What is RODI water and why do I need it?
What is RO and RO/DI water?
RO or Reverse Osmosis water is the product of forcing water through a semi-permeable membrane which ONLY water can flow through and expeling the "brine" water that cannot pass through. DI or De-Ionised water has been passed through a bed of special resin which absorbs the Ions that the RO membrane couldnt reject These processes produces water that is more pure than water found anywhere in nature, so pure that it quickly absorbs carbon dioxide from the atmosphere and becomes mildly acidic if left exposed to air!
Types of purification system
Ultra Filtration Systems
Most of these systems are developed by companies with their own interests and use specific filters that are brand specific and cant be interchanged or replaced with generic brands, however they all generally work the same, consisting of a series of filters ranging from cloth sediment filters through to carbon, chemical resins and brand specific "specialised" filters all of which remove impurities from the water. By using filters that will remove impurities less than 0.45 micron you can even remove bacteria, parasites and pathogens and produce a very clean, very close to "pure" water. These systems are generally used for drinking water but if filter cartridge changes were kept up to schedule, this could get quite costly, then they may be suitable for use in marine aquaria. I would be testing for total dissolved solids and conductivity/resistivity before use to ensure the filters are still doing their job.
Reverse Osmosis Systems
There are two main types of RO purification systems namely Automatic and Manual. As the name implies the automatic units are more convenient but more expensive and complex than the manual counter parts. For most nano tanks a manual system will be sufficient but I would recommend an automatic system for anyone using large amounts of water for water changes and top ups. It will become a tedious task making up large drums of water as you will have to monitor the drum for a long time to prevent it overflowing.
Manual RO Systems
These systems are extremely simple as far as RO systems go... They generally consist of 1 or 2 prefilters namely a sediment filter usually 5 - 10 micron and a carbon filter (specifically to remove chlorine as it can damage the membrane) and then the membrane its self. Some systems will have a carbon post filter also but not in all cases. They have 3 pipes to connect, the first is the inlet which is where your domestic drinking water is connected to, then there is the waste outlet from the membrane housing and finally the product water outlet. A lot of these systems are sold as portable, benchtop or caravan systems (although these units generally have "mineraliser" post filters more on that later). The major downfall with these units is that they are very slow to produce water and have to be monitored and shut off manually to avoid overflows.
Automatic RO Systems
Automatic shut off RO systems are very much the same in their overall function but with the addition of a few simple little parts it becomes a much more user friendly system. First of all you need a storage vessel, either an open/vented vessel with a float valve or solenoid or a sealed pressure vessel with a preset or adjustable back pressure, then when the vessel is full then you need something to shut the inlet water off so that it doesnt just keep running water to the waste line, thats where the "Automatic Shut Off" valve come into play, its a very simple valve that when then outlet water pressure reaches a specific point in relation to the inlet water pressure it shuts off the water to the inlet. This allows you to have RO water stored under pressure ready to use on tap as opposed to waiting for it to drip into a container!
De-Ionising Resin Filters
These are simply another filter that water passes through. They are fillled with a resin that absorbs Ions from the water producing a very pure water when combined with an ultra filtration system or RO system.
This link from wikipedia goes into more technical detail about these filtration systems.
Plumbing
Any plumbing installation performed in Australia needs to be carried out by a qualified plumber. Now that the disclaimer is out of the way... If you are capable of connecting a hose to a garden tap then there is not much else to know when it comes to installing a water filter. With the ranges of clever fittings available these days it really is easy! Always talk to your filter supplier about plumbing options when looking to purchase a filter.
The most important consideration when installing a water purification is to follow manufacturers/suppliers recommendations regarding water pressure limits. The installation of a pressure limiting valve on the inlet of the water filter will be required in most cases, if you are unsure of your water supply pressure you can either test it with a pressure guage or the cheaper option (if you dont own a suitable guage) would be to just install a suitable pressure limiting valve just to be sure.
Many RO systems are designed to be connected to the outlet of your kitchen taps. I wouldnt recommend this as it puts pressure on parts not designed to be under pressure, however lots of people use these and dont have a problem so take that advice how you will. I would recommend having a plumber install an isolation valve under you kitchen sink or in your laundry if you do not have a tap spare and are not capable of installing one yourself. All RO systems need a connection to a drain for waste water so consideration need to be made for this when planning your installation.
Why do I need RO/DI water?
Using pure water is important in a reef aquarium moreso than a FOWLR tank but I would reccomend using RO or at the very least "ultra purified water" in all situations. You really dont know what is in your tap water... Sure its clean enough to drink but it contains trace amount of metals (including copper), chlorine and chloramine, phosphates and many other compounds in barely tracable amounts. When in a closed system, even trace amounts of chemical compounds can build up to toxic levels when contaminated water is used to top up evaporation losses. RODI water is stripped of all contamination and when used to top up evaporation losses does not introduce anything other than water to the tank.
How long will my system last?
This depends on several factors including the quality of incoming water, the types/grades of filter cartridges used, the amount of water produced and in the case of RO and DI systems even ambient temperatures can affect the life span of your system.
