Safeguarding Your System from Meltdown -
Stopping Murphy in His Tracks: Part III

Unpredictable Events, General Tips and Preparing for an Extended Absence

Unpredictable Events:

Spawning Events

A Tridacna maxima spawning. Photo courtesy of Jamie Cross.

Unfortunately, spawning events are very difficult to predict. Sometimes snails will spawn when they sense a particular phase of the moon, a sudden or unusual water condition change (e.g., a large water change), or wide temperature swings. Often snails spawn if they sense a risk to their continued survival. The same is true of other organisms such as sea cucumbers, serpent stars, urchins, anemones, Tridacna clams and potentially, some corals. Sometimes no particular stressor can be determined, and it may be a credit to the aquarist that he has steadfastly maintained a marine organism's health for years, enabling it to grow to an age at which it is capable of reproduction. Spawning is a natural and often fascinating event in an aquarium, but the spawning of large organisms in a small, enclosed system can cause problems. A rapid decrease in the water's dissolved oxygen level can result, as the sudden influx, and subsequent bacterial degradation from the finely divided eggs or sperm, occurs. Snail spawns do not usually contain sufficient biomass to overwhelm the average tank. However, large clams, anemones, corals or the simultaneous spawning of several organisms might be enough to drive dissolved oxygen levels dangerously low, even in a tank with a large skimmer and good water motion. If a large spawn is detected by an aquarist, having a good canister filter on hand that can be charged with some diatomaceous earth for very fine filtration, or activated carbon, can help. The fine-particle filtration will remove the suspended organic particles from the water, minimizing the dissolved oxygen depletion that would otherwise occur as bacteria in the water column consume these nutrients. There may also be miscellaneous organic chemicals released during a spawn, or secondary organic chemicals formed as the materials from the spawn are broken down by bacteria. Activated carbon can help to bind and remove some of these organics in the water. In the event of a major spawning, it may also be advisable to add a working air pump, and several airstones to the tank to help maintain high dissolved oxygen levels. If possible, a large water change should also be performed if the tank's inhabitants begin to show signs of stress such as rapid breathing and listlessness.

image010.jpg JamieCross2.jpg KeddLyttonsmith.jpg
A Sinularia sp. spawning. Photo courtesy of Skip Attix.
An unidentified crab releasing eggs. Photo courtesy of Jamie Cross.
A Plerogyra sinuosa colony spawning. Photo courtesy of Kedd Lyttonsmith.

Rapid Tissue Necrosis (RTN)

Red bugs. Photo courtesy of Ximina's Photography.

High temperatures, heavy loads of suspended particulates, high organic levels and low water motion are several of the environmental factors that are thought to result in an outbreak of RTN, or rapid tissue necrosis. Rapid tissue necrosis can reduce a beautiful, small-polyped stony coral (SPS) dominated reef tank to a glass box full of bleached, tissue-denuded coral skeletons in just a matter of hours or days. While the causes (e.g. bacterial, viral, auto-immune related) will continue to be debated, certain procedures can minimize the probability of this occurrence, and can also slow or stop its progression. I have found that newly acquired Acropora seem to be particularly susceptible to RTN. Thickly branched colonies collected from shallow reef environments with difficult to recreate strong water motion and high light levels, seem to be particularly prone to RTN. The conditions common during shipment, i.e., poor water quality, wild swings in temperature and low dissolved oxygen and water motion, may also increase the risk of an RTN event. When introducing a new colony to a tank I've found it best to pre-dip the coral for 10-15 minutes in a mixture of 5-10 drops of Lugol's iodine solution per liter of tank water, or to simply follow the directions on commercially available iodine-based coral dips. The dip should be performed in an isolated bath with an airstone to provide some water motion. The coral can then be given a quick rinse with tank water to minimize introduction of the dip chemicals into the tank. Ideally, newly acquired specimens should also be quarantined in a separate and isolated system until they are well adapted to tank conditions. Such a quarantine procedure also reduces the chance of introducing any of the coral parasites that are apparently becoming more of a problem in the hobby.

