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FAQs about Marine Substrates: Aragonites

Related Articles: Marine System Substrates (Gravels, Sands) by Bob Fenner, Marine Substrate Options by Sara Mavinkurve, Deep Sand Beds, Live Sand, Biofiltration, Denitrification, Live Sand, Live Rock, Biominerals in Seawater, Understanding Calcium & Alkalinity

Related FAQs: Marine Substrates 1, Marine Substrates 2, Marine Substrates 3, Marine Substrates 4, Marine Substrates 5, Marine Substrates 6, Marine Substrates 7, Marine Substrates 8, Marine Substrates 9, Rationale, Selection, Reef  Substrates, By Type:   Coral Sands, Silicates, Dolomites/TapAShell, Southdown & Such, Collecting Your Own, & Physical Make-up, Size/Grade, Location, Depth, Marine Substrate Cleaning 1, Marine Substrate Cleaning 2, Moving/Replacing/Adding To, Marine Substrate Moving/Replacing/Adding To 2, Substrate Anomalies/Trouble-Fixing,


Named for the type locality (Aragon in Spain), Aragonite is a three-dimensional form (orthorhombic) of carbonate (the other principal form is Calcite... not very soluble). It's formed by biological and geological processes, and generally mined, crushed and graded for aquarium use, though it can be collected in the ocean (oolitic beds in the Bahamas are huge).



Aragonite Sand in Virginia Beach 6/12/12
Had no luck at my local hardware stores locating sand, went to a neighborhood weed & feed (Virginia Beach feed & seed) They were out of stock but according to catalog it is silica free and from the Caribbean
So I placed an order for a 100lbs for $12.58 it should be in Thursday Will let you guys know the outcome of the vinegar test
<Sounds good.  James (Salty Dog)> 

Oolitic Aragonite 4/16/10
<Hello Ann>
I am not sure if I am addressing my query to the correct email address but I had Anthony Calfo in mind.
<No longer with us.>
My son is building an institutional marine tank in Pennsylvania and he asks where is there in Pennsylvania a good source to purchase live rock & fish.
This would be a mail order.
<Might try Premium Aquatics located in Indiana. They are reasonable. Go here.
Do you also know of a cheap source of dry oolitic aragonite sand the size of sugar?
<Try same site, may want to Google.>
<Cheers, James (Salty Dog)>
Oolitic Aragonite 4/16/10
<Hi Ann>
Thank you James, I appreciate your quick response and will do what you suggest.
<Yes, do take a look. They are good people to work with, shop there all the time.
James (Salty Dog)>

Aragonite 3/9/9 Hi Guys <Hello Nemo's janitor.> Hope you guys can help me find the answers I am looking for. But before we go there I must first add that I have in excess of 15 years reef keeping experience with about a total of 45 years in the fish keeping hobby. Just a little background so you understand my experience. My questions to the team are. How do I determine what products have or are Aragonite? <#1 That's simple: Ask the producer. #2 Find out where the material comes from, what it is in terms of origin: older carbonate fossil materials are mostly calcite, younger materials (corals, shells) and younger precipitated rocks ("Tufa") are mostly aragonite. #3 More detailed analysis requires some knowledge in mineralogy, the crystals are quite typical, but you'd need thin sections, a good microscope, some experience to be sure. #4 In addition, calcite has a smaller density (<2,8 t/m³), so if you can determine the exact (!) density (+- 0,05 t/m³) you'll also be able to determine, which mineral you have in front of you.> Now I have done a little research on the subject and without going into detail have ascertained the following in simplified terms. 1) Aragonite is calcium carbonate (CaCO3) as is Calcite and they are polymorphs. <Yes.> 2) Aragonite will over time become Calcite. (Q for another date. Is there an in-betweens stage?) <Yes, in geological times of thousands, millions, 100s of millions of years. There are animals that can produce both minerals in their shells, geological units where only a part of the aragonite has turned into calcite, but the crystals themselves are either orthorhombic or trigonal.> 3) Aragonite has a Orthorhombic structure and calcite and Trigonal Structure. <Yes.> 4) The structure basically determines the hardness of the calcium carbonate or for its ability to increase the calcium content into the water chemistry at a reasonably high PH. <Yes, structure somewhat determines solubility, but solubility of both minerals is quite similar.> Is my understanding correct so far? <Yes.> I can go on providing cert's of various Calcium carbonate products mined throughout the world. All are meaningless to the layman/average reefer. Me included. Hence my inquisitiveness. From these Chemical analysis sheets how does one determine what is suitable for aquarium use. Most probably both. <It cannot be determined from analysis sheets alone in every case, only if the density is given.> But which are aragonite? If any. <Likely both below are calcite.> I submit 2 arbitrary Cert's for your consideration. Comments on if you were an aquarist what to look for. 1) http://www.sudeepgroup.com/calcium%20carbonate%20(hc)%2098%20%25_granular.pdf <No density given.> 2) The product here is The Juraperle. You will find it under downloads. http://www.eduard-merkle.de/ <This is calcite, I know the geology of the quarries of this company. They also give the density which confirms this is calcite.> There may well be articles covering the subject and I apologise intruding and taking your time. Please point me in the right direction. Your input would be appreciated. Many thanks Nemo's Janitor. <For use as aquarium substrate I'd simply prefer (oolithic) younger aragonite sands due to their surface structure. For use in Calcium reactors it does not matter if the material is calcite or aragonite. Their solubility is quite similar (solubility of aragonite is larger), the surface structure will be much more important here, too. The more porous the medium is, the larger the surface, the better the kinetics of the solution process. A simple look at the grains will be more helpful than an analysis if this is Aragonite or Calcite. Cheers, Marco.><<Dang! RMF>>

