Saltwater Aquariums Explained

June 2012
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Saltwater Aquariums Explained

With the right setup, keeping and maintaining a saltwater aquarium is not much harder than freshwater. It does require a little more of time and maintainance compared to keeping freshwater aquarium but it is a really rewarding experience. Depending on whether you want to create a reef aquarium complete with living corals or a fish-only-tank, the equipments needed will have to be chosen with care. It is more practical to do it once right the first time than having to go through the pain and cost of losing your favourite pets by not having a proper setup. In general, saltwater aquarium setup can be catergorised into three;
Fish Only Tank
Saltwater fish only tank setup generally is no different to the average freshwater tank system. In most cases, the only difference is the use of coral sand as the bottom cover and the fact that the water is salty. Please note, we would recommend keeping hardy or aqua-cultured fish such as damsels and clownfishes with this setup as it has many limitations. We would only recommend this kind of setup as a quarantine or hospital tank for housing fish temporarily.

Fish Only With Live Rock Tank (FOWRL)
FOWRL tanks use only live rocks as the main source of filtration instead of bio balls and ceramic rings. Why live rocks are good substitute of bio balls? They provide a more complete filtration that allow the complete breakdown of nitrogenous waste. This is possible because there are many different strains of beneficial good bacteria living within these rocks, both aerobic bacteria that requires plenty of oxygen living on the outer layer and anaerobic bacteria living deep inside the cavity of the live rocks. Anaerobic bacteria live in low oxygen environtment and breaking down Nitrate (NO3) provides them with a source of oxygen. That is why live rocks is a better option compared to bio-balls which only serves a home for aerobic bacteria that only converts ammonia to nitrate which is why it is often refered to as the "Nitrate Factroy".

The added benefit of using live rocks is that they make excellent hiding places for your tank inhabitant as well as serve as a good source of natural food for your fish. Algae and small crustaceans that seek refuge within these rocks generally have a chance to multiply and serve as an excellent snack for your tank inhabbitants.

In FOWRL, the use of better lighting and protein skimmer is crucial.  Protein skimmer will help remove unwanted waste which makes up for the need for performing large water changes. Lighting plays an important roll in providing the much needed life support to grow coralline algae and other organisms within the live rocks which will in return create a natural balance in the aquarium.

FOWRL setup is usually chosen to keep large predatory fish such as morray eels, stingrays, sharks, lionfish, triggers ect and fish that feeds specifically on corals such as butterflyfish, large angels, puffers and certain type of wrasses.

Reef Tank
This is normally the next step an aquarist took after succesfully keeping a FOWRL. FOWRL can easily be converted into a reef tank with a few addition of equipments. A little more in depth knowledge of coral needs and water chemistry is key to successful reefers.

In a broad generalisation, coral needs are: sufficient lighting, good water movement, food, supplements and good water quality.

Although every single coral needs and behaviour have to be studied individually, they can be categorised into three different types; Soft corals, Large Stone Polyp (LPS) and Small Stony Polyp (SPS).
  • Soft coral – tolerate slightly richer nutrient water especially in terms of Nitrate (NO3) & Phosphate (PO4), most are happy with less lighting, and not too fuss with water movement. They can be placed close together as they do not have powerful stinging cells. Feed mainly phytoplanktons.
  • LPS – Less than 20mg/L NO3 and minium PO4 level is preffered. Calcium, magnesium, strontium needs to be maintained as they are absorbed for growing their skeleton. Lighting and water current needs may be higher compared to softies. Placement in tanks is important as they have the most powerful stings and can kill each other when placed too closely together. Allow room for growth. Feed larger zooplankton even mysys, brine shrimps and krills.
  • SPS – requires optimum water quality, very strong light, strong turbulent current and very stable environment. These form the fastest growing corals that is very hungry for calcium, magnesium and strontium. Stable level of salinity, temperature, pH, alkalinity, calcium and magnesium is crucial. Without supplementation the level in your closed environment is quickly diminished. Calcium reactor, kalkwasser stirrer or automatic dosing pump is generally required to keep these corals. Feeds on phytoplankton and rotifers.
Are corals animal or plant? Corals have a symbiosis mutualism with algae that they keep within their body called the zooxanthellae. The zooxanthellae photosynthesize like plants and they share the energy with their host coral. Most but not all corals have these attribute. There is another way corals can obtain energy from which is through direct feeding. As explained above, food varies from the smallest phytoplankton, zooplankton to as large as chopped prawns.