If an RTN event starts to take hold in an established reef tank with no obvious cause other than the addition of a new, stressed coral, then as a last resort the progression of the damage can sometimes be halted by using a whole tank treatment with the antibiotic chloramphenicol as described by Bingman (1997). If all else fails, fragmenting affected corals and saving the upper, healthy branches and moving them to a quarantine tank may allow these specimens to survive.

Caution: As when using any antibiotic, proper procedures should be followed when handling and disposing of chloramphenicol. The use of a dust mask, disposable gloves and safety goggles is recommended. Wash all utensils and surfaces exposed to the drug thoroughly with chlorinated freshwater when done. When disposing of tank water containing chloramphenicol, Bingman (1997) recommends treating it with bleach at the rate of ¼ cup of bleach per gallon. This destroys the antibiotic and any resistant bacteria prior to disposing of the water; it is extremely irresponsible to dump antibiotics into the environment (Bingman, 1997).

Additions of Sand

Adding fresh sand to an established tank can sometimes upset its environmental conditions. Adding new, fine aragonite sand that is not rinsed well can cause sudden clouding of the aquarium. Some corals do not react well to this, and such an upset to the system has been known to start RTN events. Even very well-rinsed, fine aragonite sand will tend to cloud a tank. For this reason, it's best not to add too much sand at once. Stop all water motion, and lower the sand in large cupfuls to the bottom of the aquarium. Also, it has been noted that new, fresh, aragonite sand has a chemically very clean surface. Until the particles are coated with proteins and other substances from the water, the clean surface may promote the precipitation of calcium and alkalinity from the water column, possibly depressing the levels of these important parameters (Holmes-Farley, 2002).

Other Tips for Keeping the Gremlins Away:

Another Pair of Eyes

I highly recommend having an experienced reefkeeping friend occasionally take a look at any new system. Often a fresh point-of-view is helpful and within just a few minutes an experienced aquarist may be able identify many of the potential sources of imminent disaster in the system.

Stinging Critters, Loose Frags, Snails & Urchins

With their stunning green fluorescent highlights, Hydnophora (horn coral) can be really beautiful, but after watching it literally digest an adjacent coral, hobbyists will be certain to keep it away from any valuable corals. The same holds true for other stinging organisms such as anemones. Snails, hermit crabs and particularly, certain sea urchins have a nasty habit of knocking that "Limited Edition" Superman's Best Friend's Nuclear Kryptonite Red Acan Lord with Electric Blue Polyps into your 10-year-old brown frogspawn coral, which may reduce it to a bare white skeleton in a matter of hours. SECURE ALL FRAGS! When acclimating a coral fragment to a tank and slowly moving it to brighter light, consider mounting it with some epoxy or Super Glue™ temporarily to a heavy rock that's difficult for urchins to move. When the coral's final position is determined, pop it off and securely mount it permanently in the rock structure.

This brownish plating Montipora was leaning against this green Hydnophora hard coral for only a few hours. The Hydnophora is extending mesenterial filaments, allowing it to literally digest the Montipora. By the morning, when the filaments have finished their job, there will be a one- to two-inch band of the Montipora's tissue completely gone. Nothing but white skeleton will be left.

Corals on the Sand

Certain corals naturally do well simply placed on the sand. If a sand-moving fish (e.g. a sand sifting goby) or invertebrate (e.g. a pistol shrimp) is added to the tank, carefully monitor the new critter until its habits are understood. In a matter of hours some fish can bury a coral sufficiently to initiate a bacterial or protozoan infection on the coral that may be very difficult to halt.

Sea Apples (Paracucumaria sp. & Pseudocolochirus sp.)

Some species of sea apples can be toxic to fish; either don't get one, or else consider all the fish in the tank as expendable at any time.

Rocks on Tank Bottoms

All structural rock in a reef tank should be placed directly on the tank's bottom, or on some stable support. Do not put down a layer of sand before building the rock structure. Otherwise, as the sand shifts or critters move it about, a rock slide may occur that can damage many corals. If a particularly high stack of heavy rocks are used in the aquascaping of a glass tank, it might be advisable to distribute the weight over a large portion of bottom using inert plastic cushioning material such as Starboard®.

