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So you want to Start a Marine Tank??

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I've noticed a bit of interest in the Marine section of late and thought it might be time to post a 'Sticky' on the subject of 'How to Start a Marine Tank'. That way allot of information will be in the one place, providing a reference to those wanting to expand into the Marine Relm :D

I'd like to take a moment to say that most if not all the information provided within this 'STICKY' has been obtained from A BIG, BOLD, BRASH American reef site that has been around since 1999. I was a Moderator of this site from 2001 to 2004 when the site was fairly young and easy to manage, but today the site regularly sees 50,000-100,000 posts per month, so alot of information to manage, I'm glad I resigned when I did :D. I'm not an active member of this site these days, and mainly use it for research, I rarely post any comments at all, there are plenty of well informed new Moderators to handle that task :D

So enough of the chit chat and lets get started. :D

So, you want to start a Marine tank…

A word of warning: starting a marine tank can cause a serious change in human behavioural patterns - looking dreamy eyed at your tank for hours on end; phoning your loved ones (or anyone!) in the middle of the night to tell them about a new polyp, worm, glowing thingy about 1mm long, ... which you have just discovered; not buying new clothes, furniture etc. because your tank REALLY needs that new light, filter, ROCK, etc.... Oh well, maybe you won't get hooked so badly.

Firstly, get some advice.

Most people’s main source of advice is the Local Fish Store (LFS). Petshops, LFS's, call them what you like, these shops all exist primarily to make money. If they do, they are successful, and the owners can live in comfort (or even grow rich ??). If they don't make money, they go bankrupt. They will always try to sell you the most expensive (often quite useless), items, preferably something which you will have to upgrade later (another sale for them...). And these are the good ones - the bad shops will also sell you incompatible livestock, or diseased fish, or even fish caught with poisons, knowing that they will die after a few days. They can then blame it on you (bad water quality, wrong filter..."you also need this UV steriliser to reduce disease..." and because you are not sure yourself, you inevitably buy more equipment (usually also useless). Get the picture..?? So BUYER BEWARE!

People on Internet discussion groups do not have any financial gain by what they recommend, and are usually impartial, but there is another problem lurking - Pride. "I use skimmer xxx, or pump zzz, this is the best, use it!" "Oh, I've kept 10 types of Angels, and 4 types of Damsels in a 50 gallon tank for the past 5 years, It’s EASY - you can do it too..." or even worse, "Oh, I am very successful with keeping anemones. They are easy to keep, I've had 5 in the last year..."

Advice in books is usually outdated. Details on the animals and plants tend to stay relevant, but "technical" issues such as filters, skimming, lighting, etc. tend to change rapidly, as new equipment and techniques are developed. So, before you decide on anything technical, query what the books say!

Whilst gathering your information, you must THINK. Is it logical, does it agree with what other books say, or with the views of "experts"? You must also get as many recommendations as you can, and then try to decide what is right FOR YOUR PARTICULAR SITUATION. Even some of the most notable "experts" on the net, some even with PhD's, can't agree on "what is right" all the time. They do tend to agree on the basics, though, so if you get some "way off" advice, you should be wary.

Deciding on the TYPE of set-up

Before purchasing ANY equipment, you should decide on what type of environment (or set-up) you want. Some may argue that a fish only tank is easier to keep, as fishes can withstand a greater degree of pollution and water quality fluctuations. A "reef" tank though slightly more difficult, is much more interesting, and gives one a greater sense of achievement and satisfaction. Many people start off with a FO (fish only), only to upgrade to a reef tank later. This invariably results in some equipment having to be replaced, because they did not buy "Reef quality" originally. I would like to suggest that you buy your equipment with a reef tank in mind, even though you may initially plan to keep only fish.

Is "fish only" easier to keep than "Reef"?
The general statement that "a Fish Only system is easier to keep" (or that "inverts are a lot harder to keep") is very misleading, and totally unfair to novice marine aquarists. Let me explain:

Keeping "easy" inverts, such as some species of soft corals, cleaner shrimps, Featherduster worms, etc. are actually easier than keeping fish. They cause much less pollution, and therefore place less of a bio load on the system, which maker filtration a lot less critical. They don't get diseases such as "Ich", and many do not need much feeding either. You do need a minimum amount of light in order to keep corals and other photosynthetic animals. Fortunately the easier "low light" softies, such as brown or green Star Polyps (Pachyclavularia and Briareum spp.), Mushroom corals (Sarcophyton sp.) and Devils Hand or Finger Leather corals can be kept under normal fluorescent lights - though you would need quite a few tubes....

The "difficult" part of keeping a reef tank is when you also want lots of fish in it. This just does not work very well, and is not to be recommended to newbies. Rather start off with a "marginal reef" tank, with lots of live rock, a deep live sand bed substrate (both very important elements of your filtration, as well as being interesting in their own right), some "easy" soft corals, some tube worms, etc. and only a few reef compatible fish.

