Many questions exist on the best way to set up a FO Tank, given the fact that more emphasis today is placed on a Reef system. Much can be learned from advances made in Marine Aquariology from the Reef sector. Now the main thrust of Reef Aquaria is the reduction or elimination of nitrate, in order to sustain invertebrate life. It has been shown that fish have a far wider tolerance for nitrate, as long as its accumulation is built up slowly. Nitrate is still, by and large, NOT natural in the ocean, and in no-way can we assume that it does not pose some threat to our fish's health and longevity.
When setting up a FO tank, considerations for nitrate control should be incorporated into its design and execution, plus the benefits of starting the bacteria cultures for nitrification. The advantages of utilizing Reef type set-ups is two-fold, first, fish are NOT necessary to 'cycle' a tank, and secondly, the establishment of dentrification can enhance and increase the biological capacity of your aquarium. That means more fish per inch per gallon ratios, that so much is talked about.
OK, how are we going to do this? Most new or fledgling SW aquarists will go to a LFS for advice. We all just about do this. Some of us have been more fortunate in that we started with FW and have experienced what it takes to keep fish in general. Some of us have actually been inspired to read and study, before we venture forth. Just let me add that, for the most part, what's readily available from the 'experts', books, and LFS's is, for the most part wholly behind the times!
Most of the advances in modern SW aquariology has not even reached the publishing stage, and we have to rely more on the new internet sites, to find out. At this point I will not make specific recommendations, as opinions vary widely, on much of what's available, book wise. I will say that what's been written is of great benefit in understanding the principles of marine aquariology, but lacks the knowledge and experience of the more advanced research and discoveries.
I do suggest good basic books, to research fundamentals, but exploration of the internet, especially in areas covering Reef Aquaria, will prove more beneficial until one has enough experience 'under one's belt'.
This is definitely a perplexing and frustrating area. We all do want that 'beauiful' aquarium we have seen, either in pictures, your LFS or a friends place. Many people go to public aquariums and are inspired by what they see. Just let it be known that this is not as much a 'hobby' as a scientific undertakng, requiring a great deal of study and patience. You are going into biological processes necessary for sustaining life in a captive environment, and is just not as 'easy' as it appears.
The requirements for SW aquaria has probably been inherited from FW, which is truly not the same. SW environments are unique and cannot be extrapolated from FW specifications or parameters. About the only thing the two have in common is the primary need for an enclosure, aeration, biological filteration, and the liquid (water) from which they both start from.
Comparisons do have to be made, because much that is recommended for SW really came from FW. First off we need a substrate. This substrate material is critical for SW, in that it serves many purposes. Even though recommendations made by some 'experts' to the contrary, calcerous based substrate materials serve the needs of SW aquarias in the fact that, in the long run, by and large, these materials have added to the stability and longevity of the tank and its inhabitants.
The most popular substrate materials today are crushed coral and aragonite. Essentially they are both the same, only differing in the crystalline form of the minerals from which they are composed, calcium carbonate. Crushed coral is just that, coral skeltons reduced to sand form. Its crystalline structure is more dense, hence its more 'brittle' and is consequently harder to process. Its grain size tends to be larger, and because of its impact on coral reefs, its use has met disfavor from more conservation minded aquarists. The preferred material is called aragonite, originally used for building bricks for walls and fortifications, in medieval times, in the Aragon region of northern Spain, hence the name aragonite. Its now been recognized as sand deposits in many parts of the world, and has many applications outside the SW aquarium trade. It is also available in places that sell buiding materials, under different names.
HomeDepot� stores sell it under the name of Southdown� Tropical Playsand� used for sandboxes. Unfortunately it has limited distribution and availability, so individual inquiries have to be made. Use some caution, as other people make playsand, made from silica, rather then calcium carbonate, and although (silica) is being used by some more advanced aquarists, it has no buffering capacity, and not recommended in larger aquarias, under long term conditions. Many sands available from the building trades sources contain many impurities which can turn out to be very harmfull in the establishment of a SW aquarium. When in doubt as to the purity of any and all materials, its better to be "dollar wise then penny foolish"!
Aragonites prime benefits is that its available in differing grain sizes, is cheaper to produce, and because its environmentally 'friendly', has caused crushed coral use to be in disfavor for the conscientious SW aquarist. Substrate construction is of prime importance, just as much for a Reef, as FO. The basic difference is that in a Reef, your substrate is innoculated with LiveSand, rich in benthic life forms, that promote denitrification. Unfortunately, many fish also feed on LiveSand creatures, so their inclusion is only considered for FO set-ups.
