So you have a brand new aquarium and you can’t wait to move the fish in. But before you introduce your swimming pets to their new tank, you’ll need to get your water perfectly balanced for their health and happiness. Depending on the type, fish won’t do well in water that is too hard, too soft, or that has the wrong pH.
You have several options for aquarium tank water. Just realize whichever you choose, you will need to either treat it in some way or choose a source that has already been treated to your specifications. Sources include: reverse osmosis water, tap water, softened water, bottled water, and de-ionized purified water.
Resist the temptation to use rain water or water collected from a nearby creek. You don’t know which contaminants or pollutants these water sources contain.
Each water source has its pros and cons. Consider which kind works best for your fish.
Reverse Osmosis Water
Reverse osmosis (RO) water has had all its impurities and particulates removed, which leaves a very pure, very soft water. However, super pure water won’t work for your aquarium all on its own. Reverse osmosis water doesn’t have any minerals, and the treatment process has removed its ability to predictably respond to chemical changes. Reverse osmosis water’s pH levels may vary wildly and change fast.
This type of water works best for advanced aquarium owners who know exactly what kind of water they need and how to balance this very pure water to get the exact composition they’re looking for. Beginning aquarium users may want to choose a different type.
If you do want to use reverse osmosis water but want a little more balance, you can mix some RO water with some tap water and check its balance.
Most tap water works well for aquarium use. However, most municipal water plants chlorinate their water, so you’ll need to check which treatments yours has first. If your water is chlorinated, you’ll need to dechlorinate it. The water’s pH, KH, and GH balance and nitrate levels also depend on its location. Test your tap water and adjust as necessary before you put it in the tank.
One benefit of tap water is that it already has trace minerals your fish need to be healthy. However, too high of a mineral content isn’t a good thing, so soften the water as necessary.
If you have a water softener, this water usually works well for aquariums. Softened water is an easy choice because you don’t usually have to do much to it before putting it in the tank. If you plan to use this source of water for an aquarium, then you’ll want to invest in a water softener if you don’t have one already.
While softened water is usually safe to use, double check with your water softener provider first.
Bottled water is not a great choice for aquarium water. It’s expensive, and because the industry is unregulated, it’s impossible to know what parameters the water in the bottle has. If you insist on using bottled water, balance it carefully before use and watch out for erratic chemical changes.
Similar to reverse osmosis water, de-ionized water has been ultra-purified by having its various ions neutralized. Since it’s so pure, de-ionized water has many of the same challenges as reverse osmosis water. This water works best for advanced aquarium users, and you must carefully balance it for correct composition before use. Remember you can mix some de-ionized water with some tap water for a more stable balance.
As a new aquarium owner, your water will dictate your fishes’ health, lifespan, and overall environment. Choose carefully, and contact a local water treatment professional to gain easy access to the type of water you choose.