Do your research first, though. Learn as much as you can about the different filtration methods, compatibility of livestock, food and feeding, and everything else you can pick up... Then, carefully plan your set-up, and GO SLOWLY. In this hobby there is a saying:


If you stock your aquarium before it has cycled properly, you will probably kill your animals. If you stock to rapidly, your tank will have another ammonia/nitrite spike, again probably killing your animals. At best, you will have problem algae, and sick fish. Remember that this is a long-term hobby. It is not uncommon for a tank to only stabilise properly after 6 months. Your corals can outlive you, and even the most common fish can live longer than 20 years, if you do your bit....

Essential Equipment
Equipment does not *have* to be very expensive, but it *usually* ends up costing a great deal more than you originally had in mind.

Tank size and Shape:
Although one could successfully keep very small marine tanks, this is a specialised field, and is not the ideal for a beginner.

Deeper tanks look more natural. They do require more intense lighting, though. They should also only have the same bio-load as a regular depth tank of the same surface area.

A larger tank will be more stable, and forgiving if something goes wrong. A small fish dying in a mature 100-gallon tank would probably not have any effect on the water quality. That same dead fish would most likely cause an ammonia spike, algae bloom and possibly further die off if it was left in a 20 gallon tank.

Your fish will be less stressed in a larger tank (if you don't over-stock), as there is more room to evade aggressors, and to allow each fish to have it's own territory.
It is also easier IMHO to use a surge device (wave-maker) in a larger tank. A 20 litre surge discharged into a 200 litre tank will cause a "tidal wave" to overflow the top. In a 500-litre tank the effect will be less than half, and in a 1000 litre tank it would probably not even cause a ripple.

A pre drilled tank with an "overflow" weir is much better than a conventional tank with a siphon "overflow" to the sump. It allows for a much larger water flow, and is much safer to use, as there is no siphon that can "break" and cause the tank to overflow and/or the sump to run dry.
The disadvantages of a larger tank are mostly financial:

It would cost a lot more to fill the tank, and to do partial water changes

One would require substantially more live rock, and sand, to achieve a decent looking, and properly filtered tank. As live rock and sand are amongst the most expensive purshases, a larger tank would increase the total cost most dramatically.

One would obviously want more corals, etc. This would be added to over time, so work on a constant, long-term drain on the wallet.
Practically, it's more difficult to reach all the "spots" in a large tank when you're doing maintenance and cleaning.
The greater amount of living creatures, and costly live rock, etc. increases the financial risk of losing a major investment if there is a long-term power blackout, the tank cracks, an outbreak of disease, or other disaster. This would cause you to consider the purchase of "back up" equipment, such as a power generator if you want to sleep well at nights.


This will depend on the type of set-up:

"Fish Only" (FO) tank only needs enough light to view the fish comfortably.

If you use "Live Rock" (FOWLR) in your tank, then you should not have less than 2.5-3.0 W/gal (more is better).
"Soft" corals such as star polyps and mushrooms require about 3-4 W/gal (again, more would be better).

Hard corals, clams and anemones need a minimum of 6-8 W/gal, depending on the water depth.

Normal Output (NO) fluorescent lights are mostly used on FO or FOWLR systems, but can be used quite successfully on Reef tanks as well, provided one has the space to accommodate all the tubes. As an example, I have kept a Carpet Anemone in my marginal reef tank for more than 8 months, using 8 x 40W NO tubes on my 55 gal. tank. (I have since upgraded to Metal Halides)

PC (Power Compact) fluorescent lamps are nearly as bright as Metal Halides, and are quite suitable to keep all types of marine animals in all but the deepest tanks. They are quite expensive, though, and not always obtainable.
VHO (Very High Output) fluorescent lamps are "old technology", and are being superseded by the PC's or MH's.

MH (Metal Halide) lamps are the brightest lamps available, and nearly equal the intensity of sunlight. They are probably the most suited type of lighting for deep tanks, and for "Reef" type set-ups with light loving animals such as SPS corals, clams and anemones.
The light "Colour temperature" is also very important. Water "absorbs" the longer wavelength light (the red, orange and yellow colour) at a shallower depth than the shorter wavelength light (green, blue and violet). If one descended from the surface of the ocean, the red light would disappear first, and the last light remaining at depth would be violet.

Sunlight at the water’s surface has a colour temperature of 6 500K. I don't have exact figures, but I believe that the 10 000K light spectrum approximate a depth of around 10m (33') below the surface, and the "bluer" 20 000K spectrum is equivalent of light at a depth of about 20m (66')

Because *most* corals live closer to the surface, 10 000K light would actually be more natural for them than 20 000K light. If one were to set up a "deep water" tank, containing species living at greater depth than that of a "normal" shallow reef, one would be better off to use the 20 000K lamps.


