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Everything you need to know about Reverse Osmosis for aquatic use

How does reverse osmosis work?

Reverse osmosis uses the mains water pressure to force tap water through a semi permeable membrane. The water is directed across the membrane and passed through the membrane walls. The water that passes through the membrane will not bring the larger impurities with it. The impurities that remain pass into the drain this is how the membrane stays clean.

Why should I choose a Reverse Osmosis Unit?

Reverse Osmosis units use a Thin Film Membrane called a TFC and these will remove between 92 – 98% of all the Total Dissolved Solids in tap water. Some of these include: Bacteria, Chlorine, Copper, Fluoride, Iron, Lead, Manganese, Phosphate, Potassium, Sodium, Sulphate and Zinc. Tap water contains elements such as Nitrates and Phosphates which can contribute to undesirable algae build up. Units an RO unit will help minimize algae growth and aquarium maintenance

What is Total Dissolved Solids?

It is the total amount of suspended solids in your tap water called TDS. If you were to take a litre of water and boil it in a pan until the water was all gone and then measure all of the residue left behind this would give you the measurement of milligrams per litre (Mg/L) of impurities. Parts per million (PPM) is the same measurement.

Do you need electricity to operate an RO unit?

No, an Aquatic RO System runs on the water pressure from the households plumbing.

Why is the TDS reading higher than zero for my filtered water?

If a TDS reading is higher than desired, it could be that the membrane and cartridges need to be replaced. Water first passes through the sediment and carbon cartridges, then through the membrane and lastly through the mixed bed resin cartridge (if on RO unit). The membrane removes the majority of TDS from the water and the resin cartridge removes the remaining. Replacement of the membrane and resin cartridges will usually minimize TDS. If water is allowed to bypass the cartridges or membranes, unfiltered water may be passing through the RO/DI System. Ensure that all cartridges are placed properly in the RO/DI System and that the seals are tight.

Does the Aquatic Life RO/DI System remove Chlorine and Chloramines?

Yes, the carbon cartridge removes chlorine and chloramines before the water comes in contact with the membrane. If the carbon is no longer active or water is bypassing the cartridge, the chlorinated water will damage the membrane and the water will not be filtered properly.

Can I connect the RO/DI System to the hot water line?

NOT recommended - the elements of a membrane cannot withstand temperatures above 113 degrees Fahrenheit (45 Celsius). Most hot water lines operate above this temperature and should not be connected to a RO/DI System. The optimum water temperature for operating an RO/DI unit is 77 degrees Fahrenheit (25 Celsius).

Do micron sediment and carbon pre-filters remove TDS?

The pre-filters (sediment and carbon) do not normally remove TDS (Total Dissolved Solids). The sediment and carbon cartridges are there for the removal of particulate and chemical matter such as rust, sand and chlorine.

The RO process by itself cannot remove all of the TDS, but passing the water through a DI (mixed bed resin) cartridge after going through the membrane removes any remaining TDS. The DI media lifespan depends on what the TDS feeding it is like. This is why the RO process is recommended before a DI filter. The DI (or Mixed Bed Resin) cartridge is made with anion and cation resins for ion removal.

Is a reverse osmosis unit like a distiller?

Both effectively reduce “dissolved solids” content of water, but the processes are quite different. RO filters water through a very tight semi-permeable membrane. A distiller is like a big tea kettle: it boils water, catches the steam, condenses it, and captures the resulting water. Most impurities are left behind in the boiling chamber. Both distillers and reverse osmosis systems rely heavily on carbon filtration for chemical removal.

But isn't distilled water purer than reverse osmosis water?

Distillers typically remove a few parts per million more of common mineral constituents like sodium. However, distillers don't do a good job with volatile chemicals with a low boiling point. Chloramines, for example, which many cities now use instead of chlorine as a disinfectant, aren't removed well by distillers. Reverse osmosis, with the carbon filters that accompany it, does a very good job with chloramines. Unless volatile chemicals like chlorine are removed by carbon filtration before they enter the distiller, they will be released into the room air or they will end up in the distilled water. But in general, distilled water is very pure, as is reverse osmosis water.

How often do my filters need replacing?

The filters need to be replaced every 6 months and the Membrane every 1-3 years depending on the incoming feed water quality.

What water pressure is needed for the RO system to function?

The RO units require a minimum pressure of 3 bar (40 psi). If you need instructions on how to check your water pressure, please get in touch with us using

What if my water pressure isn’t enough?

Pumps are available on-line to boost mains pressure to work alongside RO units.

Can I install the unit myself or do I need a plumber?

If you are good at DIY you may be able to install the units yourself but we do recommend that a qualified plumber is used.

Do you have a different question? Ask us! Call us on 01704 807600 or using the 'contact us' page.