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  • Setting up a N.Z. local marine tank.

    Setting up a N.Z. local marine tank

    Author: Mark Paterson

    New Zealand coastal waters have a unique and diverse range of flora and fauna present as they cover temperature ranges from sub-tropical to sub-Antarctic with major current systems impacting on its shores. Its waters are thought to contain over 15,000 known species and scientists believe there may be as many as 65,000 marine species present, with many of these species not found anywhere else in the world due to the country's isolation.

    There are some very different kinds of marine environments, rocky shore, mud flat, estuaries, varying tidal environments, but most people's introduction to our local marine life is through the rock pools at the local beach, these pools can contain a wide range of animals and plants that are exposed to a wide range of fluctuations. Exposure to summer sun can create high water temperatures which in turn will lead to evaporation so the salinity can get very high, or in turn rain can drop the salinity rapidly. The sun can also increase the photosynthesis of algae to generate oxygen, which can raise the pH levels so your average rock pool inhabitant can survive a wide variety of conditions.

    These pools are generally flushed with new water twice a day which keeps them functioning whereas in the home aquaria doing this can be time consuming and expensive if using artificial salt water. So to compensate for this some care is needed to set up an aquarium that won’t end up a smelly soup after a few months of running.

    To create a sustainable closed system the first step is to have lots of patience, a cold water marine system takes longer to cycle than a tropical marine one and both take longer to cycle than freshwater tanks, the full cycling process can take anywhere from 3 months up to a year to attain a mature system. Most aspects of saltwater aquarium keeping are universal. Regardless of whether the ultimate goal is a fish-only tank or a reef style tank, installation of the equipment requires the same steps and water quality is paramount. Similarly, all saltwater tanks require the active participation of beneficial micro-organisms therefore, in the early stages of the tank’s development; the procedure is focused on getting these unseen helpers established.

    First you need to understand the nitrogen cycle and how the bacteria in the live rock actually break down the wastes excreted by the various living organisms in the tank.



    Basically all fish and invertebrates excrete ammonia as a waste product; ammonia is extremely toxic to them. There is a group of beneficial bacteria that convert ammonia into nitrites which are also toxic; a second group of microbes convert nitrites into nitrates, which are not nearly as toxic. Accumulated nitrates should ideally be kept below 10 ppm, but fish may show no ill-effects with slightly higher levels. These two groups of bacteria need to be present and established in sufficient numbers prior to adding your fish and other animals. Ammonia levels will raise followed by a rise in nitrite levels as ammonia begins to decline. Then, as nitrite levels begin to decline, you will more than likely see a very slow rise in nitrates. The appearance of nitrates is a good sign that your various bacteria are making all the necessary conversions, however, some tanks with a significant amount of live rock, live sand, macro algae, and are regularly maintained with water changes may never see nitrates accumulate.


    There are several methods that can be used to cycle a tank, however, the basics are both cycling with or without fish, if you don’t have access to fresh salt water please don’t cycle with fish as they cannot generally tolerate high ammonia levels and water changes required can be expensive if using an artificial salt mix.


    Cycling With Fish

    Using fish to cycle a new saltwater aquarium is one way of preparing the new tank for life but nitrite and ammonia can reach toxic levels during the process. There are only a few fish that live naturally in this environment, Triple fins found in pools higher in the tidal zone, Parore, Rockfish and spotties. Frequent water changes will help to keep the water parameters stable for the inhabitants.


    Cycling Without Fish

    Ammonia is needed for the cycling process to succeed so it can be produced in several ways. From dead decomposing matter, a piece of mussel or a fish to using unscented ammonia that doesn't contain any additives, the goal is to maintain a level of 5 ppm of ammonia in the tank which is usually achieved by adding 3 to 5 drops of ammonia to every 20 litres of water on a daily basis.  Continue adding the ammonia and testing the water until it shows a nitrite reading once this shows reduce to 2 to 3 drops per 20 litres until both the nitrite and ammonia tests reach 0 ppm. Once you have this then a large water change can be done, watch temperature as too large a variance can stress the bacteria; add some activated carbon to help remove any unwanted additives that may have been in the ammonia.