The recommendations for substrate depths are different, depending on the type and characteristic of the fish one is going to have. For heavy or messy eaters, a shallower 2 to 3 inch substrate of material 2 - 3mm in size, so that water circulation will more easily penetrate, to avoid anoxic conditions, and the possibility of the formation of hydrogen sulfide producing bacteria.
If one desires sand stirrers or sifters, such as gobies, or jawfish, or burrowing fish, such as wrasses, then having a finer, deeper substrate will be highly beneficial and they in turn will prevent anoxic conditions, so necessary to avoid in a FO system, without a DSB.
The calculations for determining substrate depth is that 10 lbs. of aragonite will give you a one inch depth for every square foot of your tanks bottom. Using a 100 gal standard aquarium, which has 8 sq ft of area, a 2 inch substrate requires 2 x 8 x 10 = 160 lbs of aragonite. For a 4 inch sand bed, you will need 320 lbs. of aragonite.
Now for the 'coup de gras' of 'cycling'. No more, the torturing and agonizing subjugation of fish to ammonia and nitrite! With the proliferation of Reef aquarias, a new 'product' has become widely available, Live or Cultured Rock. LiveRock is rubble, found in the ocean, adjacent to coral reefs, and has come as a result of storms and strong ocean currents. As informed sources have shown, corals reefs are not harmed in any way by the harvesting of LiveRock. Some prefer 'cultured rock' being produced by some people in Florida, where 'dead' rock is made 'live'. This is just as well and good, if that's more preferable to the aquarist.
This is the basis of your new FO tank, a shallower sand bed with LiveRock. Recommendations on the amount of LiveRock varies with taste as well as practical considerations. The more you have, the greater benefits you will derive from denitrification processs. Pounds per gallon designations are not as critical as in Reef systems. Most aquarists in FO systems do not use as much as Reefers do. One pound per gallon is generally sufficient.
Now for the final touches. Recommendations for skimming is more often then not, being made, and for the new aquarist, its not a bad idea. Make sure that the skimmers capacity is at least twice what your tanks size is. More is still better, as aquarists have more problems because, even though their skimmers designations are for a tank the size its being applied to, in most cases, its inadequate in real life situations, especially with the heavier bio-loads that a FO tank presents.
The same can be said about carbon filtration, in keeping water 'clear' and sparkly. Both skimming and carbon filtration are optional, in this authors opinion. However, until one has gained sufficient experience, both can be a good idea for FO applications.
The only additional requirements for a FO tank is a high level of water movement, especially for gas exchange and oxygenation. My recommendation is 20 times turnover rate (gross) for gallonage designations. For a 100 gallon tank, thats 2,000 gph of water turnover. This can come in many forms. Overflow systems, with sumps, with or without bio-material, skimming, carbon filtration, and water return, or magnetically driven pumps pushing into canister filters, with bio material or for combination mechanical/biological/chemical filtration. Submerged power heads can be used to supplement additional water movement. Other devices for the establishment of biological filtration include hang-on filters with 'bio-wheels'. In all cases, the principles are the same, highly oygenated water is passed through material where bacteria can form and process toxic nitrogenous wastes of fish, into less toxic forms. The more emphasis is placed on having a high level of water movement in the tank, resulting in greater denitrification, because of the sand bed construction and the use of LiveRock, the less device intensive the tank needs to be. Most aquarists simply do not trust the application of denitrifying principles, and still use wet/dry's or canisters, or even UGF's. That is the aquarists choice, and whatever he or she is comfortable with, should be the way one goes. Not all of us are as adventurous as to go, where few others have gone. All these systems work with varying degrees of success, once an understanding of whats being accomplished, and desired. Its really not that complicated, water movement, sand bed, liverock, temperature control and lighting. The adjuncts are skimming, mechanical/biological and chemical filtration.
My whole purpose in this discussion is really, the elimination of the old, archiac, and cruel practice of subjecting fish to the tortures of biological cycling. Today, its totally unnecessary. The only real problem is that, one does have to wait 6 to 8 weeks, and remain 'fishless' until cycling has been completed. A very small price to pay, considering the benefits and joy of having a beautiful set-up!
