Here's my advice:
Ammonia and the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com
http://reefkeeping.com/issues/2007-02/rhf/index.php
Ammonia Concentration Guidelines
Because ammonia's toxic effects appear at levels significantly below those that are acutely lethal (0.09 to 3.35 ppm NH3-N or 1.3 to 50 ppm total NH4-N at pH 8.2), and because some organisms in a reef aquarium may be more sensitive than the few organisms that have been carefully studied, it is prudent to err on the side of caution when deciding what concentrations of ammonia to allow in a reef aquarium or related system.
My suggestion is to take some sort of corrective action if the total ammonia rises above 0.1 ppm. This suggestion is also made by Stephen Spotte in his authoritative text,
Captive Seawater Fishes.6 Values in excess of 0.25 ppm total ammonia may require immediate treatment, preferably involving removal of all delicate (ammonia sensitive) organisms from the water containing the ammonia. Some of the possible actions to take are detailed in the following sections listed below.
Treatments for Elevated Ammonia: Hydroxymethanesulfonate
Various types of compounds are used in commercial products to bind ammonia in marine aquaria. One is hydroxymethanesulfonate (HOCH2SO3-). It is a known ammonia binder16 patented for aquarium use by John F. Kuhns17 and sold as
Amquel by Kordon and
ClorAm-X by Reed Mariculture, among others.
Ammonia's reaction with hydroxymethanesulfonate is mechanistically complicated, possibly involving decomposition to formaldehyde and reformation to the product aminomethanesulfonate (shown below).16 The simplified overall reaction is believed to be:
NH3 + HOCH2SO3- --> H2NCH2SO3- + H2O
What ultimately happens to the aminomethanesulfonate in a marine or reef aquarium is not well established, but it does appear to be significantly less toxic than ammonia, and more than likely it is processed by bacteria into other compounds.
Marineland Bio-Safe claims to contain sodium hydroxymethanesulfinic acid (HOCH2SO2-). I do not know if that is a typographical error, or if Marineland really uses this slightly different compound.
Note: products containing hydroxymethanesulfonate hamper the ability to test for ammonia when using certain types of test kits (see above). Presumably, the H2NCH2SO3- formed is still reactive with the Nessler reagents, even though it is not ammonia.
Treatments for Elevated Ammonia: Hydrosulfite and Bisulfite
A second type of compound used in commercial products (such as Seachem Prime) that claim to bind ammonia in marine aquaria is said to contain hydrosulfite (could be either HSO2- or - O2S-SO2-) and bisulfite (HSO3-). These compounds are well known dechlorinating agents, reducing Cl2 to chloride (Cl-), which process is also claimed to occur in these products. It is not apparent to me whether these ingredients actually react with ammonia in some fashion, or whether unstated ingredients in these products perform that function. Seachem chooses to keep the ingredients of their product secret, so aquarists cannot determine for themselves what is taking place, and how suitable it might be. Nevertheless, many aquarists seem to have successfully used products such as these to reduce ammonia's toxicity.
Note: products such as Seachem Prime hamper the ability to
test for ammonia when using certain types of test kits (see above). Presumably, the product formed is still reactive with the Nessler reagents, even though it is not ammonia.
Treatments for Elevated Ammonia: Clinoptilolite
Few filter media are capable of binding ammonia from seawater. The zeolite
clinoptilolite (a sodium aluminosilicate) is capable of binding ammonia from freshwater, but the sodium ions in seawater displace much of the ammonia. In fact, the ammonia binding capacity of clinoptilolite in freshwater can be regenerated by rinsing it with salty water. Consequently, its capacity to bind ammonia in seawater is very low, if any, so it is not a very useful product for marine systems.
Treatments for Elevated Ammonia: Water Changes
Water changes can be a fine way to reduce toxic ammonia levels, especially in a small system such as a quarantine or hospital tank. The effective use of this method, however, demands that the new salt water does not contain significant ammonia. Because many types of artificial seawater do contain
ammonia (see above), this method must be used with caution.
As a rule of thumb, ammonia will usually drop by about the same fraction of water that is changed, so a 30% water change will reduce ammonia by 30%. However, if there is a source of ammonia in the aquarium, it may rapidly rise again. A 30% drop may not be noticed with many test kits. For example, it may be difficult to distinguish 1.2 ppm from 0.84 ppm total NH4-N using many kits, so do not panic if the ammonia level does not appear to drop, but also be realistic about how much you would expect it to drop from a water change on the order of 10-30%. In an ammonia "emergency" much larger water changes may be appropriate. Further information on
water changes is detailed here.
Summary
Ammonia is very toxic to marine fish and other organisms in a reef aquarium. While routine ammonia measurement is not ordinarily required in established reef aquaria, it can be very important when fish are in temporary quarters, such as shipping bags, hospital tanks and quarantine tanks. Most aquarists associate ammonia with new aquarium "cycling," and in that situation it is critically important to wait for ammonia to decrease to very low levels before adding organisms (much more important than waiting for
nitrite to decrease, for example).
Ammonia can also be very important during tank crashes. In all of these situations, I recommend striving to keep ammonia below 0.1 ppm total NH4-N. If the level rises above 0.25 ppm total NH4-N, I suggest taking immediate action, such as using an ammonia binder or performing water changes.
