were discovered. Aquarist tried different types of sand and crushed coral or mixtures of the two. Then a new debate arose, how deep to make it? You probably will ask a few different people about what is right for you and you probably will probably get a few different answers, including some who still feel the "old school" way is best. Basically, it boils down to you and what you plan on keeping. There are a couple of choices for substrate in the marine aquarium. You can have "live" or "non-live" sand, and crushed coral. "Live" sand is simply sand that has been packed in seawater harboring tons of "beneficial" bacteria, microorganisms and tiny crustaceans. This sand is terrific for improving your overall ability to break down waste, cycling the tank and providing food for some burrowing animals. "Non-live" sand is basically dry sand containing no "life" initially, however it eventually will as the tank matures. Next would be crushed coral, which can be calcite, aragonite, dolomite or any combination of those. The benefit in using crushed coral in your marine aquarium comes from the fact that using a calcareous substance acts as a buffer for calcium levels in your system and helps to maintain the proper pH. In order to determine how much sand or crushed coral to buy, you can utilize the Substrate calculator located in the Resources section of FishDB.com. There you can calculate how much you will need for your size tank and the desired depth you are going for.
Another "must have" is a bottle of pH Buffer. Even if you don't know what it is yet, you will become very familiar with it. The typical pH range for the marine aquarium is 8.1 - 8.3. Mean nothing to you? No worries. This will be covered shortly. Just know that you need to get a large enough bottle for your size tank. Keep in mind you will use this even after your tank is functioning, so get enough to last.
The next item is so crucial. I cannot stress enough, the importance of a good test kit. You cannot begin or maintain an aquarium without one. You need to be able to test your pH, Ammonia, Nitrites and Nitrates. All these will be explained once your tank is up and running, but for now lets continue on.
Next you will need a Hydrometer. This is a simple measuring device with typically a floating needle, used to determine the specific gravity of a liquid. In our case, that liquid would be seawater. The specific gravity that we wish to maintain in our aquarium will be in the range of 1.020 - 1.024. Sound confusing? Well, defining specific gravity can be and will take much more room than this paragraph to fully understand. Very simply, it is the ratio of the density of ions in a particular liquid as compared to a constant at room temperature. Stop scratching your head. All you need to know right now is this little device will help you estimate the salinity of your water.
That brings us to the heater. Any "aquarium safe" glass heater will work fine for a saltwater aquarium. Just purchase one that is rated for your size tank. This is usually 3-6 watts per gallon for most systems. So, a 125-gallon tank with a 15-gallon sump would require a heater rated at 375 - 750 watts. However, it is usually sold as "up to" a certain gallon amount. Just remember to include the volume in your sump if you are using one. Now, there is no reason to really go out and buy the most expensive model. More than likely, once the tank is up and running you will no longer be using a heater if you have a powerful lighting system. That alone will keep your temperature up. But it is still a good idea to have one for other applications such as a quarantine tank or for preparing new water for water changes.
So, what is the next item to check off the list? Salt, this one is pretty obvious. Of course you need to buy salt for a saltwater aquarium, but which one? There are a few brands to choose from, and no, table salt won't work. As far as picking one, this is up to you. Ask around and look for some reviews. The best advice is to keep with the major brands, i.e. Instant Ocean, Oceanic, Kent etc. What are the differences? For the most part, the amounts of particular trace elements each brand contains and the cost.
Ok, we are almost ready to leave the store. Grab a tube of aquarium "safe" sealant, run down your checklist and hit the road. No, I'm sorry, there are no fish on that list. Patience.