Aragonite, but Which Adam..??  11/30/05 Hey Adam <Hello?> I would like your opinion on aragonite as a substrate as I've never bothered to incorporate a substrate, I have no idea which one to purchase. <Well first you need to decide why you want substrate. There could be a number of reasons to incorporate substrates in marine aquaria; aesthetics, to enjoy the benefits of a Deep Sand Bed or creating a certain type of biotope or living environment (i.e. resting spot for wrasses). As for aragonite it is calcium based making it useful for its buffering effects in the marine tank. The problem with it is that most hobbyists choose a brand that is too coarse and thus it becomes a nutrient/detritus trap. I would attempt to find material that is as fine as possible. Another thing to consider is the flow rates within the tank, tanks such as high flow shallow water biotopes can make sand beds quite impractical.> Thanks. <Adam J.>

Aragonite by any Other Name... 10/28/03 Anthony,  I was at the Atlanta seminar all thanks I picked up a lot from you. <very good to hear, my friend> There was one point I caught half of and was wondering if you could give me a short recap about Sand. Types, where it comes from, Basically what you informed us at the seminar. Thank You <very well... essentially all aragonite (oolitic) sand comes from the same source. By composition (versus calcite), aragonite is very limited. So... if you buy such sand from a DIY lumberyard as play sand... or if you buy sexy packaged aquarium sand... they are still the same product. It can be sifted, sorted, graded, rinsed, etc... but its still the same aragonite. I prefer the DIY source sand not only because its inexpensive, but because it is unwashed. Rinsed sands often have more (yes, more!) impurities in them for having been processed in/on metal aspects (trucks, conveyors, under dryers, etc). Chemical assays of the media reveal this to most folks amazement. The chalky silt from unwashed sand is also a great benefit to water quality as it dissolves easy. You simply have to tolerate a few extra days of cloudiness to the water. No worries :) Anthony>

Pure Aragonite Sand - 2/23/03 I have read Dr. Shimek and 1300+ Southdown posts. <Makes a man out of ya> Do you have any experience with  "Pure Caribbean Aragonite from Petroglyph"? "Grain sizes vary from 0.18 to 1.2mm, perfect for reef systems." Allegedly oolitic. <Actually, I use Nature's Ocean oolitic in my 30g Indo Pacific lagoon tank. A little expensive but I really like the results.> They sponsor some web sites. <Yes, very good about supporting the industry.> I would be having it shipped in and need about 280lbs. <are you doing a 4 to 5 inch deep sand bed?> I have Googled your site with no luck. <Hmmm.......you're right don't see it anywhere........in any event I am sure it is a fine product. Check out the many aquarium forums and see if anyone is using it in their tanks. Get some opinions/reviews. In any event, I like their aquarium calculator tool for finding the pounds needed for sand bed depth in an aquarium. Good site overall. Thanks for the link. Paul> http://www.purearagonite.com/facts.html

