Starting a beautiful marine tank is exciting. But upon doing research online, the information may be overwhelming, contradicting & often confusing.
This guide aims to provide a high level overview of areas to consider when embarking on the reefing journey. To help you make educated choices in planning & purchasing the right equipment.
Most of the article will refer to a reef tank.
General planning :
What do you want to keep?
The most popular set up is a reef tank – a mix of both fish & corals.
And when it comes to corals, there are options of LPS (Large Polyp Stony Corals), SPS (Small Polyp Stony Corals) and softies. In general, LPS & softies are easier & less demanding than SPS. LPS are more tolerant of imperfect water conditions, require less flow & less light. On the other hand, SPS demand pristine water conditions, strong flow & very strong light. These affect your equipment choice.
Another popular setup is a fish only system with no corals – commonly abbreviated as FOWLR (Fish Only With Live Rocks). For example, beautiful fish like Angelfish eat fleshy corals & nip on SPS are best kept in FOWLR systems.
Less common is a species tank, where certain species have specific requirements. For example, seahorses are weak swimmers and require very low flow in the tank. They are compatible with most soft corals and gorgonians. You must avoid any stony corals that have a strong sting as this often leads to injury & infection.
AIO (All in One) tanks. These are usually smaller setups ranging from 10L to 300L. The compartment to place small filtration equipment & bio media are at the back of the tank. AIO tanks are great for reefers with limited space or those starting out to learn the ropes.
Display tank with sump (Recommended set up for marine tanks). A sump is an additional tank usually below the main display tank where equipment and additional filtration capabilities can be enabled. You can have proper mechanical filtration, large skimmer, more biological media and multiple media reactors. A sump allows easy access to the filter & equipment which makes maintenance easier which typically leads to a more successful tank.
For both the AIO and Tank/Sump options, you can choose from purchasing ready made system, or to have them custom designed.
- Ready made tanks have the necessary components included and are more straight forward to set up.
- Custom made tanks offer options such as tank size, glass type, overflow, piping & cabinet customization. Approach your local fish shop for further advice.
Simple bare tanks (not recommended for a marine reef aquarium). There are some who covert their simple & bare freshwater tanks to saltwater. And attempt to re-use the tank by using canister filters or hang on back filters. Such setups are not recommended as the filtration is not adequate. Using an external canister filter is troublesome & will result in neglect & possible failure. On the other hand, a simple bare tank is adequate as a short term quarantine/hospital tank.
Once you have decided on the tank type, start planning for some other equipment. Namely :
Return pumps move water from the sump or IOS compartment back to the main display section. The 2 main types are DC (Direct Current) & AC (Alternating Current) pumps. DC pumps allows adjustable pump speed but are more expensive than AC pumps. DC pumps are useful if you plan to T-off the return pump for reactors & chillers. As you add more equipment, you can adjust the pump speed accordingly.
AC pumps have fixed speeds. You need to purchase the right size for your needs.
Turnover rate from sump to display tank of about 4x is sufficient. For example, for a 500L tank, a return pump speed of 2000l/hr (liters per hour) is sufficient. Note the advertised flow rate on the box depicts maximum flow of a pump (no pipe restrictions or height pressure losses). In a tank system, pipe restrictions (bends, elbows & valves) slow the flow rate down. A general rule of thumb is to assume it slows the pump flow rate by half.
If you T-off the water flow (i.e. feed water to other equipment as well), then pick an even higher rated pump accordingly. With a DC pump, you can easily reduce the power & flow rate.
Wavemakers & Flow
Flow is important for a healthy reef tank to bring oxygen & food to the corals.
Most popular wavemakers allow adjustable propeller speed & duration. The goal is to create pulses & random flow patterns in the tank, just like in the ocean.
Size the wavemakers correctly for your tank size. Do not place them directly in front of corals as the continuous direct flow will damage coral tissue. Larger tanks will require more wavemakers for better coverage.
Some higher end wavemakers have the motor outside the tank and magnetically coupled to the propeller/wet side inside the tank. This unique feature with 2 key advantages
- Motor heat is not absorbed by the water.
- Allows the wet side be removed easily for cleaning.
Another popular design are gyre pumps which use a different style fan blade to produce wide laminar flows. You will need fewer wavamakers in a tank with these since they cover a wider flow width. The downside is these pumps tend to be more troublesome to clean
The 2 common light options are T5 & LEDs.
T5 provide a blanket of diffused light to the entire tank so there is less shadowing of corals. You can configure it with different light tube types (colour temperature). While T5 fixtures have lower up front cost, the T5 tubes should be replaced every 9-12 months – they deteriorate & become less bright.
LED light fixtures are the more popular choice these days. While they may have slightly higher initial cost, a good LED set should last many years. LEDs are extremely efficient and can produce a lot of light and less heat compared to T5. You have the flexibility to tune the light to simulate sunrise, daylight & sunset. Or tune the spectrum based on personal preference or to the type of corals kept.
Depending on the tank size, rock scape & type of corals kept, you may need multiple sets of LED fixtures to provide sufficient light energy for the corals to thrive – similar to the energy they receive from the sun.
