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danmhippo

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I have always been perplexed about strontium and molybdium concentration in my tank. I have test kits to test for strontium by Salifert, but the test always ends up "out of range", or zero to be more precise. I have also heard of importance of strontium. I have various softies, LPS, clams, and sponges in the tank, all are growing nicely for the last 2 years. I have not added strontium additives ever.

Is it my test kits or me? I have tested for Sr on newly mixed salt mix and have tested against my tank water, all comes out zero. Is strontium really that important in reef building? Which test kit do you recommend for them? Or should I not worry about testing for it as long as I make monthly water change, and make sure the corals are not showing signs of slowed growth? What are the symptom to look for Strontium and Molybdium deficiency?
 

dobish

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alright....
...a couple things here....

...first of all, it is my understanding that strontium has no real benefit to our aquaria...strontium is used during calcification, but it is actually a "poison" of sorts by slowing down the calcifications process. Strontium has the same properties of calcium because it is in the same family of elements since it resides directly below calcium in the periodic chart. However, it is my understanding that strontium is not required for calcification to occur, and when it is present it actually slows down the calcification process...therefore, it is my understanding, that low strontium levels won't really hurt anything in our reefs....

....secondly, I found this article by Dr. Ron to be very interesting about levels of trace elements in our tanks -- I apologize for posting a link to another on-line periodical, but I'm doing it because I think it might add to the discussion... http://reefkeeping.com/issues/2002-03/rs/feature/index.htm ...Figure 2 in the article compares the normal level of elements in the tested aquaria in the sample to NSW, and it shows that, on the average, strontium usually runs lower than the normal concentration in NSW....this might be the problem with your case danmhippo...

As for molybdenum, I'm not sure what role it plays in our reefs, but will be watching to see what the opinions are...

Please don't take this as argumentative, I'm posting this to help start a discussion. What I've written here is my
understandingof the interaction of elements in our reef, I by no means think I'm an "expert"...thanks...
 

dobish

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geez....Jim, I just noticed as I tested the link to that article that you submitted a water sample to Dr. Ron for use in that article....hmmmm.....so you should be aware of the article already....and I have to say 'thanks' for taking part in research that I believe is important to the hobby...

[ May 04, 2002: Message edited by: dobish ]</p>
 

danmhippo

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icon_smile.gif


Anyone else on the subject? I am not a chemist, but is eager to know the answer.

TIA, Jimmy
 

randy holmes-farley

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I personally do not spend any time worring about strontium or molybdenum.

There is a paucity of information indicating that strontium has significant benefits. Maybe it has none, maybe it has undemonstrated benefits. In any case, it depletes slowly, and is present in many salt mixes. I'd suggest that there are more important things to worry about.

Molybdenum, OTOH, has great biological uses. But, in Ron's study, it doesn't seem to be greatly depleted in any reef tanks, and it is present in excess (over NSW) in some. So I see no reason to worry about it either.
 

CraigBingman

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<blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr>Originally posted by danmhippo:
<strong>I have always been perplexed about strontium and molybdium concentration in my tank. I have test kits to test for strontium by Salifert, but the test always ends up "out of range", or zero to be more precise. I have also heard of importance of strontium. I have various softies, LPS, clams, and sponges in the tank, all are growing nicely for the last 2 years. I have not added strontium additives ever.

Is it my test kits or me? I have tested for Sr on newly mixed salt mix and have tested against my tank water, all comes out zero. Is strontium really that important in reef building? Which test kit do you recommend for them? Or should I not worry about testing for it as long as I make monthly water change, and make sure the corals are not showing signs of slowed growth? What are the symptom to look for Strontium and Molybdium deficiency?</strong><hr></blockquote>

There are a couple of issues here.

First, I noticed that you mentioned strontium and molybdenum in the same question. I assume that the question is partially driven by aquarium products that contain both strontium and molybdenum. There is absolutely no reason that I can think of why these two elements would be bundled together. Strontium is depleted by calcification, and molybdenum is a co-factor in certain enzymes. They have nothing to do with each other, and the aquarium products that contain both in fixed concentrations relative to each other are, in my opinion, irrationally formulated.

You also have a question about strontium testing. It can be done, and it can even be done by differential precipitation and titration, as in the hobby-level test kits, but none of those test kits appear to give consistent results. To work properly, these test kits would need to be carefully calibrated at many temperatures, and you would need to know, to a good degree of precision, what the exact temperature of the sample is. Without that, differential hydroxide precipitation and titration methods for strontium are doomed to fail, because the solubility of calcium hydroxide is such a strong function of temperature. (And you always wind up with some residual calcium ion in solution.)

Also in my opinion, the only feasible way to get calcium and strontium into the system in the 100:1 ratio depleted by coral calcification from NSW is to put the two into the water in that concentration ratio. That means using a base material that has them in that ratio. Dissolution of reef-based limes in a calcium carbonate/CO2 reactor is one way to achieve that objective. In terms of the formulated liquid calcium+alkalinity supplements on the market, to the best of my knowledge, only C-Balance contains a Ca:Sr ratio of 100:1.

Is strontium and important ion in a reef aquarium? Unfortunately, the stringently controlled experiments needed to address that question have never been done. So we are left fishing through the scientific literature for clues. The literature is a bit murky on this subject. A case could be made for the possible importance of strontium, and a case could (and has been made) to the contrary. Unfortunately, the "contra" case used a lot of emotionally-charged language like "poisoning" calcification. In actual fact, strontium is kinetically slightly slower through the calcification apparatus, but at 1 mole percent (the natural seawater ratio relative to calcium) any slowing is perfectly negligible.

It is possible that strontium has an effect on nucleation of various "interesting" minerals in the aquarium, not all of which are calcium carbonate. Again, the subject has not been experimentally investigated to my satisfaction.

I guess my practical bottom-line on the subject is that strontium might be somewhat important, but it certainly isn't THE most important thing. If you are concerned with it, then the best way to keep strontium in the tank is to lock its rate of addition to the rate of calcium addition. The two practical ways of doing that are to use reef-derived calcium carbonate substrates in a calcium reactor, or to use C-Balance.

Craig
 

dobish

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....thanks guys for the discussion...this is good info IMO and I hope others will pay notice to this thread....

....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>
 

randy holmes-farley

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As far as I'm concerned, there are 5 things that all reefers should measure; temperature, salinity, calcium, alkalinity, and pH.

If you have a problem, then many other things come into play depending on the problem. Magnesium, phosphate, silicate, nitrite, nitrate, ammonia, etc. all have their importnat uses. In an apparently healthy reef tank that is more than 6 months old, only the 5 above are what I would call mandatory.

I add a variety of things to my tank (iron, silicate, and iodide to the tank, and bromide and fluoride to the salt mix). IMO, no one "needs" to add these, but the iron may be especially useful for those with macroalgae.
 

CraigBingman

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dobish":em1vmzkx said:
.
....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
 

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