Aragonite sand  - 2/15/03 HI Bob , <Anthony Calfo in your service> Is Southdown sand considered fine sand? <yes... sugar-fine oolitic/aragonite> and is it good to use for a DSB. <the best in my opinion at 4-6" or more> I have a fifty five gallon tank with about 3 inches of Southdown sand. <That would be the minimum for efficient denitrification IMO> Some corner areas are turning black . Is this normal ? <Yes, likely... unless you notice a sulfur smell (rotten eggs) which often indicates a lack of good water flow and/or stirring in the tank> .Tank has been running for 4 months.    <Ahhh... no worries, the tank is too young to go anaerobic without extreme neglect (not likely here). The coloration between the glass in sand is limited to that thin film/area and is from indirect light causing dark algae> I was going to raise this to 5 inches this weekend . Do you think this is a good idea or should I leave it the way it is and get more sand sifters? <Both if the sand sifters are hardy (like bullet/dragon gobies or blue-spotted yellow watchman gobies> Thanks  Chris <best regards, Anthony>

SW substrate dust... new... in the tank Hey guys, I'm starting a reef tank, and I ordered some aragonite sand on the internet. It didn't say anything about washing, and after I put it in and filled my tank, I found out you are supposed to wash it. <What a mess!> My tank is 29 gals and I have an Aqua C protein skimmer with a maxi jet 1200. I just started running the skimmer a couple hours ago and the tank is still really cloudy. What should I do? Will this clear up over time? Thanks for all your help Sincerely, Devin O'Dea <Mmm, if it were me, my system... only twenty some gallons of water... I'd dump it all out, rinse the substrate in clean bucket increments (about ten pounds at a go) and start again... you will lose at least this amount of water trying to gravel vacuum out the dust... and the time waiting... Bob Fenner>

Substrate Choice Hello! :0) Bob and Anthony <cheers, my friend> To Anthony I have to first say this; I read your account with an individual who was trying to shoehorn a metal halide between two fluorescents in an improper shroud design.  You may or may not recall.  I was laughing so hard I damn near lost my bladder.   <ah, very good to know. I have always felt it important to include spastic and involuntary incontinence as part of the everyday> You have missed your calling, you could easily write comedy.   <heehee... thanks kindly for saying so. I really do look for reasons all/every-day to laugh. Delighted when I can share it> I would also like to say that I have your book "Reef Invertebrates", excellent tome'.  Now, my question finally.... I have a 180 half cylinder, (I know, you recommend long and low) <truly no worries as long as you don't stock it like its a low/long 180. Just be mindful of the surface area/gas exchange limitations of tall tanks and all will be fine> that will have a 55 gallon sump, and two 55 gallon refugiums upstream.  I will place my DSBs remote in these vessels.  I like the idea of being a "ball valve" away from isolation should things go wrong.   <understood... although the risk is small for the need to take them offline. The keys are water flow and nutrient control> Since I am setting these remote items up this way I was wondering if I could use a different substrate in my aquarium that will not absorb overtime.   <hmmm... by absorb, do you mean become a "nutrient sink"? If so, then opt for finer substrates as more coarse media requires even greater water flow and stirring and/or siphoning> I will be running the DSBs remote and I will be running a Calcium Reactor.  I do not want to replace sand in the main display over time.   <then opt for fine calcite not aragonite> I only wish for a non-replaceable aesthetically pleasing substrate.  What depth and what substance would you recommend that would be low maintenance?   <only about 1/2" or less> My tank turnover will be between 20 to 25 times an hour to the sump. Mike <all very fine to hear. Rock on my salty brother. Anthony>