Water Splashing Fish - Electrical Fires

I have had two powder blue tangs (Acanthurus leucosternon) with the annoying habit of splashing water about the tank. The fish rapidly swims the tank's entire length near the surface, and then flicks its tail as it reaches the end, splattering water over the light fixtures, and sometimes out of the tank. One fish splashed so much water that it shorted out an electrical outlet near the tank. With fish that have this tendency (some triggers may also do this to get attention/treats), be certain to take precautions to make ensure saltwater does not make it to the electrical receptacles. Such precautions include using drip loops with electrical cords, and covering outlets with plastic sheeting as necessary. Also consider designing the hood of the tank to minimize the potential for splashes to make their way out of the tank.

Housekeeping Personnel

If new people are cleaning the part of the home where the tank sits, during their first few visits, or anytime they add someone new to their team, it is advisable to instruct them not to use any cleansers near the tank, and in general to keep an eye on the way they clean. Be particularly wary of the use of aerosol sprays of toxic cleaning fluids used in the vicinity of the tank. Is there any chance they might bump a critical piece of equipment? Any chance they might unplug tank equipment when plugging in cleaning tools?

Household Pets Around the Tank

Be certain that any pets that can easily jump do not end up swimming in the tank or sump. Cover the tank or sump if necessary. Installing some plastic egg crate across tank openings might also keep pets out. While it might not significantly affect the tank, the loss of a beloved pet to drowning would be tragic.

Foreign Objects in the Tank - Children

Be certain that there is no chance that a child could drop some object or solution into the tank that might prove to be toxic. If a coin, battery or some such corrodible object were tossed into a tank and not noticed, the result could be a slow (or fast) decline of the tank that might be very difficult to diagnose and rectify. Consider the use of child proof locks on the doors to the area housing the sump, and possibly for any doors that allow access to the top of the tank. For children that are old enough, attempt to educate them on the harm that could come to the animals in the tank if foreign objects ended up in the water. There is also value in educating children to come find you if they think there is a chance something might have gotten into the water by accident, or if they see something wrong in the tank (low water level, fish acting strange, etc.). Keep an eye on neighborhood children that might be visiting and do not know about what could hurt the animals in the tank.

Nothing Fast

Remember the rule that old, salty reefkeepers live by: Any change; any new reefkeeping technique; a new additive or new piece of equipment; a change in lighting, water motion or temperature; or the addition or removal of livestock, rock or sand, should be done slowly. The results of any changes made should be carefully evaluated by observing the reaction of organisms in the tank, and also by monitoring the tank's chemistry using test kits, if appropriate. It's a good idea to jot down observations, test kit readings and any corrections/changes made to the system in a log book for future reference. It will then be easier to say, "Oh, yeah…the problem with 'X' started just about the time I began using 'Y.'" While certainly not proving that 'Y' caused 'X,' the knowledge of the coincidence might help with investigating the problem.

Test Kits

Double-check any unusual results from a test kit. Some values that I've seen quoted by hobbyists are, quite frankly, chemically impossible in a reef tank. Look at the critters in the tank, and if they look okay, chances are that nothing is very far off. Check expiry dates on your test kit's reagents and make sure they are all fresh; often, odd readings can be traced to old reagents. Perform any test at least three times and average the results, this will reduce the impact of imprecise technique.

Dosing Chemicals

Don't go overboard dosing chemicals, as more is not necessarily better. If calculations suggest the addition of a very large amount of some chemical, consider having someone review the calculations or double-check them with an online calculator. Dose over a few hours or days, and observe the organisms' reactions. Remember, taking the chemical out of the water is a lot harder than putting it in.

