We have put together a collection of FAQs that we believe will be helpful to any reef aquarium hobbyist. Whether you are looking to buy your first RO/DI system, upgrade your existing system or need help deciding if you really need one, you are bound to have questions and we can answer them.

If the following content does not provide the answers you need, please don’t hesitate to contact us. Our aim is to make sure you get all the assistance you need and we are always too happy to help.

Where is Reef Pure RO Systems located?

We are located in Brisbane, Australia. Our business is 100% Australian owned and operated. We are very proud to be the first RO system supplier in Australia to specialise in supplying Australian reefers with reef aquarium specific RO technology.

What is Reverse Osmosis?

Reverse Osmosis is a process in which dissolved inorganic solids, such as salts, metals and many other impurities are removed from the water. This is achieved by household water pressure pushing tap water through a sediment filter, carbon filters and lastly a semipermeable membrane.

This process generally achieves a rejection rate of >98% when using high-quality TFC (Thin Film Composite) membranes, like those supplied with all of our systems.

What is DI resin and why is it important on an RO system?

DI (deionisation) resins are ion exchange resins which are used to produce deionised water or what we usually refer to as DI water. These resins are made up of small plastic beads, composed of organic polymer chains that have charged functional groups built into the resin bead itself. Each functional group has either a fixed positive or negative charge.

A small number of ions which are electrically charged atoms or molecules are found in water, even after the reverse osmosis process. The ions have either a negative or positive charge and made up of elements such as calcium, chlorides, magnesium, sulphates, iron, nitrates, manganese, carbonates, sodium and silica.

As the water in your RO systems leaves the RO membrane, the remaining dissolved solids are removed from the production water as they pass through your DI resin. As each ion passes through the DI resin, it is attracted to and attaches itself to either a positively or negatively charged bead, resulting in 100% pure, reef grade water with a 0 TDS reading.

DI resin is crucial and is used in all Reef Pure RO systems as it is the only way to ensure that you are getting 0 TDS production water for use in your aquarium. With a >98% rejection rate from your RO membrane, you will be left with at least 1% of the contaminants remaining in your water. Using this water without utilising a final stage of DI resin will mean that there is an unknown list of contaminants entering your aquarium. These could include heavy metals which are toxic to invertebrates of all kinds.

What is TDS (Total Dissolved Salts)?

TDS is a reading which indicates the total dissolved solids (TDS) of a solution, measured in ppm (parts-per-million). The lower the TDS reading, the purer the water and the less dissolved solids it carries. In this case, we are interested in both the TDS value of our tap water and the production water created by our RO systems.

The TDS of your tap water will vary, depending on your state and suburb’s water supply, however, the only TDS level acceptable for a marine or reef aquarium is 0 ppm. If your reading is any more than 0 ppm, then you are accepting the fact that your water is contaminated with unknown dissolved solids.

A good quality TDS monitor, like the HM Digital® DM-1 TDS Monitor, will provide a constant TDS reading. This way you can always be sure of the quality of RO/DI water you are producing for use in your aquarium. We supply these monitors with our ‘Essentials+’, ‘Premium’ and ‘Expert’ series systems. We also sell these monitors separately.

Do I need a system with a booster pump and why?

Our ‘Expert’ systems include a booster pump as standard, however, we also sell booster pumps separately as an upgrade option for any of our systems. Whether you need one or not will depend on a couple of things.

Booster pumps dramatically increase the flow rates of each of their respective systems and the amount of production water they produce. This means that you won’t have to wait as long to make up 20 litres of RO/DI water.

A booster pump will also drastically increase the rejection rate of your RO membrane, meaning the quality of water before reaching the DI resin is better, increasing the life of your DI resin.

TFC RO membranes are most efficient and work optimally when provided a tap water pressure of 90 PSI. Most home water supplies do not come close to this. The average residential water supply in Australia is 72 PSI. By increasing your pressure to 90+ PSI, your RO membrane rejection rate will improve, saving you money by increasing the time between DI resin replacement.

How often will I need to replace my pre-filter cartridges?