UGF plate in tank to create denitrification Bob, We've spoken recently regarding my new tank set up using RUGF <Reverse Under Gravel Filtration> with Crushed coral as substrate. I'm a newbie. As I keep reading up on all this stuff it seems that denitrification is one of the hottest topics when it comes to marine tanks. My question is.......instead of my original plan of a RUGF with Crushed Coral.....if I just use an UGF plate in my 75g FOWLR w/a few Shrooms and softies, and use 1 1/2 of Crushed Coral, will it create a denitrification zone in the tank? <To some degree... would be far more effective with a deeper substrate level, depending on grade, three, four inches> And would regular aragonite sand be better vs. the crushed coral? <Of same average diameter, no> I'm not sure I know the difference between the two (CC vs. Aragonite) other than one is a larger size than the other but they have the same chemical make up. <Actually... aragonite/s are mined, consistent composition... calcium carbonate... crushed corals are collected inorganic matrices of organic origin that contain considerable "impurities" of use... like magnesium.>   I'm reading where CC seems to be a substrate that buffers well and holds the ph constant among other things. What do you think about denitrator units?   <... am a big fan. Bob Fenner> Thanks Don

The Sands of Time...(Sandbed Dissolution Rate) Hi guys, <Hey there! ScottF. with you today!> Have a question regarding substrates.  Starting my tank and have a 4.5" DSB with pure Caribbean aragonite.  I have been reading that aragonite dissolves quickly.  My question is how quickly? <To be quite frank- I don't know of any study that has been done that revealed specific rates of sandbed dissolution in closed systems. There are a lot of factors that come into play, such as the ph, alkalinity, etc. Suffice it to say that Aragonitic sand beds will "passively supplement" (as Anthony would say) your calcium level over time with this dissolution process. However, I'd suspect that this will occur over the course of a year or so...Try making a mark at the top of your sandbed (in a location where it is unlikely to be disturbed by digging fishes, currents, or maintenance activity), and then glance at it on a regular (like every few months) basis to see if the sandbed depth has decreased. this is, admittedly a crude, unscientific method, but it may give you some idea> I have a 75 gallon tank.  I was doing some reading in Anthony's book and he suggests a DSB of 5-6" b/c of this.  Also, when and how should this be replaced to keep at a 4-6" depth?    <Again, I'd "mark and measure" periodically to determine when you need to add more sand...I'd simply add it on top, and spread it around carefully...Nothing to fancy! Hope this helps! Regards, Scott F>

Sand bed questions Good afternoon guys, hope all is well. <Very fine, thanks and I hope you are well too. Anthony> I have had to dose the tank heavily with calcium recently and have realized that I probably need to replace the sand bed after two and a half years. I have about two-three inches of aragonite and now understand that wasn't an optimal depth.  <yes...under three inches in my opinion is very challenging to maintain successfully. Almost impractical to have enough detritivores, water movement, etc. to compensate and prevent it from becoming a nutrient sink> I would like to replace it with live sand. One of my goals is to reduce nitrates.  <then a DSB with sugar-fine aragonite may be your ticket> I have a thirty seven gallon with a new CPR refugium and a Remora skimmer. So if I add about 1/2" in the main tank with 4"-5" in the refugium will that reduce nitrates noticeably? Currently they range from 10-40.  <I seriously doubt that the CPR sized refugium is big enough> I have a B. Cardinal, damsel and Pseudochromis in the tank now, but are only going to keep only the cardinal. I would like to change the tank over to mostly soft corals, with a pair of cardinals. <lovely... and if you are not afraid of them <wink>, do consider a long-spine blue dot urchin (reef safe-yes) if you get a bigger tank to grow up and let the cardinals live naturally among the spines> I currently have Kent bio-sediment in the refugium, would it be best to remove or could I mix with live sand to add extra mineral content?  <I might leave well enough alone (definitely not an endorsement of the Kent product though). I don't subscribe to mixing "magic mud" products and sand too much> I read several categories of the FAQ and it seems that you guys recommend changing half the tank at a time. Would it be a disaster if I did it all at once?  <rather challenging. I prefer to do it that way, but am hesitating to recommend it. I have more time than most people with real jobs to spend on my tanks <G>.> Or maybe the refugium then tank? It is going to be a huge project that I would like to do all at once. On another note I just purchased a R.O./DI unit and notice that I get a lot white sediment when I prepare the water.  <are you aerating it first to drive off the carbonic acid? if not... wasting a lot of buffer and creating insoluble bicarbonates(?)> I usually take about seven gallons add Kent Superbuffer dKH and let it sit a couple of days to come to temp., then add salt. Is this a good method?  <sounds like no aeration. With DI or RO water, it must always e aerated before ANY kind of use afterwards (fresh evap top off, or making seawater)> I guess that the sediment are minerals from the buffer? As always thanks for your help. Lowe <quite welcome. Kind regards, Anthony>