The first step to creating an excellent sustainable reef tank is to build the right setup with the right equipment. With the advancement of technology, there are now equipments available to make your life a lot easier as well as making sure that the living condition in your man-made reef much more stable. I will try to go through some of these equipments needed:

The Tank
Go for as large as the space in your home and your budget allow as the larger the tank is, the more stable and the more forgiving it is. No matter how tempting it is, less than 80L nano tank is only to be attempted by a more experienced aquarist! Opt for a wider tank instead of a slim one as it will allow you to arrange the corals in steps for better illumination so they don’t overshadow one another.

The Filter
At Aquaristic, we encourage a more natural approach of using live rocks, protein skimmer, refugium and Deep Sand Bed (DSB) as the only source of filtration in the system. We are not recommending the use of bio balls or other biological medias such as ceramic rings and other porous biological media for a reef tank as they tend to become a nitrate factory.

Whenever possible, we would always recommend using a sump which is a second tank underneath your main tank where all the equipment and filtration equipments can be housed. Most sumps is partitioned where heater, protein skimmer, pumps, refugium and DSB can be placed in different chambers within the sump tank.

Refugium is a stage in the sump  where macroalgae (caulerpa sp.) grows. A healthy macroalgae will absorb nitrate and phosphate very quickly from the water and you can remove nitrate and phosphate by pruning these algaes thus they often refered to as the "algae scrubber" or "nutrient export". In order to grow well, macroalgae needs a source of lights to help them photosyntesize. The best thing to do is to alternate the time the lights are turned on between the main tank and refugium. This helps maintain a more balanced pH in the tank. When the lights in the main tank are switched off, corals breathe out Carbon Dioxide (CO2) which will react with water to form carbonic acid lowering the pH in the tank. By having lights on on the refugium, the macroalgae are allowed to start consuming CO2 to photosynthesize thus creating a more balance pH throughout the system. Another additional benefit of having a refugium is it creates a safe-haven for copepods and amphipods to multiply which will eventually get washed in into your main tank providing free and nutritious live food for your fish.

The Light
There are  a lot of lighting options available in todays market. T8, T5, PC (power compact), metal halide and LED to name a few. I will try to give a brief summary of what we think about these lights:
  • T8 - Least expensive to purchase and runs cooler compared to the other options. The downside is T8 does not produce strong illumination and more bulbs are needed to compensate when used to illuminate more light demanding corals. The spectrum in the bulbs burns quite quickly and need replacing in 8-12 months time. Would probably only suits low light soft corals.
  • T5 - Produce higher intensity output compated to T8 and there are a lot of different colored bulbs available in the market providing a more complete color spectrum for optimum coral growth. This is probably still the best option if you wish to bring out the best color in your corals. SPS can be grown under this lighting provided you have enough bulbs to get the right intensity. The disadvantage of choosing T5 is that they also produce a lot of heat and T5 units are more expensive compared to T8. In 10-12 months bulbs need to be replaced and they too are costly.
  • Power Compact (PC) - Some PC can be as powerful as T5. The bulbs are U-shaped and comes in different colors. Bulb replacement tend to be cheaper for PC compared to T5. The downside is, like T5, it generate a lot of heat.
  • Metal Halide - It is still the light of choice for many reefers. Very powerful light source, penetrates a lot deeper and it produce a "shimmering effect" just like sunlight. A good quality metal halide unit is quite expensive and halides use more electricity compared to the other options. Chiller is usually needed as metal halides also runs very hot.
  • LED - Eversince a year ago, a lot of aquarist make the switch to LED because of its benefits. Some of the attractive features of an LED unit are; produces more output compared to the amount of electricity used, runs very cool, provide more diverse color spectrum like T5 and expensive units come with build in micro-computers that allows the "sunrise" "sunset effect. These units can be programmed to allow for cloud cover, lighting, moonlight ect. One more attractive attribute to LED is their bulbs are often said to last 50,000 hours which is equivalent to 10-20years. Although can be an expensive investment, not having to buy 3-5 years of T5 or metal halide bulbs is often enough to compensate for the initial price you pay for an LED unit...not to mention the money saved from the much lower electricity cost. LED really sounds like a dream come true but please BEWARE that not all LED are alike. Not all LED units will give you the benefits I mentioned above. I do not have the qualifications to write in depth about LED and light but I have tried using quite a number of different LED brands on our shop display system so whatever I will write next is based on my experience as an aquarist. I believe each LED has its purposes and that we will get what we pay for.
The Water Movement
Having a good circulation throughout your tank is important. Try aquascaping your live rock so that they have less contact to the floor as possible (but still sturdy). This is important as detritus tend to build up in areas where the live rocks touch the sand. Aquascape your live rocks so that they are not too stacked up on top of one another as remember, your beneficial bacteria that lives within these rocks needs good circulation for oxygen. It is quite pointless to try to squeeze too much live rocks into a tank which will end up being a dead due to these bacteria not getting enough circulation. The wave maker and powerhead that produce wide angle current are the necessaryequipments to have as they allow you to have current source from different directions. Although costly, programmable pulsing powerhead is a very good investment.