LED lights are typically mounted about 30cm from the water surface level. This should provide good light spread & not have hotspots (areas of concentrated light which can burn corals)
PAR (Photosynthetically active radiation) is measure of the amount of light available for photosynthesis. Corals, clams & other animals originate from different depths of the ocean and have different PAR requirements. In general SPS need more PAR. Conversely LPS require less PAR. Having too strong light can also cause corals to bleach & die. Measuring the PAR levels using a PAR meter takes away the guess work of coral placement. Ask around the reefing community to loan or rent one.
The general guideline is to have about 6-8 hours of bright light for the corals to photosynthesize. It is common to have a few hours of bluish light at night to enjoy the beautiful glow of the corals. This is more of an individual preference. Below is an example of a light profile.
There are 3 main types of filtration – Mechanical, Biological & Chemical.
Mechanical filtration is the use of physical media or equipment to trap solid particles from the water. These are often placed in the 1st stage of the sump or IOS filter system to trap large particles before they clog the pores of biological filtration media. Key points :
- Filter wool. Made of synthetic material. A cheap & convenient option. Use & discard
Filter sock. More elegant solution but more costly. Socks are made of nylon or felt. Nylon socks are easier to wash under the tap but has less filtering capacity compared to felt socks. Felt filter socks are quite inconvenient to flip & wash thoroughly. Sock pore size are typically in the 200-300 micron range.
Filter rollers. These automatic filters use a thin sheet of filter material (known as fleece) to capture dirt. A motor advances the filter material automatically when clogged. By removing food/dirt quickly from the water, filter rollers ensures minimal decay & contamination of the water. Fleece pore size are in the 25-50 micron range. A roll of fleece should last about 1.5-3 months
Protein Skimmer is also another form of mechanical filtration. Often placed after the initial filter wool/sock/fleece. A skimmer uses a needle wheel pump to generate large amount of fine bubbles. This causes organic waste (fish food, fish waste & suspended particles) to stick to the surface of the bubbles which bursts when it reaches the top of skimmer. The splattered waste then flows into the collection cup. Having a good protein skimmer results in cleaner water & less frequent water changes. Protein skimmers have a secondary advantage of improving gas exchange & increasing the oxygen content of the water due to the bubbles it forms.
Biological filtration refers to the use of bacteria in the tank to break down dangerous ammonia to less toxic nitrite & nitrates; commonly known as the nitrogen cycle. A term often mentioned in articles is ‘live rocks’ – this refers to a rock where bacteria reside.
Current trend is to have minimal rocks in the display tank so that there is more space for corals & fish to swim, and the supplement with additional biological media (eg. ceramic balls, cylinder or blocks) in the IOS or sump to increase the surface area/population of this beneficial bacteria. Place loose media in a mesh bag or basket for easy removal for the occasional quick rinse with old tank water.
Chemical filtration is a way to removed dissolved particulates using activated carbon, resins or other absorbent media.
- Resins for absorbing phosphates
- Activated carbon to remove toxins/clarify water.
Chemical filtration media are best placed in a reactor to enable sufficient contact time between water & media for the reaction to take place. A less effective but acceptable alternative is to put the media in a mesh bag placed in a high flow area.
Given the warm ambient temperatures here in Singapore, there is a need to cool the water to the 26-28 degree Celsius range.
Cooling Fan. For those on a budget & smaller tanks, you can get away with a cooling fan blowing on the water surface. With this method, evaporation rates increase & you must have a good auto top up system to replenish the evaporated water quickly. Else, water parameters (eg salinity) will have big swings which is bad for livestock.
TEC (Thermo Electric Chiller). An alternative for very small tanks (10-30L range) is a mini chiller using Peltier cooling technology. Such mini chillers are not very energy efficient (about 5% of electrical energy is used for cooling). They have a typical equipment life of 2-3 years.
Chiller. A more energy efficient option is the refrigerant type chillers. Select one that is correctly sized for your tank.
Electricity cost is not too high. One example of usage for a 1/4hp (~440 watts) chiller running 20min to chill. Turns on once every 3hrs to maintain a tank between 27-28degC. Based on rough calculation, this works out to SGD $0.21 per day. Or SGD $6.40 per month.
For larger 4ft & larger tanks, it is common to use an non-invertor air con compressor with cooling coil. The compressor is best placed outside the house so the hot air goes is blown away. If this is not possible, it is also possible to place the compressor next to the aquarium. Compressors are extremely efficient & cools the tank fairly quickly. For example, a 4ft tank may take about 20min to cool and turns on once every 3 hours.
Auto Top off
Water will naturally evaporate from the aquarium. Evaporation rates can be much higher when using a fan to cool the tank. As we are dealing with saltwater, only the water component evaporates (the salt remains). Salinity increases if no fresh water is added and leads to unstable water parameters.
An Auto Top Off (ATO) is a device that detects the water level in the tank or sump. If it is too low, it then triggers a pump to top up fresh water from a reservoir back in.
Take note the ATO should be using water only & not salt water (since only the water component evaporates)
….. to be continued in Part 2