    Allowing the tank to cycle is crucial, it's the process that creates a chemical balance that can sustain plant and fish life, prior to cycling make sure your tank is up and running and your equipment is properly functioning. Circulation and a stable temperature are essential factors for the health of your livestock long-term as well as at the beginning when bacteria levels are establishing. It is good to run your tank lighting on for several hours each day during cycling as it will help set the balance for when the tank is stocked.  For any cycling method you want to use a good quality salt mix or natural salt water (NSW). While cycling (regardless of the exact method), you will need to maintain your salinity around 1.027 and your temperature between 18C and 20C. If you have access to fresh clean natural salt water (NSW) you can set a tank up from scratch by doing 2 x 25% or 1 x 50% water changes weekly with a few hardy fish to help cycle the tank (Parore, Spotty, Rockfish)



    Clean natural salt water can be collected locally in many parts of New Zealand; you just need to ensure it is clean. Collecting about half an hour before high tide is best but not after any recent rain as this can include contaminants from land runoff. Near river mouths or areas where there is a lot of boat activity should be avoided as well for the same reasons. Collected water can be stored indefinitely in sealed containers away from any light sources.

    The task of collecting water can be made easier by using a 12V pump that plugs into the vehicles cigarette lighter and then pumping into large resealable, food grade plastic containers.





    The two main essentials for good water filtration are live rock and a good quality protein skimmer.


    Coral Rock

    You will need some clean coral rock as this is more porous than rocks from the sea and makes a good home for the beneficial bacteria and pods that will help maintain your system to live in.

    You can use live rock from a tropical marine tank but some of the bacteria etc. may die off in the transition.

    Coral rock is often purchased dry, and the bacteria are dead, or have formed spores. This live rock has to be cured which means left in water for a period of 6 weeks or longer, until all the various types of bacteria have established themselves and the rock can be used to provide filtration in a tank. Rock from the sea with encrusting inverts or plants may be added once cycle is completed, if it is added too early the life on it will die and add to an ammonia spike.


    How do you know when the curing process is complete?

    As the rock cures, decaying organisms will produce ammonia, which will be converted to nitrite by beneficial bacteria. As curing proceeds, additional bacteria will oxidise the nitrite to nitrate. Therefore, simply test the water for nitrite periodically and keep track of the results. You will see an initial rise, a peak, and then a sharp decline to zero. At that point, the curing process has run its course, usually after about two weeks. During the cycling process you can test the water every few days until you have the ammonia levels controlled. Once the nitrate levels reach 25.0+ the cycle is complete and you can safely add fish to your saltwater aquarium.



    The tank can be set up with substrate or no substrate (BB, bare bottomed), having no substrate can be easier during cycling whereas substrate can provide a more natural look. If you go for a sand bed, make it either 2cm or a minimum of 10cm and seed it with about 1 cm of rich natural substrate collected below low tide mark, keep it wet when collecting or bacteria will die off. You can then top up with whatever you want as long as it’s not too coarse and not too fine. Lots of debate on grain size  but I've had good success with the coarser stuff that looks a bit like coral sand, aim for around 1 to 2 mm grain size, this can be found at low tide and accumulates on the surface on mid to low tide sandy beaches and on the sandy fringes of rocky headlands. Larger shell fragments can end up trapping detritus and turning your substrate into a nitrate factory causing algae blooms and problems with disease.


    Live Rock

    Live rock is coral rock that is from an established aquarium, rock from a tropical system can be used but there may be die off in some of the bacteria. Water changes will help with any resultant ammonia spike, as a simple rule you will need 1kg of live rock per litre of water. It is imperative that the aquarium be filled with seawater at the correct salinity, pH, etc., and that all equipment is operating properly before the live rock is introduced. The more rock you have the more bacteria to support your bio load. When the rock has been placed, add dry substrate, live sand, and/or live rock pebbles as your design dictates you can top off the tank with seawater.


    Water Movement

    Another major factor in your tanks health is the gas exchange going on at the water’s surface with nitrogen gas leaving the tank and being replaced by oxygen. Sessile invertebrates also benefit from strong currents that wash away wastes and bring nutrients and oxygen to them. The return pipe from the sump discharges water in one direction only and in a continuous stream whereas in nature water movement is multi directional and intermittent. This can be achieved in the aquarium by the use of power heads or flow pumps, try to set up these flows to create turbulence and current to wash debris towards the outlet to sump. Basic rule of thumb is to have a minimum of 10 times the tank volume in water flow, if a tank is 100 litres, you want pumps equaling an output 10 times that, or 1000 litres per hour.



