One of the least expensive and most valuable things the saltwater aquarist can do for the health of his or her system (or systems) is to keep a tank log. A tank log is simply a record of your tank parameters, observations and any significant changes. The reason a tank log is so valuable is, as I have blogged about before, stability is absolutely critical to success in this hobby. While it’s important for some species to have absolutely flawless water quality, overall, stability is more important to more species over the lifetime of your aquarium.
What Parameters Should Be Recorded?
During the cycling phase of a new saltwater aquarium, you will want to monitor ammonia, nitrites and nitrates, but once the tank is up and running, there are other parameters to record that will give you a good baseline on the stability of the system.
In my opinion, pH is one of the best parameters to record regularly, because a change in pH is often indicative of something else going on. If you record pH regularly (I record it hourly with a pH probe, but once a day or even every few days may suffice), you will be able to see trends over time that will give you invaluable insight into the stability (or lack thereof) of your system. When you see a change in trends, identify the cause of the change and correct it. Any sudden changes (with the exception of the expected daily pH spike associated with the diurnal light cycle) should be cause for a full battery of tests.
In addition to pH, temperature is an essential parameter to monitor regularly (again, I log it hourly using a temperature probe). Many species are tolerant of temperature fluctuations, but any daily temperature fluctuation of more than a couple degrees is stressful and can be the catalyst for disease or infestation. Also, several other parameters have a close relationship with temperature, so, for example, knowing at what temperature you recorded your specific gravity at 1.025 will be important when considering recorded changes to specific gravity over time.
Specific gravity is another parameter I like to monitor regularly because, even if you don’t use a conductivity probe, it’s so quick to check as part of your daily maintenance using a refractometer. Obviously, specific gravity (a.k.a. “saltiness”) is affected by evaporation, top-off and water changes, so monitoring your specific gravity over time will give you some insight into the effectiveness of your husbandry insofar as it is related to water changes. Some species (especially many inverts) are very sensitive to specific gravity, and fluctuations will cause stress and even death.
Reef aquarists will want to test for a variety of other parameters, but I will leave that to a later blog entry. The above parameters—pH, temperature and specific gravity—are the parameters for which I test and log hourly using electronic probes. If you are not going to use probes, then plan to test these parameters once a day AT THE SAME TIME EACH DAY. By reviewing trends over time, you will be able to keep an eye on how stable your aquarium really is. If one or more of these parameters begins to change over time, then your job will be two-fold:
1. Find the cause of the change
2. Correct if necessary
Observation versus Testing
Personally, I don’t test daily for nitrates or phosphates because I feel as if daily observation effectively clues me in to changes in either of these parameters. For example, If I begin to get an algae bloom, I have a pretty good hunch that my phosphates are becoming elevated, which I then confirm with a test kit. While there is no harm to testing for these parameters daily, I prefer to spend the time observing my fishes and leave the phosphate testing to once a month.
Observation, in many ways, is more important, in my opinion, than dogmatic testing. You should observe your tank and animals with a critical eye at least once a day and record notes about what you see. There truly is no better way to become a better aquarist than to observe your system and log your observations. Going back over your log weekly or monthly will reveal trends and subtle changes that may otherwise have gone unnoticed. These changes then become the basis for your personal research online, at your local marine aquarium society or in hobby literature, and you then become a better aquarist.
In conclusion, aim for stability by keeping a tank log. Strive to understand the cause and effect relationships surrounding any changes in your system, and you will, over time, become a more knowledgeable and experienced aquarist.
Adrian, Thanks for the comment! It really depends on the quality of the liverock (generally speaking, the lighter the better), but between 1 and 2 pounds of live rock per gallon of tank water is a good starting point. In terms of specific gravity, I keep mine high as well (very close to natural seawater). Part of the reason I do this is that I keep reef inverts in many of my tanks that are very sensitive to SG. Some aquarists with fish-only systems keep their SG lower because it may assist with parasite control. Hope that helps, and thanks for reading the blog!
Posted by: Ret | June 19, 2009 at 10:13 AM
i have a 36 gallon fish only marine tank.i would like to know how much live rock i would need.i have never used this before and all the advice you can give would be appreciated.also a shop owner has advised me to keep my sg at 1.026.this seems a lot,but he reckons he keeps all his tanks at this level.your comments on this would also be appreciated.thank you.
Posted by: adrian durran | June 08, 2009 at 04:20 AM
Erik- A great comment! Thanks. You are certainly right. I once wrote a piece saying that if I could only regularly test for one parameter, it would be pH BECAUSE IT IS SUCH A GOOD INDICATOR OF WHAT IS GOING ON THE TANK OVERALL. As you know, stability is key for many marine animals, and if the system tests unstable, you must find and address the root problem. Too many people get sucked down the road of throwing products at problems...
Posted by: Ret Talbot | March 13, 2009 at 11:09 AM
great blog Ret, about the only thing I would comment on is that PH shouldnt be considered an actual parameter but instead an indication of other parameters, if your PH is stable, and constant its a good indication that your parameters that can contribute to ph fluctuations are generally in the proper range, while great fluctuations beyond the norm are indicitave of some trouble in theb system somewhere, I think there should have been a little more emphasis on the fact that its the conditions in the tank that need to be adressed rather than simply buffering PH, while you did say to runa battery of tests if your ph is out of whack, there was little to no emphasis on the harm in just trying to buffer PH.
Again, Ret that was a good read. have a nice day.
Posted by: Erick Chambers | March 09, 2009 at 07:50 AM