Don't forget you also need an array of test equipment, initially to monitor levels of ammonia, nitrite and nitrate. A floating type hydrometer is important, as well as an accurate method for checking pH, the alkalinity of your SW. You tank is not cycled until ammonia and nitrite levels are ZERO, and nitrate levels is all you have. Its best to keep nitrate levels below 20 ppm, which is easily accomplished by frequent water changes. I recommend 1/3 changes every 3 to 4 weeks, depending on your nitrate measurements. Fish are known to withstand nitate levels exceeding 200 ppm, but only when there as been a slow acclimation process. Problems arise mainly when a new fish is introduced, formerly kept in a much lower level of nitrate. Of more critical importance is the maintenance of a constant pH. The ideal is 8.3, the same as the ocean's pH. Fish's tolerance for abrupt pH changes is extremely narrow.
As has been repeated in my many columns, Quarantine is highly recommended for all new purchases. Although in a FO set-up, treatment is easier, there is still the danger of damaging biological filtration, and the resultant process of 're-cycling', and ammonia, can easily wipe out what had been so hard to achieve. Its just that much easier to treat one fish in a quarantine tank, then a tank full of fish. An additional word about water test kits and testing procedures. With the many and various brand name test kits on the market, both at your LFS and Mail Order, it can get quite confusing as which to get. Recommendations widely differ, and price differentials also. Naturally, your LFS wants to sell you what he has, and of course, his are the 'best'. When I first started, there were few to choose from and you took your LFS's word. Today its far different, as there are close to a dozen different manufacturers, each making the same claim. My best suggestion is to get at least three different manuf's. products, and compare them with each other and some 'standard' such as distilled water. You will note that most kits work in both FW and SW. That is a fallacy, in this authors opinion, as SW constituents confound results, and no standards exist for SW. All standard solutions are FW! Just be aware of this and be critical of test results, especially in the face of conflicting evidence. Many a time I have read that an aquarist's water measures 'good' whatever that is, and yet his fish are showing signs of great toxicity.
That's why its important to have several different test kits for the same measure, especially when first starting out, and do testing on a regular basis.
Once you have reached a level of confidence, and can maintain consistent water conditions, testing becomes less important. Your animals will tell you more about your water conditions. Still, its a good idea to get into the habit of regular water testing and observation, which in many cases, can stave off some impending problem. I recommend testing water for nitrate and pH, once a week, once cycling has been completed. When employing LiveRock for cycling, water changes are not necessary until cycling has been completed, which is ZERO ammonia and nitrite, and only measureable nitrate. If nitrate levels are unsually high (80 to 100ppm) then do several consecutive water changes, to bring it down.
Once water parameters are stable, and nitrate levels below 20ppm, then its safe to introduce fish. My caveat still holds true, set up a Quarantine tank, a miniature of your main tank, and observe fish for 3 weeks before introduction. This is far more critical if your going to mix fish with invertebrates, but nevertheless, should be a hard and fast rule!
My recommendations for water parameters are: Temperature set at 79�F on your heater (minimum). Maximum allowable temp. for most species 86�F, although measures should be employed to keep temperature as stable as possible. Salinity as measured by a floating hydrometer, temperature compensated, 1.018 to 1.021. I do keep my salinity on the low side, as this seems to benefit my fish, and does make life harder for any parasites that survive after quarantine. Ideal pH is 8.3, but does fluctuate between 8.0 and 8.4. I do not allow my pH to stay at 8.0 without adding buffering in the form of Arm and Hammer�Baking Soda, one heaping tsp. for every twenty gallons of NET water capacity, premixed in one gallon containers, and then added slowly to my aquarium's water. I wait 24 hours before re-checking pH, and re-dose if necessary, until I reach 8.4, in 24 hour intervals.
Nitrate levels do build up over time, especially in a heavily stocked tank, no matter how much denitrification you have. I recommend a water change once nitrate levels reach close to 100 ppm. My water change routine is normally about 33 gals for my 110 gal tank, monthly, which is approx 1/3 of your stated tanks capacity. Just remember that your tank's actual capacity is probably only 70% of its advertised size! This is very important when your considering stocking capacities or treatment or correction dosing.
Once cycling as been completed, its not really necessary to check for ammonia or nitrite, as you can get 'false' readings from some test kits, plus de-chlorinators, especially chloramine removers can show false ammonia levels. Your tank's inhabitants are clearly the best indicators of water quality. And as always: "IF IT AIN'T BROKE, DON'T FIX IT!"