Sediment filters should be changed at least every 6 months and should NEVER be left more than 12 months as they can harbour bacteria and become a potential health hazard. Carbon filters should be changed when any detectable level of chlorine is present after the filter or at intervals not exceding 6 months. Semi permeable membranes from RO systems will last 2 - 3 years and should be sterilized every 12 months to ensure there is not harmful bacteria breeding in it, if you are unsure about cleaning the membrane you should speak to the manufacturer/supplier or a water purification specialist in your area. DI resin filters life depends very much on the amount of water produced and the quality of the incoming water. Testing the product water for conductivity/resistivity will tellyou when the resin needs changing, without testing I would recommend replacing the resin every 3 - 6 months. Keep in mind that heat will quickly degrade DI resins making them useless. If you have spare resin filters they should be kept in the fridge or at least in a cool place.
Is tap water as evil as they say?
Yes and No is the simple answer... Confused? There is no real answer to this, I know from personal experience in the plumbing trade that water quality in reticulated systems can vary quite significantly from one house to the next, from one day to the next and even from one hour to the next! The real problem with tap water is that you really have no idea whats in it. Even if you had it tested in a lab and it came back with no trace of anything harmful/undesireable to a marine aquarium, the next time you fill up your bucket its not going to be the same water you had tested! You just dont know whats in it... Whats the answer? Take everything out of the water and start with a clean slate!
Can I use rain water?
Once again there is no simple answer to this question, rain water quality can vary depending on your geographical proximity to airbourne pollutants. Water falling in the middle of the country is less likely to contain pollutants than rain which falls in the middle of the city/suburbs. Having said that the main reason for contaminated rain water comes from where it lands and is stored. If you have an old unglazed tiled roof with old rusted gutters full of bird dropping and leaf litter, running into galvanised steel downpipes into an old rainwater tank I would seriously think twice about using the water. If you have a nice clean roof and guter system with plastic downpipes and a plastic rainwater tank its probably not so bad but I would still be wary of the water quality and diligent with testing the water first, and still using a filter for sediment and a carbon filter for any residual chemical from the roof, gutters, tanks or pipework.
Can I drink RO/DI water?
This is a really tricky question... There is a debate among the health fraternity as to the health effects of drinking ultra purified water. The argument is that due to the chemical instability of the ultra pure water it will absorb minerals from your body and carry them out through your urine stream, resulting in mineral deficiencies.
The following links describe some of the possible effects of drinking ultra pure water so you can make up your own mind on the subject.
World Health Organization
Wikipedia
Personally I drink my RO (not DI) water that has been treated through a mineraliser filter, which as its name implies adds minerals to the water. This is the best quality drinking water I have ever tasted
RO or Reverse Osmosis water is the product of forcing water through a semi-permeable membrane which ONLY water can flow through and expeling the "brine" water that cannot pass through. DI or De-Ionised water has been passed through a bed of special resin which absorbs the Ions that the RO membrane couldnt reject These processes produces water that is more pure than water found anywhere in nature, so pure that it quickly absorbs carbon dioxide from the atmosphere and becomes mildly acidic if left exposed to air!
Types of purification system
Ultra Filtration Systems
Most of these systems are developed by companies with their own interests and use specific filters that are brand specific and cant be interchanged or replaced with generic brands, however they all generally work the same, consisting of a series of filters ranging from cloth sediment filters through to carbon, chemical resins and brand specific "specialised" filters all of which remove impurities from the water. By using filters that will remove impurities less than 0.45 micron you can even remove bacteria, parasites and pathogens and produce a very clean, very close to "pure" water. These systems are generally used for drinking water but if filter cartridge changes were kept up to schedule, this could get quite costly, then they may be suitable for use in marine aquaria. I would be testing for total dissolved solids and conductivity/resistivity before use to ensure the filters are still doing their job.
Reverse Osmosis Systems
There are two main types of RO purification systems namely Automatic and Manual. As the name implies the automatic units are more convenient but more expensive and complex than the manual counter parts. For most nano tanks a manual system will be sufficient but I would recommend an automatic system for anyone using large amounts of water for water changes and top ups. It will become a tedious task making up large drums of water as you will have to monitor the drum for a long time to prevent it overflowing.
Manual RO Systems
These systems are extremely simple as far as RO systems go... They generally consist of 1 or 2 prefilters namely a sediment filter usually 5 - 10 micron and a carbon filter (specifically to remove chlorine as it can damage the membrane) and then the membrane its self. Some systems will have a carbon post filter also but not in all cases. They have 3 pipes to connect, the first is the inlet which is where your domestic drinking water is connected to, then there is the waste outlet from the membrane housing and finally the product water outlet. A lot of these systems are sold as portable, benchtop or caravan systems (although these units generally have "mineraliser" post filters more on that later). The major downfall with these units is that they are very slow to produce water and have to be monitored and shut off manually to avoid overflows.
