What is RO Water and Why Should You Use it in Your Fish Tank?

Any fledgling fish tank owner knows how important it is to get the pH and mineral levels in their water just right. Make one small mistake and your new pets will be belly up before you even get a chance to name them.

Even when you follow all the recommendations to a tee, keeping your fish healthy (and alive) can still be a challenge.

One option that many diehard aquarium enthusiasts are turning to is the use of RO or reverse osmosis water.

Today we’ll take a look at what RO water is, and how it can improve the life of your aquatic friends.

Read on to find out what all the hype is about.

What’s Wrong With Plain Old Tap Water?

Tap water differs greatly from one region to the next. You may have hard water with lots of minerals, or soft water with only sodium ions.

In general, tap water in the US contains a variety of minerals, such as magnesium, calcium, potassium and copper. These are minerals our body actually needs to stay healthy, though they aren’t found in large enough quantities in our water to sustain us.

Although copper in the right doses is something our body needs, too much copper can be dangerous. If you have high levels of copper in your water, it may be due to corrosion that’s happening in your plumbing.

Other contaminants, such as pesticides, chlorine or lead may also find their way into your drinking water and can be extremely harmful. If you are unsure about the safety of your tap water, the Environmental Working Group has created a helpful database where you can check what’s been found in your city’s drinking water.

Needless to say, all of these minerals and chemicals can be toxic to fish, who have much different health requirements than us humans.

Also, high levels of nitrates and phosphates can trigger an algae eruption that can quickly get out of control. Before you know it, your tank is so green that you can’t even see your fish swimming around in there.

That’s where reverse osmosis water comes in.

What is Reverse Osmosis Water?

RO water is water that has been treated, or purified, through the process of reverse osmosis. It may sound complicated, but the process is actually quite simple.

You might remember learning about osmosis in your high school biology class. It’s the principle that describes how water will move from a less concentrated solution to a more concentrated one if there is a semipermeable membrane separating them.

A semipermeable membrane is something that allows certain molecules to pass but not others.

Osmosis occurs naturally and is essential to life on this planet. Our bodies use osmosis when water in our blood is absorbed by our kidneys, and the roots of plants use osmosis to absorb water from the soil. Osmosis is happening all around us.

So the process of reverse osmosis uses pressure to do that same thing in reverse.

Water is forced through a semipermeable membrane, removing up to 99% of any dissolved sodium ions, minerals, bacteria or other impurities in your water.

It is an extremely effective process and has been used for decades.

Why RO Water is a Healthy Choice for Your Aquarium

Different fish require different types of water. The first obvious differentiation is saltwater vs. freshwater fish, but things get much more complicated beyond that.

Neutral water has a pH of 7.0. That number drops as the water gets more acidic, and increases as it gets more alkaline.

Think about the varied ecosystems where fish live: rivers, streams, lakes, ponds, and oceans. All of those places are going to vary in pH and mineral composition.

When it comes to aquatic life, it’s important to get as close as you can to a fish’s natural environment.

Using reverse osmosis water in your fish tank essentially lets you start from scratch. It strips your water of any and all minerals and impurities, which can then be treated to best suit your fish’s needs.

RO water generally has a pH of between 5.0 and 6.0, so you will want to research what pH your fish need and adjust accordingly. Saltwater fish generally need a pH of 8.0 or higher, while freshwater fish do well somewhere in the 5.5 to 7.5 range.

It’s important to mention that just like humans, fish do require certain levels of minerals in their water. So just putting RO water straight into your tank is not going to cut it, and can actually be damaging to your fish.

Your pet shop will be able to recommend a prepared mixture of salt, calcium and other minerals that you can add to your tank to get those mineral levels just right. These are known as marine salt mixes, and they’ll help get your pH to the right level and stabilize it.

Your fish will thank you.

Are There Any Drawbacks?

One aspect of using reverse osmosis water that some fish owners find challenging is the amount of time it takes to complete the filtration process.

Because pressure is needed to treat the water, there is much more wastewater produced during the process than purified water. You usually get one part filtered water to every five parts wastewater.

That doesn’t mean you need to pour the waste water down the drain; it can still be used for things like watering the plants or mopping the floors.

Another drawback is that the cost of reverse osmosis filtration systems can also be prohibitive.

It is important to do your research and find out what system will be the best fit for your aquarium. Different filters use different types of membranes, and some remove more minerals than others. For example, High Silicate (Hi-S) membranes remove 97.5-99% of dissolved solids, while Cellulose Tri-Acetate (CTA) membranes only remove 88-94%.

There are many options out there, and you should be able to find something that works with your budget. You just want to make sure you’re purchasing a reputable product that’s going to last.

Maintenance is Simple

If you find a reverse osmosis filtration system that is a good fit for your tank, it shouldn’t require a great deal of maintenance. Make sure you flush out the system before installing it, and then you should be good to go.

The membrane is very durable and should not need replacing for several years. Still, it’s important to find out what the cost of a replacement membrane will be when purchasing an RO filtration system.

The membrane will last even longer if you flush out the system periodically using a flush kit. You can also use a TDS meter, which measures the total dissolved solids, to keep track of how well your membrane is working.

Most RO filtration units also include carbon and sediment filters which will need to be replaced every six months or so. But if you get them from a reputable dealer at a fair price, they shouldn’t break the bank.

When you see that your filters are starting to discolor, that’s a hint that it’s time to change them, but your RO system’s manufacturer should provide detailed information about how often to replace them.

One important tip for keeping your RO filtration system in good working order is to avoid filtering water that is too hot, as that can shorten the lifespan of the unit. The ideal temperature is usually between 70 and 77 degrees.

You can use RO water to top off any evaporated water from your tank. That way you won’t always be replacing large quantities of water, but simply keeping on top of it as needed.

The low demands of maintaining your RO filtration system will be well worth it to know that your fish are living in impurity-free water.

Take Things Slow

One thing that’s important to remember is that you don’t want to make any sudden changes to your tank.

Make adjustments gradually, allowing for your fish to adapt to their new surroundings. Don’t rush into anything.

For example, when introducing reverse osmosis water to your tank for the first time, you don’t want to replace all of the water at once. Start by introducing it gradually.

The good folks at your local pet store will be able to give you advice about this process, depending upon what type of fish and plant life you have in your tank.

Healthy for Your Fish, Healthy for You

Why should your fish be the only ones to reap the benefit of clean, pure water?

Some aquarium owners argue that drinking reverse osmosis water that has been re-mineralized can be one of the healthiest forms of drinking water out there.

So you might want to consider investing in a reverse osmosis filtration system that you can use for both yourself and your fish tank. Many RO units attach right onto your faucet, so producing healthy, filtered water is a breeze.

To learn more about what RO water is and why it can be a wonderful alternative to untreated tap water, visit our blog.

And good luck with those fish!

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