Summary and thoughts
What I see emerging here is a recurring theme of limiting nutrients, which is not new to the hobby. We seem to all be in agreement with this.
In studying biology as a hobbyist, student and professional there is a recurring theme that mostly repeats what we have observed. 1) Nutrients are limiting. Also, that 2) life depends on limiting factors and these occur in an order of priority, with major and minor factors.
An example of this would be something like this: If we are talking about growing algae, then light (sunlight or artificial)), co2, nitrogen (nitrate or ammonium), phosphorous (phosphate) and potassium would be among major limiting factors. Then- magnesium, manganese, sulphur, iodine (iodide), silicon, etc. would be among minor limiting factors. These are sometimes referred to as 'nutrients' and 'trace elements'. A limit in any one of the major factors causes a limited maximum metabolic rate to be achieved regardless of the amount of the other factors. The minor factors will have an effect if limited but not as pronounced in either time or degree.
We have focused on nitrate reduction using sand beds, with or without plenums. Regardless of the amount of other factors present in our tanks (including phosphorous), if available nitrogen is limited (nitrate in particular, assuming our tanks are cycled of course) we get better results. 3)Assuming that our tanks are in otherwise 'good condition', Nitrate in particular appears to be detrimental to the health of corals. It is for that reason that we are here discussing this, true?
I set up my first saltwater tank in 1973. I initially had more failure than success, but it did 2 things for me. 1) taught me a lot through experimentation and observation; and 2) instilled in me a desire to learn more, that has lasted to this day. I have tried the big three methods of keeping aquariums, both salt and fresh water. These are
1-high tech,
2-low tech and
3-no tech.
Below I will summarize my findings for saltwater.
What works:
-Limited feeding (balance requirements of specimens and the system)
-testing your water using a good commercial test kit (more if you're a newbie, less often with experience)
-protein skimming (I like paddle wheel designs, I think large high powered downdrafts are inefficient from a power perspective)
-partial water changes (I prefer about 5% of actual volume per week)
-activated carbon (suggested reading-http://www.hallman.org/filter/gac.html)
-low bio-load to volume ratio (limit the addition of fish especially)
-refugiums (more balance/stability/diversity)
-algae (prefer chaetomorpha in a refugium)
-adding calcium (suggested reading-http://www.reefscapes.net/articles/breefcase/kalkwasser.html)
*the above step combines calcium with carbon 'boosting'*
-adding magnesium, iodine, strontium for coral growth
-Other than the reef itself, the best investment you can possibly make is a backup power supply. The preferred system will have an 'automatic switch-over' capability, because when you loose power Murphy will be at fault, and you will not be home. It does not have to run everything, but the pumps are a must!
I have used nitrate reactors with great success, both commercial designs and self made. If you understand them, they are no more difficult to maintain than any other component in a marine aquarium (reef or otherwise). To be successful you must 'feed' them. This involves the addition of organic carbon, whether in the form of alcohols, sugars, or in my case calcium acetate (see above calcium addition), or one type that uses sulphur (which I have not tried) . They operate as an anaerobic digester. This means there is VERY little or no oxygen present. Anything you may have learned about how 'aerobic' or conventional aquariums work, does not apply here. In fact, they are exact opposites. Instead of an oxidizing environment, they use a reducing environment to eliminate the nitrate. If you don't understand them, I suggest you speak to someone that does, or read up on them before trying one. I personally prefer designs that do not require me to tear apart the thing for maintenence. This, as with so many other things, defeats the purpose of having the aquarium. That is: TO ENJOY IT.
Note:
Sugar/vodka/etc. does not contain ATP. These 'foodsources' may be used by organisms to convert to ATP, or adenosine triphosphate as it is also known. ATP is the 'universal' energy molecule of life on earth. During respiration ATP gives up phosphate to form ADP (diphosphate), and possibly AMP (monophosphate) under the right conditions. This molecule provides energy for the organism at the cellular level.
Note:
Constructing a plenum is simple. It requires eggcrate, small diameter pvc (I used 1/2 inch), pull ties (the kind without metal in them) and some plastic window screen material. You simply cut eggcrate to dimensions of tank bottom less an inch or so for gravel around the edges. use pull ties to secure pvc to eggcrate bottom (lengthwise). Cover top and sides of eggcrate with window screen (you may use small pull ties to secure the screen to eggcrate, and 'wrap' the screen around the edges and tuck underneath the plenum). Place assembled plenum on bottom of tank. Cover with aragonite based (crushed coral rock) gravel. The suggested gravel size is 1-2 mm, 3-4 inches deep. Suggested reading (basic description)-http://www.aquariumpros.com/articles/biofiltertypes.shtml
I suggest the plenum go in a separate tank/refugium which can be isolated from the rest of the system if needed.
Not tried/observations:
-bare bottom tanks, THEY ARE UGLY...IMO.
-electrical denitrator, an expensive gadget with some merit but was impractical, not tried
-personally do not care for/see the need for ozone
-ORP is a good indicator of overall system health, but is NOT AN INDICATOR OF A PARTICULAR PARAMETER (including oxygen), other than the availability of electrons in the system.
-iron oxide for phosphate removal has merit, with added advantage of being easily removed if placed within a mesh bag. Works better in a flow through application.
-reefkeeping requires work, by yourself or someone else
-any effort reducing work required, enhances enjoyment
-KISS principle is essential for long term success (see above)
-The 'low tech' approach has consistently yielded best results
-I design and build most of my system components, excluding the glass box, because I enjoy that too. Also, I get to try things the way I think best, or do things no one else has. This BRINGS ME JOY also.
-Use a GFCI type circuit breaker on anything connected to your tank. It may save your life.
-Use an inert type metal (titanium) grounding probe in your tank(s). See above. PS-clean it regularly
-Do not be afraid to experiement, within reason.
-Minimize the potential harm to the life forms under your care.