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Cycling is a process that a tank must go through when it is initially set up, in order to establish the necessary bacterial populations that are required to deal with organic compounds that will eventually be present in the tank. These wastes are produced as byproducts of life occurring in the aquarium - fish waste, coral secretions, and uneaten food all break down into their organic components and must be dealt with.

To know that your tank is cycling, you must test for ammonia, nitrite, and nitrate. There must be an initial source of organic material to seed the cycling process. In the past, people originally used small fish to accomplish this, but this is cruel and unecessary. A better method is to use uncured live rock or cocktail shrimp. Once the organic material begins to break down, ammonia will be the first detectable nutrient. Ammonia is deadly to marine life, even in tiny concentrations. Nitrifying bacteria will convert ammonia into nitrite, which is also toxic to marine life, and then further convert it into nitrate, which is much less harmful. Nitrate may be allowed to accumulate at low levels, but it is best to export this through the use of a deep sand bed. Deep sand beds allow populations of anaerobic bacteria to thrive and convert nitrate into nitrogen gas and water. Once ammonia and nitrite consistently read 0 ppm on a reliable test kit, your tank has properly cycled. Expect this process to take anywhere from a few weeks to a month or longer. There are individuals who own tanks that cycled much quicker than this, but it is best to be patient.

It is worthwhile to note that a tank will perform a mini-cycle each and every time its bio load is increased. It is always important to add new livestock to an established tank slowly to make sure that the tank's bacteria population has a chance to adapt.

"How do I know my tank is cycled?"

A tank is considered "cycled" when repeated tests for ammonia and nitrite read 0 ppm. The time it takes to cycle a tank depends on a number of factors, so the only way to know for certain is to test for ammonia and nitrite.

It is important to test for several days to make certain that your tank is cycled. It is possible for ammonia and nitrite to read 0 ppm on one day, and then appear in significant amounts the next day due to increased waste or decomposition in the tank.

"When can I add fish?"

You can add fish or corals once the tank is cycled. It is important to start off slowly, since your tank will experience a mini cycle each time you add more livestock. Test often during this period to make sure you are not exceeding your tank's nutrient export mechanisms. Additionally, many corals require established tanks to do well and you may need to wait longer in order for that to happen. This is also true with clams.

"Should I run my lights while cycling?"

Live rock does not need light in order to stay alive. There are things that may be growing on the rock that need at least a token amount of illumination, like coralline algae or photosynthetic corals. If you decide to run your lighting while cycling your rock, provide vigorous nutrient export to minimize algae growth.

"Should I skim during cycling?"

Yes. Protein skimming will soften the cycle and potentially keep more of the sensitive organisms growing on the rock alive.

"Should I cycle with fish?"

No. Cycling with fish is cruel and unecessary, and when the cycle is done, you may have a fish that you don't want to keep and then have to catch it. Uncured live rock will provide a source of nutrient all on its own. If you wish to induce a cycle, a small piece of cocktail shrimp from your grocery store will do just fine.

"What is cycling with cocktail shrimp?"

Instead of using fish to cycle a tank, many people simply toss a small piece of cocktail or salad shrimp purchased at the grocery store in their tanks until ammonia and nitrite are detectable. The shrimp decomposes, providing a source of food for bacteria.

"Can I add live rock to an existing tank?"

Yes, if you do it correctly. If you're buying live rock online or from any retailer who has to ship it to you, it will always arrive in at least a partially uncured state, even if it was cured to begin with. Adding lots of uncured live rock to a tank will almost certainly cause a large cycle and result in the death of livestock. The rock should be cured in a separate container before adding it to the display tank. This can be something as simple as a big plastic garbage can with a heater, a protein skimmer, and some powerheads.

If you can get cured live rock from a retailer close to you, and then add it to your tank quickly (within the hour), the die off will be minimal and you should be fine. Test your water quality often during this process, just to be safe. Some things like sponges can't be out of water at all without dying, and they can really foul a marine tank if left alone. If you notice sponges on your rock turning black, it is probably best to remove the rock and scrub the dead sponge off of the rock before returning it to the tank.