The frequency in which you will need to replace your system’s pre-filters is greatly dependent on a number of things. The main things to consider are the quality of your tap water before filtration, the amount of sediment it carries, the levels of chlorine/chloramines and the volume of water you are filtering. Obviously, the more water you are filtering, the sooner you are likely to need to look at replacing your filters.

A good rule of thumb is to change them every 6 months.This will ensure that your carbon blocks are removing all organic contaminants, toxins and disinfectants such as chlorine and chloramines. Not only will this guarantee you are getting the best quality water out of your system but it will also ensure that your RO membrane is protected, increasing its longevity.

Should I expect 0 TDS from my system?

Absolutely! If you have selected the correct system for your home’s tap water, then you should definitely be achieving a 0 TDS reading from your Reef Pure RO system’s product water. If you are getting anything higher than 0 ppm, then the product water is not reef safe and will cause issues in your aquarium.

A reading of anything other than 0ppm can indicate that it may be time to replace your RO membrane or DI resin or there is a fault somewhere in the system.

How important is a TDS monitor, do I really need one?

A TDS monitor, like the HM Digital® DM-1 TDS Monitor, is a vital part of any RO/DI system and if you don’t have one, we recommend adding one.

It plays a major role in ensuring that your system is performing at it’s best and continues to do so. It will alert you to when it is time to replace RO membranes and DI resin cartridges as well as ensure that the production water you are placing into your RO storage container is of the best quality possible with a 0 ppm TDS reading. Without a monitor, it is all just guesswork.

Why doesnt my DI resin stage fill with water?

The DI resin cartridge when inserted correctly draws water up from the bottom of the housing. This causes air to become trapped within the housing around the outside of the cartridge. This will not cause any issue and is an indicator that the cartridge seals are working properly.

Where are Reef Pure RO systems built?

All parts used in our systems, have been sourced from only reputable suppliers and manufacturers. By doing this, we can ensure that the systems we are providing are of the highest quality possible without trying to make them the cheapest.

All of our systems are constructed right here in Brisbane, using parts that we have carefully selected from both international and local suppliers. All of our systems and parts are 100% NSF certified to ensure you receive a product which reaches internationally recognised standards.

What maintenance is required and how often?

We strongly recommend changing your system’s pre-filters every 6 months. This will ensure that your RO membrane is always protected from any chlorine and chloramines, which will permanently damage the membrane by oxidising its surface.

You will also need to refill your DI resin cartridges as they are depleted. You will know when this has occurred as the resin will change from blue to gold. If you have a TDS meter installed on your system, you will also begin reading a higher than 0 ppm TDS reading.

When changing out pre-filters, refilling DI resin canisters or swapping over filter housings, we highly recommend using Reef Pure RO Systems Silicone O-Ring Compound & Valve Lubricant or DOW Molykote 111 Compound®. Both are a general purpose O-ring and valve lubricant and will greatly extend the life of the O-rings on your filter housings. We sell this product in economical, single-use containers for this purpose.

Lastly, to extend the longevity of your RO membrane, it is a good idea to install an optional flush kit. We sell these kits separately and they can be installed on any of our RO/DI systems.

Installing one of these kits and allowing your system to flush the membrane for 5 mins before and after each use is good practice and will also dramatically extend the life of your RO membrane.

What is the difference between RO and RO/DI?

Put simply, RO is purely a water filtration system which consists of sediment filters, carbon filters and lastly RO membranes. This process alone can produce water with a low TDS value but not usually a 0 TDS value. This means that RO water alone is unsuitable for our marine and reef aquariums.

This is where DI (Deionisation) resin comes in. The product water produced by our RO systems will still contain some dissolved solids. This is because the RO membranes are only capable of a >98% rejection rate when working at their optimum level. This means that approximately <2% of the contaminants in your tap water will remain and enter your aquarium unless DI resin is utilised.

This is why all of our systems include at least a single stage of DI resin. The DI resin stage is responsible for polishing the remaining TDS from your RO production water, making it perfectly suitable for use when mixing fresh saltwater or topping off the evaporation within your aquarium.

Which RO membranes are used in Reef Pure RO systems?