Automatic RO Systems
Automatic shut off RO systems are very much the same in their overall function but with the addition of a few simple little parts it becomes a much more user friendly system. First of all you need a storage vessel, either an open/vented vessel with a float valve or solenoid or a sealed pressure vessel with a preset or adjustable back pressure, then when the vessel is full then you need something to shut the inlet water off so that it doesnt just keep running water to the waste line, thats where the "Automatic Shut Off" valve come into play, its a very simple valve that when then outlet water pressure reaches a specific point in relation to the inlet water pressure it shuts off the water to the inlet. This allows you to have RO water stored under pressure ready to use on tap as opposed to waiting for it to drip into a container!
De-Ionising Resin Filters
These are simply another filter that water passes through. They are fillled with a resin that absorbs Ions from the water producing a very pure water when combined with an ultra filtration system or RO system.
This link from wikipedia goes into more technical detail about these filtration systems.
Plumbing
Any plumbing installation performed in Australia needs to be carried out by a qualified plumber. Now that the disclaimer is out of the way... If you are capable of connecting a hose to a garden tap then there is not much else to know when it comes to installing a water filter. With the ranges of clever fittings available these days it really is easy! Always talk to your filter supplier about plumbing options when looking to purchase a filter.
The most important consideration when installing a water purification is to follow manufacturers/suppliers recommendations regarding water pressure limits. The installation of a pressure limiting valve on the inlet of the water filter will be required in most cases, if you are unsure of your water supply pressure you can either test it with a pressure guage or the cheaper option (if you dont own a suitable guage) would be to just install a suitable pressure limiting valve just to be sure.
Many RO systems are designed to be connected to the outlet of your kitchen taps. I wouldnt recommend this as it puts pressure on parts not designed to be under pressure, however lots of people use these and dont have a problem so take that advice how you will. I would recommend having a plumber install an isolation valve under you kitchen sink or in your laundry if you do not have a tap spare and are not capable of installing one yourself. All RO systems need a connection to a drain for waste water so consideration need to be made for this when planning your installation.
Why do I need RO/DI water?
Using pure water is important in a reef aquarium moreso than a FOWLR tank but I would reccomend using RO or at the very least "ultra purified water" in all situations. You really dont know what is in your tap water... Sure its clean enough to drink but it contains trace amount of metals (including copper), chlorine and chloramine, phosphates and many other compounds in barely tracable amounts. When in a closed system, even trace amounts of chemical compounds can build up to toxic levels when contaminated water is used to top up evaporation losses. RODI water is stripped of all contamination and when used to top up evaporation losses does not introduce anything other than water to the tank.
How long will my system last?
This depends on several factors including the quality of incoming water, the types/grades of filter cartridges used, the amount of water produced and in the case of RO and DI systems even ambient temperatures can affect the life span of your system.
Sediment filters should be changed at least every 6 months and should NEVER be left more than 12 months as they can harbour bacteria and become a potential health hazard. Carbon filters should be changed when any detectable level of chlorine is present after the filter or at intervals not exceding 6 months. Semi permeable membranes from RO systems will last 2 - 3 years and should be sterilized every 12 months to ensure there is not harmful bacteria breeding in it, if you are unsure about cleaning the membrane you should speak to the manufacturer/supplier or a water purification specialist in your area. DI resin filters life depends very much on the amount of water produced and the quality of the incoming water. Testing the product water for conductivity/resistivity will tellyou when the resin needs changing, without testing I would recommend replacing the resin every 3 - 6 months. Keep in mind that heat will quickly degrade DI resins making them useless. If you have spare resin filters they should be kept in the fridge or at least in a cool place.
Is tap water as evil as they say?
Yes and No is the simple answer... Confused? There is no real answer to this, I know from personal experience in the plumbing trade that water quality in reticulated systems can vary quite significantly from one house to the next, from one day to the next and even from one hour to the next! The real problem with tap water is that you really have no idea whats in it. Even if you had it tested in a lab and it came back with no trace of anything harmful/undesireable to a marine aquarium, the next time you fill up your bucket its not going to be the same water you had tested! You just dont know whats in it... Whats the answer? Take everything out of the water and start with a clean slate!
Can I use rain water?
Once again there is no simple answer to this question, rain water quality can vary depending on your geographical proximity to airbourne pollutants. Water falling in the middle of the country is less likely to contain pollutants than rain which falls in the middle of the city/suburbs. Having said that the main reason for contaminated rain water comes from where it lands and is stored. If you have an old unglazed tiled roof with old rusted gutters full of bird dropping and leaf litter, running into galvanised steel downpipes into an old rainwater tank I would seriously think twice about using the water. If you have a nice clean roof and guter system with plastic downpipes and a plastic rainwater tank its probably not so bad but I would still be wary of the water quality and diligent with testing the water first, and still using a filter for sediment and a carbon filter for any residual chemical from the roof, gutters, tanks or pipework.
Can I drink RO/DI water?
This is a really tricky question... There is a debate among the health fraternity as to the health effects of drinking ultra purified water. The argument is that due to the chemical instability of the ultra pure water it will absorb minerals from your body and carry them out through your urine stream, resulting in mineral deficiencies.
The following links describe some of the possible effects of drinking ultra pure water so you can make up your own mind on the subject.
World Health Organization
Wikipedia
Personally I drink my RO (not DI) water that has been treated through a mineraliser filter, which as its name implies adds minerals to the water. This is the best quality drinking water I have ever tasted