"Should I buy cured or uncured rock?"

In almost all cases, cured rock will be in at least a partially uncured state when it gets to you, if you order it online. In that regard, uncured rock may be desirable simply for the variety of life that may still be on it. To keep this life on the rock, it becomes necessary to cure it with minimal die-off. Please see "Can I add live rock to an existing tank?" for more information.

"Do I need a protein skimmer?"

The short answer is "No, you don't absolutely, positively need a protein skimmer". There are many people who maintain successful marine aquariums without one. However, protein skimmers provide extra nutrient export and can act as a safety net for your marine aquarium when something goes wrong, like the death of a fish or coral. Untreated, this sudden influx of organic material can overwhelm a tank without a protein skimmer. In almost all cases, people maintaining marine aquariums without protein skimming have experience doing this sort of thing, and it is not generally recommended for those new to the hobby. People who do not use protein skimmers often make use of other types of nutrient export, such as macroalgae refugiums or turf scrubbers.

"What kind of lighting should I buy?"

It really depends on what you intend to keep in the tank. If this is a fish only tank, you only need enough light to make the look nice. If you plan on keeping coral, then it depends on what kind of coral you want to keep. At this point, you need to specifically think about species of corals, since generalizing corals into groups doesn't work very well. Some soft corals are fine under low light, and some do best under intense light, and likewise for stony corals. Having said that, a lot of "SPS corals" require intense light. "LPS corals" and soft corals can usually do quite well under lower amounts of light.

"What kind of corals can I keep (given such and such lighting)"

See the answer to "What kind of lighting should I buy?"

"Should I get a drilled tank or use an overflow box?"

If you're setting up a new tank, a drilled tank is almost always the best way to go. Some overflow boxes are better than others, but they are more prone to losing their siphon and causing a tank to overflow. The overflow boxes which require a pump to maintain a siphon are the ones that seem to have the most problems in this regard.

"Do I need a sump?"

Sumps are incredibly useful devices. They increase the total system water volume, which makes your system's water chemistry more stable, without forcing you to purchase a larger display tank. They give you a place to perform water changes without disrupting your display environment, and give you a place to put things like heaters, carbon, and protein skimmers which look unsightly in a display.

Please read the following articles for more information:

Everything You Always Wanted to Know About Sumps Part 1 Part 2 Part3 by Greg Taylor from ReefKeeping Online Magazine.

"What additives do I need?"

Arguably, none. If you're performing regular water changes, you're probably adding everything your tank needs. In most cases, the only thing that usually needs supplementation in a marine tank is calcium and carbonate. The former is taken up by stony corals, coralline algae, invertebrates (for exoskeletons), and fish (for skeletons), and the latter is consumed in calcification processes, and also converted to bicarbonate when buffering your tank against unwanted downward shifts in pH.

"What good is carbon? Does it do the same thing as protein skimming?"

Activated carbon can remove organics and heavy metals from the water column, so in a way, it provides much of the same function that protein skimming does. For it to be effective, it needs to be changed on a regular basis, such as every few weeks, or once a month. Some people use it all the time, and others use it for a few days a month if they notice their water developing a yellowish tint, which may happen if soft corals are kept in abundance. These corals secrete organic chemicals that, among other things, may cause allopathy in sensitive stony corals. Many people run protein skimmers full time, and supplement with carbon when they feel it is necessary.

"Can I go skimmerless?"

Please see the answer to "Do I need a protein skimmer?".

"What does Kelvin mean for bulb colours?"

The Kelvin (K) rating for bulbs describes the colour of the bulb. All objects that emit light have a blackbody radiation curve associated with them. The higher the K value, the bluer the bulb appears to be. Sunlight at sea level is roughly 5500 K. Light a few feet below sea level is roughly 6500 K, and light reaching the deeper parts of the reef may appear very blue (20,000 K). Actinic bulbs have no true Kelvin rating since they emit their light in a very narrow wavelength range (approximately 420 nanometres).

