Saltcorner
By Bob Goemans
By Bob Goemans
Dear Mr. Goemans,
I have several questions to ask about the plenum system. First I would like to say I enjoy reading your monthly Sand Mail column in FAMA. I find it very helpful along with your various books. I am setting up a plenum system in a reef tank and am going to use aragonite for the bed material. For the 4 inch bed, does all need to be aragonite or can I mix, say 2 inches of live sand and 2 inches aragonite. I also understand aragonite dissolves slowly over time at a pH of 8.2, so eventually it has to be replaced, but how soon will that become necessary?
I also plan on using a calcium reactor with the system. Do I use the same formula to figure out how much aragonite it needs as is needed as with live sand? When the aragonite breaks down, does it release enough calcium, magnesium, strontium, iron, so that other additions are not needed? Lastly, where is the best place to order live sand or the aragonite? Keep up the great writing, I enjoy reading your articles.
Thanks!
Troy Steinberg
Hi Troy,
Thanks for your comment about my column and if you like the column, you should see my new website! Check it out at www.saltcorner.com. As for aragonite, it is the best choice possible for substrate in reef aquariums because it dissolves slowly adding some of the more important minerals. Notice I said 'some,' as it does not generally keep pace with system needs. For that a calcium reactor should be considered, or possibly a two-part solution. And even that may not add all the essential elements needed. Therefore regular testing is advisable, as are necessary additions of those needed elements.
As for substrate, the most important factor is sand grain size. Staying close to the 2 - 4 mm size is preferred. Mixing different type material, e.g., live sand, crushed coral, or aragonite is certainly acceptable. Again, grain size needs to remain in the acceptable range. And attention to the more course, angular shaped material is also preferable because it provides for better diffusion/penetration of oxygen. Much of the beach collected finer sands are more rounded, therefore restrict diffusion somewhat. They also contain organic material and probably some oil-based products. Aragonite sands now come prepackaged with 'live' bacteria! It's the way to go instead of some of these beach-collected sands. And, use of as much 'live' sand as possible will help establish microbial colonies more quickly. Its always wise to establish the users of nutrients first, than allow nutrients to accumulate while bacteria colonies are only beginning their colonization efforts.
As for eventual additions of substrate, the time will come when bed depth looks somewhat low. Just when that's going to occur, is like predicting the weather six months from now. But additions in my systems took place a few times a year with small amounts being delivered through a length of PVC pipe to different areas in the aquarium. Then spread out with a small, long handled homemade acrylic rake. Worked well for me.
As for additions to the calcium reactor, the formula you are referring to appears in one of my booklets and pertains to 'sand' with a grain size of about 2 mm. It's there to help hobbyists estimate the number of pounds of live sand when ordering. It does not apply to reactor media because that's a larger grained media. As for brand preferences and ordering, I've mentioned some in your response, and if others have similar interest, please contact me.
Hope this helps,
Bob
