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Starting your first marine tank. Overview to plan your equipment and budget (Part 2)

Starting your first marine tank. Overview to plan your equipment and budget (Part 2)

This is a continuation of a 2 part series.


The ideal situation is to start the salt mix with the cleanest possible water. RODI (Reverse Osmosis De-Ionize) filters produce pure water by deploying a series of filters to remove sediments, chlorine and other contaminants such as copper, chromium, ammonia, nitrate & phosphorous that may be present in tap water.

A typical RODI system consists of

  • A polyester filter to remove sediments
  • 2 carbon blocks to remove chlorine & other contaminants
  • Reverse Osmosis (RO) membrane that performs the majority of filtration,
  • followed by de-ionisation (DI) resin to remove the remaining dissolved solids.

The ultimate goal is to produce 0 TDS (Total Dissolved Solids). Measure this with a handled or in-line TDS meter.

While the RODI filter may seem expensive, the convenience will pay off in the long term.

RODI system will generate some waste water (that’s how the RO filter works). Some reefers collect the waste water to be re-purposed (laundry, washing floor).

RODI systems need at least 50psi water pressure to operate efficiently (i.e. able to push water through the RO membrane). Generally higher pressure will result with less waste water. If your home does not have such high pressure, then an additional water pressure booster pump needs to be installed. Hot tip : If you live in a high rise apartment, collect water late at night or very early in the morning. Water pressure tend to be higher (because there are less people using water)

For smaller tanks that do not need much water, a more economical option is to use an DI filter which skips the reverse osmosis (RO) membrane.

It is possible to use tap water with anti-chlorine. However, there is a chance of letting contaminants slip through – possibly leading to algae growth or coral/fish health issues.

Salt mix

 You make saltwater by mixing RODI with aquarium salt. Some brands are made from evaporated sea waters while others are synthetic. Both are good.

For reef tanks, prepare your salt mix in a large container or water drum to a salinity of 35PPT (parts per thousand) or 1.026SG (specific gravity). There is a misconception that the ideal salinity is 1.025SG. The general accepted natural sea water salinity is 35PPT.  For fish only tanks, it is OK to use 30.5ppt or 1.023SG

Salinity is best measured with an optical refractometer. NEVER use a swing arm hydrometer as they are extremely inaccurate.

Key parameters & testing

It is important to test your water parameters weekly to ensure the well being of your livestock. Fluctuations will result in nuisance algae, cyanobacteria bloom & even fish death.

With testing, you will know which parameter has drifted & be able to quickly adjust it back. Similarly, by testing the water, you ensure your dosing regime is done correctly.

Experienced reefers may get away with not testing their waters since they may have their processes dialled in. But for new reefers & new tank setup, best practice to test weekly (or even more often for a start).

Home test kits are available for the parameters highlighted in bold blue font below. Column in green shows the target for my own tank.

Trace elements and heavy metal contaminants that cannot be detected with home hobby test kits. Once you have set up the tank and settled into a dosing routine, consider going into the next level of testing by sending your water for external ICP (Inductively Coupled Plasma) testing. LFS organise water collection occasionally. Depending on the brand, these typically costs between S$60-S$120 per test.


Sufficient water change can be done to replenish depleted elements. Water change alone may be possible for small tanks but impractical for larger ones. Hence, adding back elements such as Calcium, Magnesium & Alkalinity can be done using a dosing pump or a calcium reactor.

If you have corals, you should also add trace elements (needed for biological cell function) and amino acids (building blocks of protein needed by animals)

There are many additive products and brands in the market. Do not be tempted to try too many products as some may have overlapping effects. When dosing a new product, take the conservative approach to dose half the recommended amount first. Monitor & adjust the dose accordingly.

Tank maintenance requirements

Water change is a way to reduce nutrients (nitrates, phosphates, waste) by diluting it with clean water. Water change also replenishes depleted elements. A general guideline is to change 20% of water every 1-2 weeks. It is a good idea to siphon the sand bed during water change to get rid of trapped detritus.

Clean the glass. A healthy tank will have some bio film & algae growth on the tank after a few days.

Magnet scrapers are popular. Be careful not to get sand trapped between the cleaner & the tank glass/acrylic as this can scratch the glass. Some have magnetic blade attachments which is an efficient way to scrape off stubborn algae.

Hand held scrapers are good for hard to reach areas and close to the sand bed. Do not apply excessive uneven pressure when using hand held scrapers as they tend to scratch glass easily.

If you have an acrylic tank, use only cleaners with a soft  cleaning pad. Metal blades will scratch acrylic.

Cycling & adding livestock

Once the tank is set up, cycle the tank with bacteria additives. This takes about 4-6 weeks to complete. After which you can start to add livestock slowly. Read up about care requirements & whether your aquarium set up is ready or suitable for it. Key points :

  • Marine fish can be territorial & aggressive towards fish of similar species, shape or color. Some are just bullies to everything else
  • Aggression often lead to injuries, stress & often death. Check compatibility
  • Corals of the same family in general will not sting each other. Corals can be aggressive & sting corals of other species.
  • Some fish or invertebrates eat corals.

Leon tan

Leon Tan, who goes by the nick SubzeroLT has been in the hobby since 2014. An avid reefer & photographer, his tank thread series on SRC forum “My Slice of Nature” highlights several DIY projects, equipment trials & more recently about 3D printing.