"Frag" it Out and Spread it Around

I still hear of aquarists who have their main tank crash for some reason and who moan about how this coral or that coral are "irreplaceable." News flash: the corals we grow are capable of nearly infinite vegetative propagation. Take a fragment of EVERY "irreplaceable" coral and give it to an experienced reefkeeping friend. He'll likely share some of his fragments, adding to each other's coral diversity in case something goes wrong. The same goes for those who have multiple tanks. If space is available, put at least one tiny fragment of every "irreplaceable" coral into a completely isolated system, preferably on a different electrical circuit. When the next wave of nasty, chemical-resistant, Acropora eating "monsters from the deep" sweep through the hobby, this isolated tank will contain the new seeds to re-populate the system.

Preparing for an Extended Absence:

1. Tank Sitter: Whenever I go away on vacation I always have someone stay at the house and look over the tanks. I try to have an experienced reefkeeper house sit. So many things can go wrong with a tank (particularly with all my homemade, jury-rigged systems) that I need someone who knows how healthy corals look and who has some ability to troubleshoot the system. I always have my tank sitter visit prior to my trip so I can show him how my system is plumbed. This visit also allows me to point out the system's known weak points so he can make a special effort to check these more frequently. If an experienced reefkeeper cannot be found to tank/house sit, or if a significant other will be doing the watching, it's a good idea to have a local expert standing by who can be called or possibly can rush over to help in an emergency. Try to leave simple fixes and written instructions for how things work. For instance, if something goes wrong with a calcium reactor, it might be best just to inform the tank sitter to close valves A, B, and C (they should be labeled), and to start dumping in "X" mL per day of a two-part calcium and alkalinity solution. Attempting to troubleshoot a complex piece of equipment over the phone with someone who does not already understand how it functions is likely to lead to disaster, or at a minimum, can be quite a strain on the relationship (be certain to hide all the jugs of bleach before you leave!). Frequent trips away is one of the best reasons to join a local reef club, for this is where you will find the best people to look after your tank while you are away.

2. No New Plumbing: Never install any new plumbing or bring a new system on line just before an extended absence. Be careful not to over-tighten bulkheads or plastic fittings. Work all the bugs out of any new system or device many weeks before leaving on a trip.

3. Check Levels Before Leaving: It's a good idea to make sure that parameters such as alkalinity, calcium and magnesium levels are all in their proper ranges before leaving for any length of time. It's also best to perform the testing at least a few days before leaving so that any necessary dosing can be done slowly. The last thing anyone wants to do is to shock the tank with a chemical adjustment (or mistake) just before leaving for an extended period.

4. Backup Circulation Pumps: Have a backup circulation pump standing by. Ideally, the pump should have all the fittings already installed so that installation is as simple as closing a few valves and opening a union fitting or two. Let a tank sitter know where the aquarium tools are located.

5. Have Water Standing By: Have saltwater prepared, aerated and heated, ready to replace at least 20% of the tank's volume in case of some disaster. Time may be critical if something goes wrong in the tank. Trying to talk someone through the proper preparation of saltwater over the phone, or waiting for an RO/DI system to make additional water, is out of the question. If different reservoirs are used for saltwater and RO/DI water, clearly label them so that, in the rush, a water change is not accidentally performed with freshwater.

Have saltwater and freshwater standing by, and clearly labeled, in case they are needed in an emergency. This is particularly important if you are having someone watching your tank while you are away.

6. Extreme Overfeeding: Be sure to explain how much to feed the fish. It's a good idea to label a small bag for each day's worth of food. Sometimes I hide all the extra fish food so that there is no chance of overfeeding while I'm away.

I hope this series has been both informative and enjoyable. Don't put off adding any necessary safeguards. Finally, if something goes wrong and is luckily caught before a disaster occurs, learn from the experience. Be a detective and track down what happened. Whatever is learned and corrected may ultimately save livestock from a future visit from Murphy.

If you have any questions about this article, please visit my author forum on Reef Central.


Bingman, C. 1997. Bacterial Diseases of Corals: Perspectives and "Cures." Talk.

Holmes-Farley, R. 2002. Calcium Carbonate as a Supplement. Advanced Aquarist. I-7.

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Safeguarding Your System from Meltdown - Stopping Murphy in His Tracks: Part III by Greg Hiller -