All of our systems include high-quality Pure-Pro TFC membranes that are made in the USA. There are cheaper membranes on the market but none offer the same quality and reliability.

Which Reef Pure RO system is right for me?

This depends largely on where in Australia you live, the quality of your tap water and the chemicals that are added by your water supplier.

We also have a comparison table for our systems which can help you understand the major differences between each system. You can find our comparison table under the ‘Information’ menu on our website and also on the product information page of each system.

Here in Australia, tap water quality and TDS readings can vary dramatically between suburbs, not to mention states. Our research has shown that parts of Brisbane can range from TDS readings of 56 ppm, anywhere up to 320 ppm.

This means that if your tap water has a beginning TDS reading of 56 ppm, then the product water out of your RO membrane, which provides an average of 98% rejection, will likely be in the vicinity of <2 ppm. A single stage of DI (deionisation) resin will be sufficient to remove this remaining TDS.

However, if your tap water has a beginning TDS reading of 320 ppm, then you will be left with a TDS reading of approximately 6.4 ppm after your RO membrane. A single DI resin stage will not likely be enough to remove all of this.

How often will I need to replace my RO membrane?

An RO membrane will last anywhere between 2-3 years and this will vary depending on a number of factors. Firstly, the quality of tap water being filtered will have an impact on the lifespan of your membrane. The more contaminants that your membrane needs to remove, the shorter it’s lifespan. The volume of water that is being filtered by your membrane will also make a big difference in how often you will need to look at replacing the membrane.

Also, replacing your pre-filters every 6 months will ensure that your RO membrane is always protected. Your carbon blocks will remove chlorine and chloramines from your tap water before it reaches your RO membrane. Poorly maintained pre-filters will allow chlorine and chloramines to reach your RO membrane. As chlorine is an oxidiser, it will cause permanent damage to your RO membranes.

We also sell optional RO membrane flushing kits. Allowing your system to flush the membrane for 5 mins before each use is good practice and will also dramatically extend the life of your RO membrane.

If you have a TDS monitor like the HM Digital® DM-1 TDS Monitor installed on your system, it is easy to check the performance of your membrane. When the TDS reading increases beyond what is normal, you will know that it is time to replace the RO membrane.

What are the benefits of having a 6 Stage system with 2 DI resin stages?

All Reef Pure RO Systems include a minimum of 1 stage of DI (deionisation) resin. This stage is crucial to the system, removing any contaminants that have passed through the RO membrane. Without this stage, harmful elements would enter your aquarium having very negative effects on your livestock.

Our 6 Stage systems offer 2 DI resin stages. These systems are for the serious reefer.

If you are not sure what is in your water or it contains excessive amounts of TDS, then the 6 Stage systems are for you. They are designed to treat any water your home may have effectively, making sure any stubborn, hard to remove contaminants like chloramines, phosphates, nitrates and silicates are totally removed.

Another added benefit of having an additional DI resin stage is that you can rotate the cartridges as the first DI resin stage changes colour from blue to gold, indicating that it has been depleted. This way you will always be sure that you have a fresh cartridge of unused DI resin in operation.

What is the difference between chlorine and chloramine and why does it matter?

Chlorine is always found in Australian tap water, regardless of the state that you live in. There are varying levels found in different water supplies around the country, however, any level is toxic to marine life and must be removed. Chlorine is commonly used because it’s quickly added, effective as a disinfectant and is the least expensive method of water disinfection. Chlorine is quicker acting but is used up faster as it reacts with contaminants in the water and is difficult to keep in solution.

In recent years, we have seen chloramines introduced into local water supplies. Chloramines react more slowly than chlorine, but they stay active for longer periods of time in solution, making it a better choice for use in water supplies that are more likely to contain harmful bacteria. Many states within Australia now use chloramines in addition to chlorine to ensure that our water supply is free of harmful bacteria. Whilst the use of chloramines in tap water for human consumption is questionable, there is no question about its toxicity to the life in our aquariums.

Chloramines are formed when chlorine is combined with a small amount of ammonia. As both chlorine and ammonia are highly toxic to all marine fish and invertebrates, chloramines are even more dangerous than chlorine and more difficult to remove.