    . Nearly all reef tanks use a protein skimmer. A protein skimmer removes small particles of dirt, bacteria, and proteins from the water. The skimmer works by pumping the tank water slowly through a vertical or cone shaped tube, fine bubbles are injected into it by either an airstone or an air injected needlewheel pump. The bubbles collect waste on their surfaces which rise to the top as foam which builds up and flows into a collection cup. A good quality skimmer is another major tool for ensuring a long lasting tank and it is a good idea to source a skimmer with the capability to handle more than the tanks volume. There are many skimmers available in the marketplace with the new cone shaped ones seeming to be the most efficient.


    Plumbing and The sump.

    In my personal opinion having a sump on the tank is better than using canister filters; these can be used but may need the filter media washing in NSW frequently to avoid a buildup of detritus in them. Canister filters are also good for running activated carbon in to help remove toxins, phosphate removers to help with water chemistry or filter wool for polishing your water by removing particles from your water column.

    Many manufactured tanks come “ready to go.” or you can D.I.Y. it all yourself. Drilled holes in the tank and an overflow box with Durso standpipe allows only surface water to be drained to the sump usually set below the main tank. Narrow slots at the top of the overflow prevent large objects from entering the plumbing. In some designs, the return pipe passes through a second hole in the tank bottom and extends up to the top of the pre filter paralleling the standpipe. In other designs, the return pipe passes through the tank bottom at some distance from the drain. In still others, a return hose simply loops over the rim of the tank to discharge water just below the surface. A plastic part known as a bulkhead fitting provides a waterproof seal around the holes in the tank and connects to additional pipes or hoses to transport water to the sump which is usually placed underneath the display aquarium.  At the opposite end of the sump from the inflow a pump pumps water back to the main tank.


    The protein skimmer can be placed in sump or adjacent to it. Locate the skimmer where it will be easily accessible for inspection and cleaning. If you are using a chiller, it will be installed in the return line between the pump and the tank. Install the chiller’s thermostat sensor in the sump. It is a good idea to lay out the equipment arrangement on paper before you proceed with installation. You will want to make sure everything can be hidden underneath the tank while remaining accessible for maintenance.


    T5 fluorescent lighting or L.E.D.'s are adequate for most N.Z. local marine systems and will certainly create less heat into the system than metal halides will. Stronger lighting at around 10k rating is only required when housing kelp and other macro-algae, if not keeping these then you can use just normal T5 or T8 fluorescent lights in a combination of marine blue and white tubes. You will need a timer for the lighting system to keep the inhabitants in equilibrium.


    Testing the System.

    After filling the tank, plug everything in and allow the equipment to run overnight. Adjust the thermostat on the chiller, to maintain the correct temperature. Use an accurate thermometer to check the water and make adjustments to reach the target temperature. The temperature should remain constant within two to three degrees over a twenty-four-hour period. Water should be circulating from the tank to the sump and back. The skimmer should be operating, although it will produce little, if any, foam until the tank contains salt. You will make final adjustments to the skimmer after adding the salt mix or NSW, and again later after adding live rock and fish.


    Settling In with Your Habitat.

    Once you have it all in place, full of salt water and circulating let it settle in and run for a week you can take a trip to the local shore side and pick up a few critters.  Start with a cleanup crew like hermit crabs, grazing snails, chitons and glass shrimps from local rock pools, if you look under boulders (on sand) try and get some mottled brittlestars, they set up shop beneath your live rock and are brilliant at sorting the accumulating nitrogenous crap. Because of the inevitable algae blooms early in the life of any saltwater aquarium, it is a good idea to choose algae-eating snails as some of the tank’s first tenants, Cats Eyes are a good one. Have a look round locally for areas with lots of polychaete worms in a fairly course 1mm substrate. (if the worms are there, then there should also be all sorts of micro-molluscs, echinoderms and other microbial life) Also remove any large predatory polychaetes if you encounter them. They are the big pearl white ones with visible legs that can swim like eels!)


    Keep the bio load low for at least 6 months - That's the hard part, Patience,

    Let it balance out and then you can start to add your finds.


    Seaweeds are an important part of natural temperate marine habitats and provide a home for a diverse range of invertebrates as well as add movement to your display. Sub tidal red algae are the best for a closed system, with many attractive species available that will survive in an aquarium.