"How big of a heater do I need?"

The rule of thumb seems to be 2 to 3 watts per gallon of water. It is best to have more than one lower wattage heater than one high wattage heater. If one heater becomes stuck on, the temperature of the tank will not rise quite so fast, and if one heater fails, the other remaining heater can prevent it from falling too quickly. It also depends on what your tank is made of. Acrylic tanks are better insulators than glass ones, so you may need less heat in such cases.

"Glass or acrylic?"

It is up to you. Glass tanks are scratch resistant, relatively cheap, but are heavy to move around and are not as clear as acrylic tanks unless you spend money on starphire glass and get a custom built tank. Acrylic tanks are very clear, but scratch very easily and are better insulators so heat buildup may become a problem. Acrylic is also much easier to drill than glass, if proper care is taken and the drill bits are kept cool. Acrylic tanks may also become the more economical choice for larger tanks, as well.

"Which test kits do I need?"

During the cycling process, you will need good ammonia, nitrite and nitrate test kits. If you plan on keeping stony corals, you will need a calcium test kit and an alkalinity test kit. It is recommended that you purchase a digital pH meter and calibration liquids, since pH test kits are not that accurate. For measuring salinity and specific gravity, it is a good idea to have a refractometer since swingarm specific gravity boxes can be inaccurate as well.

"Why do I have algae? (any kind)"

If you have nutrients entering the tank, and they are not being exported through protein skimming, livestock growth, or water changes, they will probably end up causing algae growth. In particular, if nitrates and phosphates are present in measureable amounts, algae will probably grow in the tank. Lowering nitrate and phosphate levels goes a long way towards reducing the amount of unwanted algae growth in your tank.

One thing anyone who is having algae problems should examine is their source water. If you are using tap water, it is strongly recommended that you invest in a decent Reverse Osmosis (RO) or combined Reverse Osmosis/DeIonization (RO/DI) water purification system. These systems remove almost all of the nuisance nutrients from water and can prevent algae from getting a head start in your tank.

In short, if you can't test for it accurately, don't add it to your tank.

"Do I need a Deep Sand Bed?"

Deep sand beds are a proven way to effectively process nutrient, specifically nitrate. They provide a place for denitrifying bacteria to grow and can go a long way towards preventing outbreaks of nuissance algae.

"Why are bio balls bad?"

Bio balls are exceptionally good at converting ammonia to nitrite and nitrite to nitrate, but their effectiveness stops there. If they are your main source of filtration, nitrates will probably accumulate in your tank, causing algae growth and other problems, like reduced stony coral growth, and eventually (if they get high enough) stress in marine fish. If you have bio balls in your system now, your best option is to slowly remove them over a period of a few weeks in order to give the rest of your system a chance to develop natural mechanisms of nutrient export. Do NOT remove them all at once!

"Should I take bio balls out?"

See the answer to the question "Why are bio balls bad?"

"How do I get rid of bubble algae?"

Bubble algae, or valonia, is a type of nuisance algae that enjoy growth even in tanks with low nutrients. The best course of action is to remove the bubble without breaking it. Breaking the bubble will release spores into the tank and result in more algae growth.

Mithrax (emerald) crabs have been known to eat them, but it seems to be limited to smaller bubbles. If it's not possible to remove the bubble without breaking it, try draining it with a syringe. Insert the needle, siphon out the contents, and then remove the collapsed bubble.

"My phosphates are high! How do I lower them?"

If your phosphates are high, you need to examine the things that you are adding to your tank on a regular basis. Most phosphate problems are caused by overfeeding, poor food choices, or through the use of tap water. Uneaten food will break down and release stored nutrients, including phosphates, into the water column. Flaked food is usually quite high in phosphate and may cause nutrient problems. If you are using tap water, you may want to test it for phosphate contamination. If you have detectable phosphates in your tap water, perhaps it is time to purchase an RO or an RO/DI unit. Please see the question "Why do I have algae? (any kind)" for more information on this.