Skimmer - This removes biological waste before it can decompose into ammonia, etc, and thus lightens the load on the bio-filter. Do not skimp on the skimmer - buy the best you can afford. It is perhaps the single most important item you will buy, so rather get one rated at twice your capacity than get one which cannot cope.

In a lightly stocked tank live rock and/or live sand "biological" filtration is all that is required (apart from the skimmer, that is).

In a more heavily populated "fish only" tank, a Wet/Dry trickle filter is probably the best biological filter, though it will lead to a higher nitrate level than live rock filtration.

Canister filters are good "mechanical" filters, but they tend to produce an excess of nitrates in the tank.

Under-gravel filters should be avoided where possible, as they also produce unacceptably high nitrate levels.

A sump – get the largest practical tank, plastic container, etc, which will fit below your tank (or anywhere else that’s convenient). A sump is not really essential, but it does increase the total water volume, and allows one to keep all the ugly equipment (such as heaters, chiller, skimmer, and just about anything else) out of the tank. It is also a great place to make a refugium, and it allows for a more efficient gas exchange due to the tumbling action of the water flowing down into it.

Fresh-water Filters

It is very important to use pure, unpolluted fresh water to replace evaporated water, and to make the salt-water used for partial water exchanges. Using ordinary tap water invariably leads to algae outbreaks.

RO (Reverse Osmoses) filters are the cheapest in the long run, and they remove 95% (or more) of the contaminants from the water.

DI (De Ionisation) filters become exhausted quite soon, and need frequent replacement. This makes this type of filtration quite expensive. DI units typically remove 99% of all contaminants while "fresh".

One can combine the two, first using RO and then DI. This results in the purest water, but IMO is not really necessary.

One could also use a "hand held" water purifier, such as Nitragon, or a household unit such as the Brita filter. These units are actually small DI filters, and work quite well while fresh. Because of their small capacities they are quite expensive, though.
Other equipment:

Heaters: Work on using about 2W/gal to raise the tank temperature 5 degrees F above the room temperature. (Thus for a 55 gal. tank you would need ~ 300W to raise the temperature to ~ 75 F if the surrounding temperature is ~ 60 F). It is better to use two or three smaller heaters than one large one. If a smaller heater fails on, it is unlikely to boil your tank, and if it fails off the other heater can still supply some heat until you (hopefully) discover the problem.

Air pumps: This is not normally needed if you have adequate circulation. It is good to have a standby unit for an emergency, though. I also use mine to aerate freshly made salt water used for partial water exchange.

Thermometer: Get an accurate glass or electronic one - those little "stick on" types are not accurate.

Hydrometer: These are notoriously inaccurate. Get a good glass type, and make sure you know for which temperature it is calibrated.

Pumps – Good water circulation is essential. Buy a good quality return pump (if you’re using a sump), and one or two additional power heads. . A "surge" device or "wavemaker" is a good addition, but is not essential.
Live rock - get about 20% - 40% of the tank's volume of live rock. This is essential for long term water stability (read: low nitrate level).

Sea salt – There are many makes of salt, and not all of them are good. Read the package label, and ask questions on the Net before you buy it. You will not only need salt for the initial makeup, but also for regular partial water changes (about 10%-20% of water volume every 2-4 weeks, depending on stocking level, etc).

"Incidentals" – You will need some test kits, additives such as buffer and calcium, a fish net, some containers to mix your water…

Tank "Cycling"
To be honest, whenever I hear this term, I envisage this large, all glass tank, riding around on a bicycle …..

The term "cycling" is actually a bit of a misnomer, IMHO. In our hobby, it usually refers to a state where the aerobic component of the filtration system has "matured" to such an extent that there are enough aerobic bacteria present in the system to convert the ammonia/um generated by the tank's bio-load into nitrite, and the further conversion of the nitrite into nitrate. In actual fact, this only completes of the first phase of the actual nitrogen cycle.

Until a few years ago, that was as far as the process could go, resulting in a slowly increasing level of nitrate, which could only be reduced by partial water changes. Thanks to the "discovery" of live rock, and later of live sand, the "'cycle" can now be completed by anoxic bacteria living in these substances, further converting the nitrate into inert nitrogen gas.

In hobbyist’s terms, a new system is considered to be "cycling" when there are still detectable levels of ammonia/um and/or nitrite in the water. A system is considered to have "cycled" when these levels drop to zero, and the nitrate level starts to increase.

