Hi Tom,
I have a couple of questions for you. I'm going to install a plenum in my 75 gal system II reef tank, my LFS (local fish store) says I should use crushed coral for bottom layer of sand so it won't clump. What's up with that? Also, they say I should distribute sand in two even layers. I read Marine Fish Monthly and enjoy all the articles. By the way, what happened to "Simply Speaking?" I really liked it. Thanks for your wisdom.
Mark
Mark,
Thanks for the note! Glad you like my "Simply Speaking" column in Marine Fish Monthly. I was just too busy to make the last issue. Will be back this next time. As for clumping and aragonite sand. Most people still don't get it!!!! Correct information and good advise about the use and care of aragonite sand is not very abundant. This is one of the most common questions I get. Repeating some of the "gurus" is popular and very fashionable these days. Incorrect information abounds for this reason and aragonite sand continues to be misunderstood by way too many. Even "chemists" argue about this, but in real actual everyday practice you may notice exactly what I will tell you below. Theorize all you want, but in real life, aragonite sand use differs from some "theories".
First and most important, the ONLY reason aragonite sand clumps together is from inducing that clumping your self. Surprised!? That's NOT what you've heard elsewhere, right? Yes, YOU are the one who has to induce clumping, either consciously or not. NO EXCEPTIONS! If YOU don't want your aragonite to clump then YOU can actually choose to keep it from clumping, but only IF you know why it clumps. It does not naturally clump in marine tanks, and does not clump in nature. This isn't because of all the extra worms and stuff on the wild reefs digging in it - that's BS!!! That will help someone sell you more stuff though ;-)
How does aragonite sand clump then? Answer: By adding too much KW (kalkwasser), buffers or two part calcium additives. Simple as that! By doing so you kick the KH/Alkalinity up too high and then the calcium precipitates out of the water and forms calcite in and among the sand grains. Aragonite sand really has an affinity for this, unlike many calcite based crush corals. So, you can keep your sand from clumping by either having old dirty aragonite sand or standard crushed corals (calcite) to keep the aragonite grains apart from each other and from clumping together. However this does not solve the real problem! You will still internally bind each aragonite grain from being able to fully dissolve now, as it is coated with calcite which dissolves much slower than aragonite. Aragonite and calcite are both mineral/crystal based forms of calcium carbonate which dissolve differently. Just use 100% aragonite sand and forget about spending extra money to abuse it by using too much KW, buffers or two part calcium additives. Fine products like SeaChem's Reef Builder IS included in this group of common buffers, or clumping offenders
By the way, you can distribute the sand layer/layers above your plenum layers in any thickness you want. If you choose you don't even have to divide the sand into two layers. A thicker sand layer (or sand layers) over the plenum does have advantages though. I like tp use at least 4" of sand over the plenum usually. The sole purpose of the diver screen in the center of the sand, or above the center, is to keep diggers from burrowing too deeply. Jaubert simply put his sand dived screen closer to the top of the sand to keep fish from digging too deeply. The aragonite sand grains average about 1.5 mm diameter in his tanks. If you don't have deeply digging fish or heavy sand stirrers then you can run a Jaubert plenum system just fine with NO divider screen in the sand. Many others and I have done this. I'm not much in favor of sand diggers anyway.
Well, these are the things that actually work in real life when using aragonite sand in your tank. You can play with the layering and grain size a bit, but NOT with high KH/alkalinity when using aragonite sand - they just don't mix. Let me know if they try to confuse you more
Tanks-
Tom Miller
Tom,
Thanks for the letter about aragonite clumping. I have another question for you, as you know I'm going to install a plenum in my reef tank, I need to know which type of CaribSea sand to use? Geo-Marine crushed coral, special grade aragonite reef sand, or sugar sized oolite? I'm going to use screen with layers as I noted in my last e-mail. Also I have a large green carpet anemone in my 75 gal reef tank with a large 3" Sebae Clownfish. The clown likes to stir up the sand pretty good around the anemone. Do you think he could be a problem? What about the anemone? Do you think he will try to dig to deeply to put his foot down? Will he upset the screen layer? Will the anemone sting corals I'm planning on getting? Thanks for any information in advance.
Mark
Mark,
I usually use only CaribSea special grade aragonite reef sand over plenums and it works very well. Three 44 lb bags of it will work about right for a four inch deep layer of sand above the plenum. Jaubert uses the same size aragonite for his, so I assume it must be pretty good. I didn't find that out about him until after I decided it worked pretty good for me. I have heard some, like Sprung and Perrin, say that GeoMarine grade is best. I like the finer size (special grade aragonite reef sand)mostly because it has more surface area for better dissolution. Oolitic, like AragaMax, might be so fine as to limit the water flow through the sand a bit more than I would like it to be limited. That seems to be why Sprung and Perrin go for the GeoMarine size sand grains which are twice the grain size of special grade aragonite reef sand. Perrin is sucking water through a portion of his very deep sand beds with UGFs, and I can see why he might benefit from keeping the water pathway open through the sand with the bigger sand grain size when forcing water to flow through it like this. He uses thicker sand beds of about 8 to 12 inches deep in some cases. Morgan Lidster of Inland Aquatics also uses very thick sand beds but without plenums to slightly accelerate natural water flow through the sand. Morgan uses at least four inches of oolitic aragonite right on the tank floor and then at least two inches of special grade aragonite reef sand on top of it. Most of his newer sand beds are thicker than this now. He has even used up to 20 inches of aragonite sand in one case. He made the first sand bed at Inland Aquatics with about 4" of oolitic aragonite sand on the bottom of the tank and then about a 2" thick layer of reef sand grade aragonite on top of that. This was about six years ago. He has had to thicken this sand bed back up since then, because it slowly dissolves.
Both Dick Perrin and Morgan Lidster depend on aragonite sand not only for nitrification and denitrification, but also for adding calcium and other elements to the water. Aragonite sand is very important in making their commercial coral farming companies successful and keeping cost down. I think they would both agree that aragonite sand is perhaps the most important ingredient for simplifying and making reef systems more successful. Others seem to contend that the protein skimmer is the most important element in a reef aquarium.
Your carpet anemone will dig into the sand and attach to the upper screen layer, or at least the carpet anemones I've seen have done this. It can dig past the first screen layer if it digs at the edge of the tank. Mine did not dig there so it couldn't really dig deeply. Yes, the anemone and clown could have some effect by digging this way, but with the upper screen layer being a bit higher than the middle of the sand (like I recomend placing it - and also found later that Jaubert does also), the anemone and clownfish shouldn't be able to hurt things much at all. This higher middle screen layer simply limits the depth of their digging. Still I preffer not to disturb my own sand much at all.
Also, the carpet anemone could sting corals, and is a potent anemone, having more "stingers" than other types do. It puts out more toxins in the water and you should pay attention to water changes, and maybe a bit more protein skimming and pay attention to carbon changes too. Carpet anemones are good fishermen also, if you get my drift. Some people have had them eventually clean out a tank of all fish, other than the associated clownfish. These problems have left many reef aquarists a bit unnerved. On the other hand, others have not had much problem at all with them in a reef aquarium.
Tanks-
Tom Miller