deep snad bed?

[Bifferwine]

Team Randy.

[Alexander]

Dom i remember seeing pics of the old tank.... .not sure if it was with a dsb but holy crap it was crazy overloaded with growth. wasnt that the same tank that you had that MASSIVE colt coral that was practically growing out of the water?

[fatman]

Originally Posted by ccCapt

This may be of some interest.

Chemistry and the Aquarium: Calcium By Randy Holmes-Farley

....Consequently, aragonite first becomes soluble in seawater when the pH drops below about 7.7 (this value might be more like 7.5-7.7 in reef tanks where the alkalinity is often higher than in seawater). That level is attained in some sand beds, and permits the dissolution of some of the sand.
The rate of dissolution is fairly low, however, because the rate of delivery and degradation of organics (or certain nitrogen compounds) deep enough in the sand to permit a pH drop is fairly low. The rate will, however, vary from tank to tank as the different ways of delivering organics to deeper parts of the sand will vary (diffusion; movement by organisms; death of organisms, etc). Note that the need to oxidize the organics in deeper parts of the sand to permit dissolution of the sand has nothing to do with the oxygenation of the sand. It has more to do with the fact that at near surface regions of the sand, the pH will be closer to that of the tank water by acid and base transfer from the water column, and you need to be deep enough to permit a lower pH to become established.

I have no reason to believe Anthony Calfo is lying, nor do I believe Bob Fenner is lying about at what temperature aragonite starts dissolving. Nor do I doubt the thousands of people who openly have shared their experiences in this regard. I also do not think thousands of commercial growers would still be following their Calfo and Fenner's recommendations if they were wrong and you were right. I do know that the pH's given above are the pH's in which crushed coral (calcium carbonate dissolve) not aragonite. Aragonite dissolves at a higher pH as it is geometrically different from calcium carbonate. This is not new information and I fail to see why you feel a need to argue about it. Aragonite dissolves starts dissolving at a pH of 8.2 and dissolves faster at even lower pH's that are experienced in the deeper levels of a deep sand bed. Speculation as to why that pH is lower at depths is still ongoing. I do know that a deep sand bed fed no nutrients has a low pH at depths as does a deep sand bed fed nutrients. Am I saying Randy-Holmes Farley is wrong. No I am saying he speculates as do others. I believe he believes he is right, or at least at the time he wrote that article. I am sure his speculations were based upon his experiences and training and hopefully what he learned from others. It is the same way with other experts in the field. Some are pure researchers and some are mainly practicing commercial growers/aquarists with educations and professional experiences in the aquatic field. Would I believe a pure chemist over Randy-Holmes Farley as to when aragonite dissolves in sea water. That is very likely. I know also for a fact that I keep my display tank at a pH between 8.3 and 8.6 and my aragonite still dissolves and I have no fish in my display tank leaving large amounts of detritus and I have very high circulation but there is obviously no diffusion of oxygenated water to the bottom depths of my deep sand bed. The material you have posted is probably pretty old as it is obviously dated, and it is contrary to fact in some obvious ways. I have no reason to be lying about this and I doubt Reeffreak, Calfo or Fenner have reason to lie about it either. I do not believe we are wrong as the facts of the disappearing aragonite sand sorta speaks for it self. Also you must consider a good majority of the calcium is removed with frequent water changes.
I have just gone to the site you posted the link to. It clearly repeatedly refers to calcium carbonate. Repeatedly, repeatedly, repeatedly it refers to calcium carbonate. That is what the article is about. The fact that at one point he mistakenly refers to aragonite as dissolving at the same pH as calcium carbonate is understandable as the whole rest of the article is about calcium carbonate. They have the same chemical formula but they do dissolve at different pH's in sea water. They are structurally different. Crushed coral is calcium carbonate and it does not dissolve at normal marine tank pH's. Tht article is also at least 6 years old. The information and books as well as my recent experiences are all much more current. Anthony's book is less than a year old. And the wet web and RC articles and threads are less tha two years old at most. Some might infer something from this.

[ccCapt]

I didn't even bother reading your whole reply. I got to the part where you still say....Aragonite dissolves starts dissolving at a pH of 8.2.

I showed a reference from a well known and published chemist, yet you still say otherwise. Should I believe someone who has published countless articles on aquarium reef chemistry, or some dude from Alaska who spews nonsense and gives no references to back it.

Sorry Fatman, you lost any credibility you may have have as far as I'm concerned.