Temperature Control
Heater is necessary in winter times. Chiller may be needed in summer times, although in certain setups they are not an absolute must. Sumps that act as a cooling reservoir of water and the use of cooler LED lightings allow for the use of cooling fan instead of the expensive chiller. Stable temperature of between 25-27° Celcius is what every aquarist should try to achieve.

Refractometer vs Hydrometer
Knowing the salinity level which is the salt content in your aquarium is very important. Hydrometer or refractometer are used to obtain this reading. A hydrometer does not tell you the exact salinity but will give you quite an accurate estimate of one. It measures the density of your salt water but can sometime deviate due to water being of a different weight depending on temperature. Refractometer generally cost twice as much but is most accurate. Do not ever attempt maintaining a saltwater aquarium without the use of any of these devices.

Helpful but not a-must-have optional equipments:

Osmolator or Automatic Water top Up
When the tank water evaporates, the salt stays thus the salinity in your tank increases. Therefore, fresh water top-up is necessary to maintain a stable salinity. The frequency of freshwater top-up depends on several factors. Daily freshwater top-up may be needed for nano tanks as a small level of evaporation can cause the salinity to jump up to the roof. That is why nano tanks are harder to maintain compared larger ones. An osmolator is basically an automatic freshwater top-up machine. It has a sensor or float switch that instructs a pulsing pump to inject freshwater into your tank from a reservoir of freshwater.

Automatic Dosing Pump
Overtime, elements in your aquarium gets depleted especially if you are keeping lots of hard corals. Calcium, alkalinity, pH, magnesium are absorbed relatively quick depending on your stocking level. Clams, corals, coralline algae and a number of marine invertebrates uses these elements to grow thus a weekly or bi-weekly dosing of these elements help in maintain a stable balance in the tank are necesarry. An automatic dosing pump does this automatically and most can be set to dose at a small rate of six times a day creating much more stable element levels compared to a high dose once a week.

Phosphate Reactor
Phosphate which comes from fish waste, tap water, supplements and food tends to build up over time. Most corals prefer a phosphate reading of close to zero and some may even turn brown very quickly in the presence of phosphate. A Phosphate reactor is an external chamber where a chemical absorption media such as Rowa Phos™ and Seachem Phosguard™ is added to absorb the excess phosphate in the water.

Nitrate Reactor
In most circumstances, nitrate generally can be removed through the use of live rocks and refugium  but sometimes it can be stubborn. This is when a nitrate reactor comes into play. Nitrate reactor is an external vacuum canister chamber that encourages anaerobic bacteria growth that feeds specifically on nitrate.

Reverse osmosis and deionization unit. This device frees your tap water of all impurities. Personally, I don’t use RO/DI unit myself but using one really elevate your chances in providing the best water supply for your beloved aquarium. RO/DI eliminates any unwanted impurities such as phosphate and nitrate which will help you to be more in control of algae.

Useful especially in summer months to help maintain more stable temperature. The use of sump filter which acts as a cooling reservoir and LED lights that runs cooler eliminate the use of chillers in larger setups.

