dobish":em1vmzkx said:
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....so, after listening to Dr. Ron, and reading what Mr. Holmes-Farley has to say here (which reinforces the thought), I'm not going to bother worrying about strontium and molybdenum concentrations...
....the four that I test with a test kit are Calcium, Alkalinity, Magnesium (every once in a great while), and pH (I'm hoping to get a Ph meter soon - I hate the pH test kits) ...are there any others that are really important? (besides SG) A person can purchase Iodine (which is hotly debated) and other trace element "juices"....are any worth the bother?
[ May 05, 2002: Message edited by: dobish ]</p>
With regard to molybdenum concentration... there basically isn't any way a hobbyist could measure it without farming it out to an outside lab. The idea that molybdenum and strontium should be added in a fixed ratio is almost certainly intellectually indefensible.
As far as strontium is concerned, there are persistent anecdotal accounts of bursts of coral growth after strontium supplements are used. I'm not ready to rule out the possibility that it is a potentially useful addition to a reef aquarium. I do have big problems with the addition of strontium to a tank in a way that isn't coupled (either by formulation or calculation) to the calcium consumption of the system.
As far as what you need to measure, Randy gave a very good overview. The only comment that I have to make about his note is that I'd probably regroup things and offer time intervals for testing. I'll order the list in decreasing frequency of sampling.
Temperature -- continuous monitoring is (almost) mandatory.
Salinity (or proxy variable like conductivity) -- continuous monitoring is highly desirable.
pH -- continuous monitoring is desirable.
Alkalinity --- new tanks, weekly or more frequently.
Calcium --- new tanks, biweekly.
Phosphate -- new tanks, biweekly.
Nitrate --- new tanks, monthly.
There are probably only two controversial aspects to this list. First, I would never entirely stop monitoring nutrients, even if the tank looks good. I've seen too many examples where unfortunate situations could have been headed off at the pass if the user had not completely stopped monitoring basic accumulating nutrients.
The most controversial aspect to the list is the strong suggestion that salinity be continuously monitored. The underlying reason for that suggestion is my observation of a lot of systems with salinity issues lately. They have two main origins. Either the user has much more export or import of salt than they thought they did, or they are simply using an inaccurabe salinity determination method. If you buy a conductivity monitor, you will have a good method, and you will actually tend to look at the value.
I've gone so far as to place salinity above pH (a traditional "continuously monitored" parameter) because I've seen or heard of very, very few cases where organisms died because of pH irregularities in an otherwise functioning reef system. I have recently heard of quite a number of instances where organisms have died because the user lost track of the salinity of the tank, and it wandered off into a lethal zone, either low or high.
In terms of the other test methods that a user should have available, I suggest that people have a dry reagent test kit for ammonia and nitrite handy for emergency use. Once the tank has cycled, one usually doesn't find detectable (by hobby tests) quantities of either. But emergencies will tend to happen at 2 AM, and the local pet store will almost invariably be closed or sold out of what you need.
In my experience, magnesium is almost completely conserved in reef systems. Low magnesium is almost always symptomatic of a poorly formulated salt, or more frequently, low overall salinity. Any slow magnesium depletion is easily corrected with partial water exchanges.
Craig