Thermometers & Substrate I have 2 questions for you all today 1. which is better as far as thermometers go the glass ones that go inside the tank or the sticky ones that go on the outside? <IMO, the glass ones are better, but should not be allowed to float around in the tank waiting to get broken.> 2. When I bought my substrate (crushed coral) the guy at Elmer's LFS said NOT to rinse it, but the bags say to do a light rinse. <Crushed coral needs rinsed like crazy.> Which is right? <Are you sure you have crushed coral though. Being from Pittsburgh and knowing Elmer's, I am not sure they carry crushed coral anymore. They do have various grades of sand, some larger than others.> It is not live sand. Thanks, Colleen Pittsburgh, PA <By the way, did you make Bob's pitch at Elmer's on Saturday morning? -Steven Pro>

To Rinse or not to Rinse III Ok I'm home now have set up the tank did rinse the substrate and the bags did say "aragonite grade crushed coral" there is like tiny shells and stuff in it. Not sand for sure. With three bags the base is about 1" in my 75 gal tank. Everything is up and running figure I'll let it go till tomorrow and take more salt readings and pH and then decide what I'm going to do next a little damsel or 2 or just some live rock not really sure yet. ~Colleen <I would strongly suggest the live rock cycling method. You can read more about this on WWM. -Steven Pro>

The Opinion of Aquatic Experts Hello WWM Crew, I have a couple of questions. Is it true that you should not have a big bed of aragonite? I have 270 lbs of Aragonite in my 180 gallon tank and have been told by 2 different people that I should remove it and replace it with crushed coral since the Aragonite will turn into a mush and retain all sorts of nasty things. <Definitely not what I would do. I prefer to use a deep sand bed, 4" or more of fine aragonite sand.> The other thing they said is that I should not run the skimmer 24 X 7 that I should only run it a couple times a week or that otherwise the LR won't get the nutrients that it needs, this was told to me by two supposedly "Aquatic Experts". Is this true or are they just out of their minds? <I strongly disagree on both counts. Do not just blindly follow my opinion or recommendations. Get the advise of others. Read books, magazines, and online chat forums to formulate your own educated opinion.> Once again thanks. <You are welcome. -Steven Pro>

Aragonite I have a 75 gal trickle overflow with a 20 gal sump that is large enough to handle a 15 tank and is working good water spec are great the only problem I have is that my ph stay at 7.9 or 8.0 I add Kalk by slow drip but after the one gal bottle empties it goes back to the 7.9 - 8.0 I would like to know if the original aragonite that I put is the tank eventually loses its punch  <All substrates do> or may be I don't have enough  <A distinct possibility> got about120 lbs live rock I got about an half inch under the rocks and about one inch and a half in the front of the rocks fine to med grain should I had more and if so how much do you think this would help I have a med to heavy load of live coral and about six small fish would increasing the amount on the bottom be the solution THANKS <Maybe... but look into more of your background in water chemistry here... You'd be better off with a "two part" supplement system to bolster your alkalinity (give up the Kalk)... and best with a simple calcium reactor. Please read over these areas on our WWM site, starting here: http://www.wetwebmedia.com/watrqualmar.htm and onto the many linked files, FAQs listed. Bob Fenner>

Changing substrate & time Dear Bob, After hassling with a hair algae problem for about 1.5 years, and talking with various experts at several different locations, (you inc.) I decided to change out my substrate to a mixture of Carib-sea Aragamax and FFE live sand. After about 15 hrs. of extreme TLC and many words that are not printable, the task was completed. <I hear you> It has now been 3 weeks to the day, and the results are great. There is no re-growth of hair algae to speak of, and the 2 50 gal. cleanup crews, (thank God for turbo-grazers) <And the hair algae...> , are taking care of what is left. All my corals and other finny critters are doing fine, after what must have been a very traumatic experience for them. My question (questions) is, would this be like setting up a new tank? <Yes, in most respects> I re-used quite a bit of water from the "old" system to refill the tank after the process was complete. All the LR was scrubbed with a toothbrush to remove the nasties. How long should one be expecting to wait to see if this changeover actually worked? <You have seen it> 80 gal. tank. water parameters all good except the iodine level 0.04 ca @ 400, alk. 9-10, mg. 1300, nitrate<10ppm. Oh yeah, one more thing. I have recently been seeing where the addition of "Kalk" is not exactly the thing to do. <About time... I've been against this archaic, toxic practice from day one...> A friend of mine has been using a product called "Aragamite" from Carib-sea to do her buffering and calcium adds. What do you know about this product and it's results? <Yes... basically (pun intended) it's finely ground "old reef"... in effect, much like wave action in the wild, many calcium reactor designs... Bob Fenner> Thanx for your input, Charlie Ehlers.