In addition to these fairly obvious sources of phosphate, you should also examine the brand of activated carbon you may be using in your tank. Some types of carbon contain significant amounts of phosphate due to the manufacturing process. A simple way to tell is to perform a phosphate test on a pure water sample (for a reference point), and then perform another test on a pure water sample with a few grains of carbon in the test tube. If you detect phosphate, you should chose a different carbon brand.

Aside from growing macroalgae and limiting the phosphate entering the tank, two excellent methods for phosphate removal are vigorous protein skimming, and the use of kalkwasser (lime water). Kalkwasser can cause phosphate to precipitate out of solution as calcium phosphate. If kalkwasser is dripped into a protein skimmer, the precipitate can be skimmed right out of the water column, which will prevent it from potentially re-dissolving at a later date.

People have reported some success with the various phosphate sponges on the market, as well. They seem to work best when used to control low levels of phosphate, once the concentration is reduced through other means.

"My water has a yellow tint!"

Yellowish water is often caused by organic compounds secreted by soft corals. If you have many soft corals, or do not use activated carbon or protein skimming, your water may develop a yellow tint due to the buildup of these chemicals. Water changes, activated carbon, and protein skimming will all help restore the clarity of your tank's water.

It should be pointed out that these chemicals are often times toxic to stony corals like Acropora. Unless they are removed, stony corals may not do well in your tank. This effect is known as allopathy, and can be quite problematic in tanks that house a mixture of soft and stony corals.

"What salinity should I have?"

The best salinity is a stable one. Obviously, you should try to keep your salinity close to what you would encounter out on a real reef, but salinity fluctuates around the world. Most people advocate a salinity of 34-36 ppt, or a specific gravity of 1.024-1.027. Many people run "fish only" displays at lower values to reduce the likelyhood that fish will be affected by parasites. Stability is the most important aspect of a tank's salinity. Constantly changing salinity is stressful to marine inhabitants.

"What temperature is best? (uh oh)"

"Aquarium Corals" by Eric Borneman (page 349) cites reef temperatures as having a minimum average across all tested reefs of 70F, a maximum average across all tested reefs of 86F, and an average temperature across all tested reefs of 82F. In light of this, it is recommended that you maintain your aquarium inside of this range. RTN (rapid tissue necrosis) in stony corals seems to be linked to higher temperatures. Most people prefer to run their tanks between 79F and 82F.

"What cleanup crew should I have?"

It depends on your tank. Most people recommend a general mix of various types of snails and hermit crabs, with other invertebrates and algae eaters thrown into the mix as desired. Sea urchins and sea cucumbers are popular as well, although these invertebrates are quite sensitive. Some species of cucumbers can be quite toxic to marine tanks if they die, and urchins have been known to graze on coralline algae and knock over live rock if it is not secured properly.

If you are adding more members to you cleanup crew, it may be helpful to determine what problem areas exist in your tank and add creatures that specifically target those areas. Some snails eat film algae, while others prefer to sift through sand looking for detrius, for instance. Bristleworms may be added to deal with detrius in the sand as well. Likewise, urchins and larger snails, as well as hermit crabs, may be added to a tank to graze on longer hair algae.

"Can I keep these fish?"

That depends on what you already have in the tank. Some species of fish (like tangs) need a lot of swimming room and don't get along that well with others of the same or similar species. Some fish are not reef safe and may eat corals, nip at clams, or eat invertebrates and should be kept in fish only or predator tanks. Other types of fish have very specific diets and are hard to keep in tanks that are not established, like the beautiful but fragile mandarin goby.

"How do I get rid of Ich?"