Calcium Reactor
External chamber which is filled with Calcium stones. Carbon dioxide tank and pH computer is also required for this to work. The pH computer monitors the pH level in the main tank and if it drops, it will signal the carbon dioxide to be dosed directly into the calcium reactor thus when it turns into carbonic acid, it will dissolve the calcium stones which is then dosed into the main tank to increase the calcium level. Great to be used in SPS tank in a larger setup.

Kalkwasser Reactor
Calcium hydroxide powder which has a high alkalinity, pH and calcium can be placed inside this external chamber that has a stirrer that keep the dense powder mixed up with in the water within its chamber. Normally comes with a float switch that measures the water level in the main tank or sump. When water evaporates, the switch will signal the kalkwasser reactor to dose top up water that is mixed with the calcium hydroxide powder thus maintains your pH,kH and Ca at the same time. Great to be used in smaller setups with high evaporation level.

The next step is MAINTAINANCE...  Prepare to spend time to get to know the world you created and do what needs to be done to maintain that world. Every aquarium is its own little world and no two systems are the same. Each will have different needs and no one can tell straight away what element to dose and how much, how often to do water change, how much to feed, how long should you turn the lights on and so on. You have to be prepared to learn about your system, see what it needs and dose accordingly. DO NOT ever try to dose chemical without TESTING it first. Before you buy supplements, buy a test kit and start writing a journal.

The maintainance routine of a FOWRL is no different to a standard freshwater tank so I won't touch on that. The following routines is for a reef setup:

Daily Routine:
- Feed the fish and check is everyone is swimming and behaving normally
- Feed your corals two to three times a week. LPS corals will feed on larger zooplankton such as baby brine shrimp to large brine shrimp and mysis shrimp while SPS and softies will feed on phytoplankton and rotifers. Reef-Roids is a great product that has a blend of different phytoplanktons.
- Check you equipments to make sure everything is running properly
- Check temperature in the tank. 25-27 Celcius is good.

Weekly Routine:
- Test your water parameters and record in a journal:       
  • Salinity - Try to maintain a stable salinity level of 1.023-1.025
  • Nitrate (NO3) - the lower the better but try to maintain below 20mg/L
  • Phosphate (PO4) - the lower the better but try to maintain below 1.0mg/L. NO3 & PO4 tests will tell you whether your water changes regime is sufficient, whether you are overstocking or overfeeding.
  • pH - 8.0 to 8.5 is good
  • Alkalinity (kH) - Carbonate hardness of 8-11 is the goal depending on your salinity level.
  • Calcium (Ca) - 440mg/L
  • Magnesium (Mg) - 1400mg/L. kH, Ca and Mg is what is used up by hard corals, coralline algae, and a few marine invertebrates. They get used up and if not replenished, will deplete very quickly depending on the type of corals that you keep. Most salt mix products have already have a high concentration of these elements so most of the time, when majority of the corals you keep are softies, these supplement additions are not necessary.
- Change 10-20% of water. Sand vacuuming is a great practice to remove trapped detritus.
- Wipe the glass using filter wool and scrape some stubborn algae using plastic scrapper.
- Clean your protein skimmer cup
- If you are pedentic, remove nuisance algae using a pair of tweezers and suck them out using a small hose. Hunt for pesky aiptasia or glass anemone. A great product I use in the shop is Aiptasia X from Red Sea.
- Depending on your dedication level, dosage of certain elements will help keep your corals vitality and color.
  • Vitamin, Amino Acids & Carbohydrate
  • Iodine
  • Strontium
  • Chelated Iron
- Because your live rocks contain the diverse fauna of different strains of good bacteria, proper routine maintainance is necessary to keep them healthy. Using soft toothbrush, brush of the rock surface gently. This removes detritus build up and open the pores of the live rocks. Overtime, certain bacteria strains can overtake others so it makes sense to re-generate those strains back. There is a great product from Dupla Marin (literally prodibio) which contains the complete bacteria strains as well as the food for them called Dupla Marin Bacter M™ and Bacter Booster™.
Monthly Routine:
- Clean all impeller pumps including your protein skimmer.
- Wipe clean light covers as sometime there is salt build ups.


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