New tank...need advice Dear Bob, I visited your website and I found it the most useful marine site out of the dozens or so I'd encountered. I currently have a AGA 72-gallon bow front aquarium. I'm planning to set-up a reef tank with soft corals with various invertebrates and fish. However I need some advice on the equipments I will need in order to make this system successful. I plan to use Instant Ocean Sea Salt and lay 40 pounds of Carib-Sea Live Aragonite Sand (1-2mm) on the bottom of the tank (hopefully this will be about 1-2 inches).  <40 lbs of sand will barely make an inch, in that tank. Personally, I'd mix the live sand with the finest aragonite (dry, but carefully rinsed) that you can find, if you're looking to save a few dollars. But the trade-off is that rinsing the dust out of bagged aragonite is agonizingly tedious...and you won't have to do that with the live sand.> I have a Hagen Fluval 404 canister filter, Hagen Aquaclear 300 power filter, Hagen 200 watt Tronic-Electronic heater, AGA twin tube light hood, CustomSeaLife PC Hood(110 watts) w/ 2 SmartLights, and I'm planning to buy a CPR Bak Pak 2 protein skimmer.  <Those should cover you fine, if you're careful to let the tank cycle slowly and completely, before you start stocking like crazy...> I also plan to buy a mixture of live rock mixed with Tufa rock, with Tufa rock being more abundant as I'm on a tight budget.  <That's fine. Again, go slow with the stocking plan. Within months, your Tufa will start to look more and more like your expensive live rock, and in a couple years, you can't tell the difference.> In addition I don't exactly know how many powerheads I should use and at what rate each of them should be at. What brand of powerhead would you suggest?  <I like to use 4 power heads in a 48" tank, at each end, pointing toward the middle. I tend to use RIO 800 or similar for that application, but the Rios are starting to get on my nerves. Replacing suction cups every few months...> Can you please tell me if I have adequate equipment for the system to work and any additional information or advice? Thank you so much!!!! P.S. How should I clean the Tufa rock and about how long would I need to cycle my tank before adding any livestock? Thanks for your help!!!!!!!!!!!! <You can just rinse the Tufa real well with hot-hot water in the shower or bathtub, some folks (obsessive?) will go so far as to boil it. Not me. As far as cycling/setup, I'd let the tank sit with the filtration and substrate for 24 hours, then with the Tufa for 24 hours, then start adding live rock (I don't like to add more than about 20 pounds every 24 hours). Then a couple small fish, for 2-3 weeks, with testing for ammonia/nitrite/nitrate, to observe the actual cycle. Don't put your 'show' fish in there for at least 4 weeks from day one, if you can hold out! -Lorenzo> Peter

Changing gravel Hi Bob Fenner, I've got a 55 gal Berlin system, with ~60 lbs live rock, setup for about six months. I want to change the substrate from aragonite gravel to a much smaller aggregate aragonite sand. I've already exchanged 1/3 of it a week ago, now I'm considering changing the remaining 2/3rd's in one shot. I fear losing the bacteria from the gravel will cause ammonia or nitrite spikes. I have a fairly light bio load with a total of 9 fish, the largest two being a 3" Hippo and 3" Coral Beauty.  >> Don't be overly concerned... the odds are vastly that you won't experience any noticeable amounts of nitrogenous intermediates... the live rock has much more biota and response than you'll very likely need. Not to worry. Bob Fenner

Re: anemone I guess aragonite is too coarse? I just read your message again. >> <Aragonite is a generic term... in disuse... referring to any easily soluble calcium carbonaceous material... if it is fine enough, no problem... something more than 30 pieces per linear inch (sand) is what I'm referring to... Bob Fenner

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