[cumminz]

I read his whole post. go read it. It says that It clearly repeatedly refers to calcium carbonate. Repeatedly, repeatedly, repeatedly it refers to calcium carbonate. That is what the article is about. it is not about Aragonite. it also says that it is over 6 years old, which as You and i both know, Alot can happen in 6 years. Go read his post. Don't criticize him if you wont hear what he has to say.

[ccCapt]

Originally Posted by cumminz

I read his whole post. go read it. It says that It clearly repeatedly refers to calcium carbonate. Repeatedly, repeatedly, repeatedly it refers to calcium carbonate. That is what the article is about. it is not about Aragonite. it also says that it is over 6 years old, which as You and i both know, Alot can happen in 6 years. Go read his post. Don't criticize him if you wont hear what he has to say.

LOL Please do some research before running your mouth.
What is aragonite?
From Wikipedia, the free encyclopedia.
Aragonite is a carbonate mineral, one of the two common, naturally occurring polymorphs of calcium carbonate, CaCO3.
Massive deposits of oolitic aragonite are found on the seabed in the Bahamas.

Aragonite IS calcium carbonate.

[cumminz]

Again, straight from Fatmans post....The fact that at one point he mistakenly refers to aragonite as dissolving at the same pH as calcium carbonate is understandable as the whole rest of the article is about calcium carbonate. They have the same chemical formula but they do dissolve at different pH's in sea water. They are structurally different. Crushed coral is calcium carbonate and it does not dissolve at normal marine tank pH's..... they are made from the same thing, just structurally setup up different

[fatman]

Originally Posted by ccCapt

LOL Please do some research before running your mouth.
What is aragonite?
From Wikipedia, the free encyclopedia.
Aragonite is a carbonate mineral, one of the two common, naturally occurring polymorphs of calcium carbonate, CaCO3.
Massive deposits of oolitic aragonite are found on the seabed in the Bahamas.

Aragonite IS calcium carbonate.

Some people expend great deals of energy trying to climb over a glass wall just to see what is on the other side.
Yes, aragonite and calcium carbonates are polymorphs. They dissolve at different pH's due to that fact. Calcium carbobate is not aragonite and aragonite is not calcium carbonate. They are different geometrically (differing crystalline structures). I do not know why Bahama oolitic aragonite deposits is now being discussed by you. Diamond and graphite are a pair of polymorphs, are you also going to say the are the same degree of hardness. Physical properties such as differing crystalline structure effect things such as hardness, and at what temp they melt or at what pH they dissolve. Calcium carbonate is not aragonite and aragonite is not calcium carbonate. Saying something is a carbonate mineral is not the same as saying it is calcium carbonate. For an exa,mple sodium bicarbonate is a carbonate but it is not calcium carbonate. Just as a diamond is madeof carbon as is graphite., but graphite is not a diamond. They are polymorphs.
If you can not be civil then you should limit this eduactional experience to PM's.

[cumminz]

I got Your back Fatman. You have given me some good help in the past and i agree with you brotha

[ccCapt]

This discussion is drifting way off track. I quoted a published article by a well known chemist, and you decided he used the wrong word and that he speculates.
For the sake of this discussion, let's forget about what pH aragonite dissolves and the different structures of the many forms of calcium carbonate.

This is the statement I question.
Aragonite sand only has a half life of about 8 to 12 months, so am putting a new bag of sand in my tank at least once every month to two months at most. It looks like it settles, but it actually dissolves.

So being 1/2 the sand will be gone in 12 months, if I buy a brand new 40 lbs bag of sand and let it sit in my basement, in 12 months I'll have 1/2 a bag? Or does it have to be in seawater and now the 1/2 life is affected by other circumstances? Will it be different if I put it in freshwater?

OK, for the sake of this discussion, say 20 lbs/month dissolves. Where does it go?
However, the calcium, strontium, cabonates and magnesium that make up the sand does enter the water mix so it is not lost, it is used by corals and coralline algae for growth.
That would be some massive growth in a month. But wait....
I have never heard anyone using a deep sand bed say the dissolving sand contributed to much acalcoum, carbonate, magmnesium or thorium to their systems.

Is it used by corals or does it not contribute to the system?

Where does it go? How about this statement?
Also you must consider a good majority of the calcium is removed with frequent water changes.

Now water changes are being done to LOWER calcium levels? Why bother adding calcium to any system when water changes are needed to get it out?

Let's stay on track fellas.