Ich is stress-related. Healthy fish do not normally develop Ich, so if a fish shows signs of it, it is best to determine what caused the fish to become stressed in the first place. Examine water quality, overcrowding, or aggressive behavior from other tank inhabitants.

Treatments for Ich depend on the situation. Copper-based medications generally work best, but are not suitable for reef aquariums, since copper is very toxic to invertebrate life. If you can't move the fish to a quarantine tank for copper-based treatment, foods soaked in garlic extract have been reported (anecdotally) to be effective. A freshwater dip may also cause parasites to drop off of the fish.

"How do I make coralline algae grow?"

The recipe for success regarding coralline is to have calcium levels of roughly 400 ppm, alkalinity levels between 3 and 4 meq/L (8.4 dKH and 11.2 dKH), extremely low phosphate (undetectable on a test kit), and good current flow. Intense light is not required for coralline, but your lighting regimen may dictate the colour of coralline that will thrive in your tank. The darker red and deep purple types of coralline seem to grow best under low light, and the lighter purple to white varieties seem to grow best under brighter lighting.

"How often should I feed my fish?"

Ideally, fish should be able to eat whenever they are hungry. For herbivorous grazers like Tangs, that usually means that some type of edible algae be present for them all day long. This could be cultivated macroalgae in the tank, or introduced algae like Nori (sushi wrap seaweed) on a clip in the tank where it can be grazed on. Fish that prefer meaty foods will probably need to be fed at least once a day in small amounts to prevent overfeeding at once.

It depends on the fish, and if you aren't sure, ask. Lionfish, for instance, are voracious predators that only need to be fed once a week (and not on freshwater goldfish!), and mandarin dragonets need a special diet of live amphipods or copepods growing in an established tank.

"Can I use tap or well water in my tank?"

You can, and people do, but you may be asking for trouble down the road. Water is corrosive and in traveling through the pipes to your house it may pick up iron and copper from the plumbing. Many water suppliers add phosphates to make the water less corrosive. This can create nuisance algae and inhibit coral growth. Well water is often free of phosphates but may contain high levels of nitrates. Natural metal levels in the water accumulate as evaporation and the resulting water top-off increase the concentration. Any reef enthusiast is well served by purchasing an RO/DI unit to improve water quality here is a link to questions on that subject- Ro/Di-FAQ

"Can I use a tap water purifier to supply water for my tank?"

If you have a nano tank it may be OK. The big problem with tap filter is the limited capacity of the filter and the subsequent cost to replace it. A tap water filter will only produce 50-100 gallons of water before it is exhausted. An RO/DI can produce 2000-3000 gallons before you need to replace the DI cartridge. A tap water filter replacement is around $20 while the DI canister is around $25. That means you pay about 40 times as much per gallon for tap water filtered water compared to RO/DI. At that rate it doesn’t take long to justify the extra cost of the RO/DI system.

"What’s the difference between alkalinity and pH?"

pH is the scale that measures how acidic or basic a substance is. It has the scale of 0-14 with 7 being neutral. Values less than 7 indicate an acid while those above indicate a base. Lemon juice (citric acid) is an acid with a pH of around 2.3. Borax (sodium borate) is a base with a pH of around 9.2. In a reef aquarium you want to maintain the pH in the mildly basic range of 8.0-8.4. Alkalinity is the ability of water to resist the pH being lowered by acids. Acids in your tank come from the respiration of carbon dioxide and organic acids produced as a waste product of metabolism. Alkalinity neutralizes these acids. Alkalinity is generally considered to be the amount of bicarbonate and carbonate in your tank water. Borate is also sometimes included as it is used in some salt mixes to boost alkalinity. A tank with sufficient alkalinity will maintain a stable pH. Here are two articles on pH, alkalinity and calcium, whose level is also influence by alkalinity levels.

Alkalinity Article #1 by Randy Holmes-Farley from Advanced Aquarist's Online Magazine.

Alkalinity Article #2 by Randy Holmes-Farley from Advanced Aquarist's Online Magazine.

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