First Timers - Tank Testing

In our previous installment of the First Timers Series, we talked about cycling your new aquarium and the nutrient testing that goes along with it. However, there are more tests that have to be done while you set up and maintain your aquarium and today's installment we will get into testing the physical parameters of your aquarium water. These tests include: salinity, temperature, pH as the big three with alkalinity and calcium being secondary for most aquarists at this stage, a topic we come back to. When monitoring your water's physical parameters, fairly simple equipment is fine for this stage in your marine aquarium timeline.

“Salinity” basically means “how salty is your aquarium water”? While there are degrees of saltiness in oceans around the world, especially as it relates to river deltas and estuaries, most of the fish and invertebrates we keep in marine aquariums are happiest being kept in water that as a specific gravity (how me measure salinity/saltiness) of 1.021 to 1.027. Displays that have invertebrates will need a tighter range at the high end of this, 1.025-1.027. If you open a bucket of quality aquarium salt like Tropic Marin and mix it according to the instructions, your specific gravity will always fall into this range. It is imperative that you measure the specific gravity regardless. If you make a mistake and mix too few or too many scoops of salt, your dedication to measurement will prevent a tragedy. Every time you do a water change, you'll need to do this measurement. You'll also need to measure your salinity daily as your aquarium will evaporate and as it does, the salt to water ratio is going to change. Basically, the salinity will rise as the water disappears. The only way to know how much impact this is having is to measure it.

Luckily for everyone, measuring salinity is easy and basically instant. The tool you'll need is called a hydrometer; they are inexpensive and easy to use. There is another tool you can use called a refractometer. They are much more expensive, more easy to misuse and really don't offer any advantage to beginning aquarists. Our recommendation for you is to buy a hydrometer, and follow the instructions on it. There are really only a few ways that hydrometers can give you a false reading. So ensure sure your salt is completely dissolved, fill it to the exact fill line, make sure your water temperature is around 75 to 80 Fahrenheit, make sure it is completely level when doing your readings, and always rinse it well with freshwater when you're done to remove all the salt that could bind it up. Take these simple steps, and your new tool will give you years of accurate service.

Next up is temperature. Unrecognized temperature problems are the single biggest aquarium failure cause of all time, and it's not close. As a result, our aquarium should have at least one thermometer. No, you should not just trust your heater to “just maintain a specific temperature,” as heaters can fail. Keeping a thermometer on or in the tank is inexpensive and not obtrusive. Occasionally check your in-aquarium thermometer against another one. Everything you are likely to keep in this aquariums is accustomed to an environment that is pretty stable and tropical in nature. Do your best to maintain a temperature between 75 and 78 degrees and never go over 82.

The last of the big three physical parameters is pH; pH is important mostly because it is an indicator of other problems. Correctly mixed saltwater will have a pH ranging from somewhere between 7.8 and 8.4. Mixed with water filtered by reverse osmosis (another article) your Tropic Marin salt mix should come out to a pH of 8.2 or so. If your freshly mixed saltwater pH is less than 7.8 it is a sign that the water you are using is overly acidic and you will need to utilize a different water source for mixing. The opposite is also true. Because of the nature of synthetic salt mixes, and their huge amount of buffering capacity (the tendency to be stable in pH), these issues rarely happen.

Your aquarium pH will fluctuate some between night and day schedules, and this is normal. In the light, micro and macro algae will use carbon dioxide and make oxygen, driving pH up. At night, carbon dioxide is released, driving pH down again. If this fluctuation is out side of our normal range of 7.8-8.4 it is a sign that the buffers in your salt have been depleted and your water change schedule needs to be more frequent, or larger changes. If these pH swings are dropping too low (which is usually the problem) you can generally help stabilize this by driving off excess CO2; this is done by adding oxygen to the aquarium via more surface agitation or with airstones. As a side note, we suggest only using airstones in a sump. Reading pH is very easy and can be done with test strips available from your Local Fish Store. These are cheap, readily available and plenty accurate enough for any beginning aquarist, and most advanced aquarists as well. Having good, consistent lighting where you read the results is likely the most important part of reading these tests accurately.

The other two most commonly tested physical aquarium parameters are alkalinity and calcium. Both of these parameters can be tested using fairly simple, fairly inexpensive test kits. However, if you are mixing quality salt to a known salinity and doing regular water changes, and you don't have problems with pH, then these two tests aren't going to tell you much. Both of these parameters can be affected by growing coral, clams, other invertebrates and algae. However, unless the density of these critters is very high in your display, they are not likely to make an impact on calcium or alkalinity as long as you keep up with water changes. A few years down the road, when you have good coraline coverage in your tank and a dense population of large corals and clams, you'll need to revisit this advice. But for now, head over to your LFS, tell them Quality Marine sent you, and pick up some simple testing supplies and a bucket of good salt. Happy Reefing!