    The slow-growing encrusting coralline red algae are particularly attractive and suitable for aquarium life. Encrusting corallines form the beautiful pink patches coating rocks and will survive quite well under aquarium conditions try to avoid exposing them to air. Other species of red algae may be tried and often do quite well, but should be removed when undergoing rapid loss of color or deterioration. Temperate seaweeds that do well in the aquarium are generally subtidal species adapted to relatively low light levels. Most of these belong to the red algae group and make very attractive display additions.

    A simple light system consisting of fluorescent tubes (one actinic blue and one cool white are a good combination) on a 12-hour cycle should be adequate for a standard tank. Metal halide lamps can damage seaweeds collected from deeper levels than a rock pool as well as add extra heat to your system.

    All seaweeds should be collected with the holdfast intact. This attachment structure can be wedged into crevices or even glued with cyanoacrylic adhesives (super glue gel) onto the smooth surfaces of rocks (both surfaces must be dried before applying glue).

    In an aquarium with insufficient water motion, seaweeds may become smothered by detritus so a good varied flow in the water column is essential to keep them in their best condition. After all remember they are used to a more rigorous environment than can be provided in the average aquarium and will cause problems if they begin decaying.


    A few of the Sea weeds that do well in an enclosed system.

    3vSFJd60S1XlPqN6gfs13Nj3MYLvL9jTtMot61QvCoralline algae

    Coralline algae are hard and come in encrusting and upright branching varieties, extra calcium can be added to the aquarium to enhance growth, when collecting rocks try to avoid exposing them to air for too long a period as they can die off.

    BC4aibBDOo4JdrW6-hiOSOp1d26Xm_yD-_0YV-5JVelvet Weed

    (Codium fragile)

    Feels like velvet. it can at times be found above low tide usually found in sheltered harbours. Grows from a holdfast.

    Green Grapeweed (Caulerpa geminata)

    HnU8KzhWN_WDA6IMNqo9FC9M7k98YJBVLX76kXwFis sometimes found in healthy rock pools or growing sub tidally. Its roots form a growing network so can be lifted off the rock it is on in a mat, this can be bound with cotton on rock work.

    Strap Weed,

    Carpophyllum maschalocarpum

    _p_0QEpkofnVEhqWiL_NEulEDAWzu5wDAZu64uXsNeeds good varied flow , but slow grower.

    Sea Rimu (Caulerpa brownii)

    57R0zP-plG61mtax3j6i00m4h_5G1XZu4DS2cBXdThis derives its name from the resemblance to the New Zealand rimu tree. Found sub tidally in medium shelter, East Coast North Island. This plant grows from runners, use Super Glue Gel or cotton to re attach.


    A Clean-Up Crew for Your Aquarium

    The “clean-up crew” is a term used to describe the various small invertebrates that in nature clear up decomposing matter, algae growths and sift through the sand bed to help promote a healthy system. The most commonly used are hermit crabs, turbinaria snails, and glass shrimp though there are a variety of other snails, limpets, brittle stars, etc.

    One important factor to consider is the type of habitat you are trying to replicate and the compatibility of live stock in the tank. Leatherjackets, Puffers or wrasses can predate on hard and soft bodied invertebrates so you may be limited to animals with a hard shell; large snails and hermit crabs

    You also need to ensure there is enough food in the tank to sustain them,

    a newly set up tank may support a few shrimp or hermit crabs as these can be fed easily. Whereas grazing snails will possibly starve until the algae levels are up in the tank, unless you can supplement feed them, some clean-up crew members require a sandbed for survival and a new bed may not have enough nutrients required to support them.

    It's Important to check on invertebrates to ensure that they are still alive, a good rule is to keep track of any livestock you put in the tank as dead animals can quickly pollute the water in your tank.

    Sometimes the clean up crew can predate on each other, for example Hermit crabs are known to kill snails when they need a new home so adding spare empty shells will help solve the problem.



    Black Spotted Topshell

    Diloma melagraphia atheops

    Diet: Grazes on algal film and also detritus


    Cats eye Snail

    Turbo smaragdus

    Diet: Foliaceous algae and macrophytes


    Cooks Turban

    Cookia sulcata

    Diet: Foliaceous algae and Ecklonia radiata


    Turret Shell

    Maoriculpus rosea

    Diet: Deposit feeder, filters sediment.


    Glass Shrimp

    Palaemon affinis

    Diet: Almost anything


    Brittle Starfish

    Diet: sediment deposits detritus feeder


    Sea cucumber

    Stichopus mollis

    Sea Cucumber are detritus feeders, they are very good at keeping a sand bed clean.



