People have been using RO, or Reverse Osmosis, water for their aquariums for a long time. However, recently, it’s use has started becoming almost trendy. Should you be using RO water in your tank? How do you prepare it? We will review all, below.
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Understanding Reverse Osmosis
Some people think that RO is a thing, but in reality, it’s a process. Basically, it is the process of taking a strong solution and diluting it by allowing the molecules of a weak solution to pass through a membrane.
This membrane is a semi-permeable one, meaning that some molecules, in this case, water, can pass through. However, if something is too big, it cannot pass.
In reverse osmosis, the water is forced to go through a semi-permeable membrane. The water on one side of the membrane is extremely pure. The water left is referred to as “wastewater”, and it contains all of the contaminants.
Why Use RO Water in an Aquarium?
There are a number of reasons you might want to use RO water in a fish tank. First, of course, is because the water is really pure. This makes it very safe for the fish and other animals in the tank.
It also has a neutral pH, which means you can provide a lower pH in the water where your fish will live.
Finally, it also is free of chemicals like chlorine, nitrate, and heavy metals.
Is RO Water Necessary?
You might be wondering if it is necessary to use RO water. The answer is, ‘No’. If you live in a developed country, like the US, Canada, or UK, amongst many others, the water from the tap is perfectly fine to use, as long as you condition it chemically.
It is understandable that you might not want to use RO water. It is expensive, and once you start using it in an aquarium, it’s quite difficult to go back.
Using RO Water in an Aquarium
If you want to use RO water in your tank, you have to prepare it. Remember, because it’s pure, it has no alkalinity, no hardness, and none of the elements from natural water that your fish might need to survive.
All fish require slightly hard water to survive, and in order to keep the pH level, you need to ensure a bit of alkalinity in the tank. So, in regard to RO water, you must add some things into it.
“Easy” RO Water
One way to prepare RO water for your tank is to mix tap water and RO water together until you create the perfect mix. You might think it is simple to reduce pH in this way by mixing half tap water and half RO water. The pH of the tap water would go down by half…but that’s not true.
Actually getting the pH you want is a bit more complicated. We also need to consider the alkalinity. If the water has a high alkalinity, mixing it with RO water may not even have an effect.
So, it’s best to do a bit of trial and error to determine what works. Then, just repeat this each time you prepare your water.
“Hard” RO Water
The other option you have is to prepare RO water the “hard” way, meaning there is more to it than simply mixing tap water and RO water together. In this method of preparation, you are going to be adding the actual minerals back in.
This must be done carefully, and the best way to go about it is to use commercial chemical products made specifically for people like you who want to do this.
There are many products you can use for re-mineralization of your RO water, and some of them are even formulated for certain types of fish. You can also find chemicals that you can add for community tanks that have a number of different fish.
You have to use caution when using these products. Some of them only work on setting the pH correctly, but remember, you have to be aware of the alkalinity, too. There are other products that do both.
When preparing the RO water for a fish tank, you should generally add chemicals to adjust the pH first. It’s best to do with in the tank before adding fish. You should add the chemicals and run the pump or air stone for around 24 hours.
Next, you have to adjust the alkalinity. Remember, the alkalinity can affect the pH, so make sure you are checking it again before adding your fish. It should be perfect!
Considerations When Using RO Water
Before we close, we need to make sure you understand all there is to know about using RO water.
First, when you switch from conventional tap water to RO and you have fish in a tank, you must do it gradually. Doing this too quickly can be deadly to your fish.
It doesn’t matter if you are putting the fish in a new tank with RO water, or you are changing an existing tank from a “tap” tank to RO tank, you must do it a bit at a time.
Remember, once you make a change like this, you must do it every time you change the water. It will likely kill your fish to go back to straight tap water. So, you always have to make sure that you have prepared RO water on hand as well as any chemicals you might need.
The mix must also be consistent. You can’t have a pH at one level, and then drastically adjust it in the next water change. Eventually, you will know exactly how to mix the water to get results, but as you are learning this, you have to be very careful, and measure everything.
One of the biggest setbacks of using RO water is that it is expensive. It is also quite time-consuming, and it requires you to be extremely accurate in your measurements. You really need to be dedicated if this is something you want to do.
You also must decide if you want to purchase your RO water or if you want to buy a device that can do it for you. Both methods have pros and cons, so explore all of it before you make a choice.
Keep in mind that if you make your own RO water, that the cost of the unit can be high, and you have to purchase a monitor, so you know what is in the water you are producing. You also need safe storage containers and space to store your water.
Additionally, you have to regularly buy new RO membranes and filter elements, and you may need to hire a plumber to install the unit for you. There is also the fact that you will have to consider a much higher water bill than you might be used to.
It generally takes a lot more water than you think in order to produce the amount of RO that you need. The rest is simply wastewater that you are going to pay for and ultimately send down the drain.
Finally, speaking of this, depending on where you live, you also may need to let your water company know that you are installing an RO unit, and you may be charged extra for drainage.