The important thing to remember is that a tank does not "cycle" only once. The system will reach equilibrium, where there is enough aerobic bacteria living in the filters to maintain an undetectable level of ammonia and nitrite with a given bio-load. Any increase in the bio-load, such as when a new fish is added to the tank, will upset this equilibrium, by "flooding" the system with more ammonia/um than the bacteria can digest. Obviously, with more "food" available for these bacteria, they will multiply (assuming that food was the limiting factor), and in time the system will reach a new equilibrium, able to handle this increased bio-load. This does take time, though, and in the meantime the increased level of ammonia and/or nitrite could be poisoning all the fish.

How to "Cycle" a new tank.

In order to "cycle" a new set-up, one must introduce a source of ammonia/um. In the past, this was usually done by adding some hardy fish (usually Damsels) to the new tank. Although this works very well in a bare tank (with outside filtration), it’s not recommended for two reasons:

It is cruel to keep any fish, no matter how "hardy" in water containing near toxic levels of pollutants.
Damsels are very aggressive, and once the tank has "cycled", they consider the whole tank as their exclusive territory. They will attack, and possibly kill, any new fish being introduced to the tank. To make matters worse, the rock in a typical reef tank makes it hard, if not totally impossible, to catch them when you eventually decide to replace them.

I would start the cycling by initially only adding the sand. Let it settle for 2-3 days, with all the circulation going. Then, add one or two pieces of base quality live rock, and one or two dead prawns or cocktail shrimps (the food type, not a dead one from a LFS - that could be carrying any number of diseases!). At this time, start testing the water for ammonia daily. You should notice an increase in the reading, and after a few days, the reading should stabilise, and then slowly start to drop (this could take 1-2 weeks). At that stage, start testing for nitrite as well, and keep on testing for ammonia. You should now notice an increase in nitrites, and a decrease of ammonia. After another week or so, the ammonia level should be fairly low, and the nitrite level should have reached it's peak.

Once the nitrite level has also started to drop, you can add the rest of the base quality live rock, and once both the ammonia and nitrite levels have become unreadable low, you can then add the good quality live rock (containing many interesting inverts). This could cause another ammonia & nitrite "spike", although it will be much smaller than the first. This is not critical if you’re patient - just let the tank settle for another month or two before adding fish. This should give the macro algae and small critters on the LR time to recover, and to multiply to sustainable levels in the LR, and to migrate into the sand. During this time, you should also add some live sand, and/or some live sand "starter kits" and "reef janitors". Also, don't be concerned with the initial algae growths - it's quite normal to have some diatom, cyano, and hair algae growing as the maturation progresses.

"Cycling" a new system with uncured live rock.

Introduce the LR after the tank's been up about a week, and use it to cycle the tank. Wait at least two months before introducing the first fish.


You don't stress (or kill) any fish, and do not have to add fish that you will have to remove at a later stage.

You don't need to buy fully cured LR. In fact, the cheaper, uncured LR causes a better cycle, and usually have more diverse life forms in/on them.

You can introduce all the rock at once, do your "rockscaping", and have the tank completely set up when introducing the first fish.

You will have amazing growth of whatever comes on the LR - with no fish to eat them, you will get all kinds of macro algae, featherduster worms, soft polyps, even some corals, growing.

You will also enable the "small life", such as copepods and amphipods, to establish and multiply to such an extent that they should survive predation by your fish. Obviously, if you only have 2 or 3 of a specie to start off with, and they're eaten by a fish on the very first day, none will multiply after that.


You will have to wait before you introduce any fish.
Because the initial bio load was smaller, you will have to add your fish at a much slower tempo to avoid causing another ammonia/nitrite spike.

You might have some algae growing on the LR. This is usually not a problem, though, as you start off with a nutrient poor set-up, which can be easily maintained, as there are no fish to feed. Also, the growing macro algae compete for nutrients, thereby restricting the growth of nuisance algae.

Well that's about it for starters, and IMO if you use this guide as a starting point you will set yourself up to having a sucessful marine/Reef tank. Take your time make sure that you understand what you read and 'RESEARCH RESEARCH RESEARCH' :D

Thanks Mick,That is really helpful as i have to start over.Quick question,when i put the new live rock in last week & then everything started new cycle,does that mean everything will be dead in the new rock or just hiding until ammonia drops? Rita

Hi Rita,

That's a very good question :D whislt you should wait a week or to to add the live rock after you put some sand in the tank, if the tank decides to start a new cycle as yours has, you will no doubt lose some of the 'Life' on the rock, if Ammonia levels shoot way high, but the good news is allot of the creatures will survive and in fact thrive, just remember that the 'Live Rock' whilst in transit has been kept moist at times , but certanly not wet and also had to cope with fluctuating temperatures as well, there will be 'Dead' material on the rock even before you get it in your tank. So the answer is 'YES' it will be fine once the tank starts to settle down again.

Hope this helps

Thanks for explaining,I feel lot better as I thought that was it with my tank (kaput).I can quite happily wait as long as it takes now:twirly::D  Rita

As they say, only bad things happen quickly.  May be true, sucks though :p


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