    When it comes to setting up a saltwater aquarium, big tanks and small ones differ only in the amount of water and materials involved. The basic procedure is the same. After readying the tank and setting it in place, install the equipment. Test the plumbing with fresh water, and make sure everything else is working properly before adding salt mix.

    Aquascaping is next, using live rock and sand, or non-living materials, or a combination. Allow for a break-in period as the aquarium develops a population of beneficial micro-organisms, from this point on, you are the custodian of a living ecosystem. You must maintain the aquarium over the next several months to allow basic biological processes to develop appropriately.

    The aquarium will continue to mature and change for a period of months. Early on, for about six to eight weeks, you can expect a series of algae blooms to occur, typically, brownish diatoms and red/purple slime algae appear first then later, filamentous green algae supersede the earlier growths. This waxing and waning of algae blooms is normal, you can siphon out patches of slime algae, and use a pad to clean the glass, but do not reduce lighting in an attempt to limit algae growth. You will only prolong the process, algae grows because the water contains compounds, such as phosphate, that stimulate their growth. Removing algae from the tank helps to export the compounds. Protein skimming also helps. You will note that the skimmer begins to produce foam during the break-in process. As micro-organisms grow, reproduce, and die, they release organic compounds into the water, some is taken up again by other organisms, and some is removed by the skimmer. As the developing ecosystem becomes more and more stable, you can introduce additional invertebrates and fish about every two weeks. Although the process of stocking an aquarium can be slow, patience is rewarded with a thriving, easily maintained tank.




    Maintenance of your system requires little apart from the suggested routine.

    Daily:check temperature, equipment and check and feed inhabitants.

    Weekly:check salinity, adjust as needed; check pH, adjust as needed; carry out 10 percent water change; clean algae off glass

    Monthly:check nitrate; carry out 50 percent water change; replace detritus removal pads in sump; siphon out debris as needed


    Semiannually: carry out 50 percent water change, clean power heads if needed.


    Annually: replace lamps; service system pumps, skimmer etc.




    Go slow, keep your bio load minimised, and you'll be fine.


    Feeding the livestock.

    A proper diet is essential for your livestock to flourish, generally fish are not fussy and can be fed squid, mussel, krill, shrimp, fish and commercial frozen foods in pieces small enough to fit into their mouths. It is essential that some species of wild caught stock are fed live foods until you are able to get them onto other foods, seahorses and plankton feeders being prime examples. Live foods can be bred by you such as  Brine and Mysid shrimp or supplemented with mosquito wrigglers, daphnia or white worms, if you live near the ocean you can collect your own. Running  a fine net through seaweeds in a tide pool or round weed covered boulders will usually produce a plethora of various small shrimp, amphipods and copepods. Excess food collected can be kept in fresh NSW with an airstone or frozen then fed out, this is useful to help wean them onto commercially available foods. Generally fish will eat foods they recognise as part of their natural diet.

    Some types of fish can be too slow or shy to compete for food with faster moving individuals or indeed may be considered prey by them, these types are better housed together to ensure longevity.. Knowledge gained from nature guides, websites and experience should give you an understanding of the feeding requirements and compatibility of your livestock within your aquarium community.

    Feeding invertebrates presents more of a challenge because they exhibit a far greater diversity of feeding styles. Some invertebrates, such as sponges and tunicates, filter tiny plankton particles, while others graze or prey on more substantial items. In general, filter feeders are the most difficult to satisfy in the aquarium and should be avoided in favor of those that select larger foods. Some time should be devoted to learning about the general feeding habits of each invertebrate species you plan on maintaining. This will help to avoid such mishaps as adding large predatory sea stars that will ravage your beds of sessile invertebrates.

    Collecting for the aquarium.


    Some of our local species of fish come under the Quota management system and therefore have a minimum take size, so some care must be taken when collecting for the tank. Other than these species one can collect stock from local rock pools or on fishing trips, i use barbless hooks for this and try to catch from shallower water as catching from deeper water may mean having to deal with an over inflated swim bladder. I always take large plastic containers and ensure the water is changed every 20 minutes or so to keep oxygen levels up for the fish, battery powered air supply or 12v bilge pumps are good for keeping water flow up. Acclimation is ideally the same as for tropicals and having a quarantine setup is best, beware of fast changes in temperature or salinity, anything more than 3 degrees C. in collecting or  moving temperate species can lead to problems.




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