Which Water Is Best For Aquarium Fish – Best Fish Keeping

Last updated on December 24th, 2022 at 11:04 am

Which Water Is Best For Aquarium Fish

As an aquarium hobbyist, it is your duty to keep your fish healthy and well. Not only do you need to provide them with enough space and a healthy diet, but you also need to ensure that the tank environment meets their needs. 

The most important factor for the health of your fish is the quality of your water. Therefore, it is necessary that you select your water source correctly and condition the water properly. This article will help you solve both problems.            

Tap water

The most common source of tank water for aquarium enthusiasts is simply the tap, the water that flows through your home. It is the easiest source to get water and works very well in most cases. However, the parameters of tap water can vary greatly from place to place. 

You need the tap water pH, gH , kH and nitrate tests in order to understand exactly what tap water emerges from . If your fish’s preferences are drastically different from your tap water settings, you may need to use a different water source.                                          

Always remember to use a chloramine dechlorinate / stripper on tap water if it comes from a municipal water supply, as it has probably been treated with chemicals. These chemicals are designed to make tap water safe for humans, but they can be toxic to fish. 

If you prefer not to treat your tank water with chemicals, it may be enough to let the tap water sit for about 24 hours to allow some of the chlorine to evaporate.                

Spring / bottled water

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A possible alternative to tap water is spring water. Spring water is useful when you need to lower the pH or hardness of your aquarium water. The main disadvantages of spring water are the price and the fact that the mineral content varies considerably from brand to brand. 

The best thing is to buy several different brands, at the beginning and each test pH, kH and gH , before this filter , which adapts to the preferences of your fish. One way to achieve a balance between tap water and spring water is to mix the two, which also reduces costs.

 When using bottled water, make sure it is not distilled (this means all minerals have been removed) and that it has not been treated with any flavor, color or color. ”Other additives.                                                 

Reverse osmosis water

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Another option is reverse osmosis water. Reverse osmosis is the process of applying pressure to a concentrated solution to force it through a membrane. The membrane allows water molecules to pass through but blocks larger molecules, such as minerals and other contaminants. There are different types of membranes for reverse osmosis:         

Cellulose Triacetate (CTA): CTA membranes are made of organic materials and produce less pure water (88% – 94% remove impurities) than the other two membranes. They do not remove chlorine from the water, so you will still have to use a dechlorinator or let the water sit for 24 hours.                 

Thin Film Composite (TFC) – TFC membranes are made from synthetic materials and remove 94% to 98% of contaminants.

High-distance membranes: High-distance membranes are made of synthetic materials and remove between 97.5% and 99% of contaminants. These membranes can remove silicates very well.   

One problem with reverse osmosis water in freshwater aquariums is that it can be too pure – it has too few trace minerals that fish need. So it never makes sense to just use reverse osmosis water. Instead, it must be mixed with tap water in a certain proportion. You will have to experiment with different ratios to determine the parameters of the water you need.         

Another problem with reverse osmosis water is that it contains either kH or gH . This means that it has no buffering capacity and is very flexible. The result can be large fluctuations in the pH and other parameters of the water; this is obviously not good for your fish. 

This is another reason why mixing with tap water can be helpful as the kH and gH of the tap water increase . You can add a business stamp instead , but you need to be careful. If you are trying to use 100% reverse osmosis water and add chemicals / products to fix the problems, you need to carefully monitor all settings to make sure the aquarium is not stuck.                                                

Lake / river / local stream water

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While using water from a local source seems like a good idea, it generally isn’t. It will save you money, but it may charge you in other zones. If you get water from a local source, you don’t know what contaminants the water contains or what mineral content it contains. This can make it very dangerous for your fish. For this reason, the use of local lake / river / stream water in an aquarium is not recommended.                       

Rain water

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Rainwater is similar to lake / river / stream water in that it is not known what kind of pollutants it contains. The air around you may appear clean, but you have no idea what the rainwater has collected along the way. Therefore, rainwater should not be used in an aquarium.      

Water parameters and problems / solutions

pH: pH measures whether the water is basic, acidic or neutral. A pH of zero is the most sour, 14 is the most basic, and 7 is neutral. Most fish prefer a pH between 6.4 and 7.8, but some fish prefer a pH outside this range (African cichlids, for example, prefer a higher pH). 

Although fish prefer certain pH levels, most can easily adapt to a wide range. However, they cannot withstand large fluctuations in pH (large fluctuations from the mean of more than 0.3 over a 24 hour period). Rather than aiming for a particular value, it is more important to maintain a constant pH .                            

For example, if your pH is too high, you can try mixing in some spring water to lower it. If you have large variations in the opinion of pH , this may be because your kH is too low and your water does not have enough buffering capacity. You can measure your kH and then take action to correct for a low kH .                                                                     

● kH – kH measures the concentration of carbonates and bicarbonates in your water. It also shows the buffering capacity of your water. The buffer capacity is the ability of water to neutralize the acid added without significantly changing the pH . 

If your kH is too low (less than 4.5 dH ), problems with large fluctuations in pH can occur. Over time, the nitrates in your aquarium will increase and the pH will decrease. Large buffer capacity to resist this fall and maintains the stability of the pH vertically .                                                                

● gH – gH is the general hardness of the water. It is primarily a measure of the concentration of magnesium and calcium ions in the water. gH is the parameter that determines whether you have “hard” or “soft” water. 

So if you read that your fish prefers fresh water, it means that your fish prefers low gH and not low kH . Like pH, most fish can be adjusted to a wide range of values ​​regardless of your preferences. The biggest exception is the breeding of many species.                                              

If your gH is too low, you can add stones like limestone to the aquarium or use crushed coral as a substrate (or put them in a mesh bag on your filter). These substances also increase your pH. 

If your GH is too high, you can filter through peat, add reverse osmosis / spring water, or use a commercially available water softener (although this is generally not considered safe for many freshwater species because it introduces sodium that many do not tolerate) well).                        

Condition your water

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Some aquarium hobbyists recommend adjusting the exact details of your aquarium water settings to suit the needs of your fish. However, this can be difficult in practice, as the requirements of the fish in the tanks can vary by species and whether they have been wild-caught or raised for trade. 

Perhaps the best option is to adapt your fish to the water configuration of your aquarium. The most important thing you can do is keep the water in your tank clean, keep the water settings stable, and avoid adding too many substances to the water.         

There are many chemical additives on the market designed to alter certain aspects of water quality, including pH, alkalinity, etc. However, it is difficult to find the correct dosage when using these products and you can never predict what other effects it might have on your tank

For this reason, you should avoid using too many chemicals in your tank. The only product you should need on a regular basis is a general-purpose water purifier or conditioner that can be used to remove chlorine and chloramine from tank water.         


Chlorine-free, filtered water is the best water for your aquarium because it’s clean and fresh. You may have an RO system already installed in your home that removes chlorine, chloramines, sodium, lead, fluoride, cysts, and a whole lot more.

 This kind of filtered water is wonderful for fish, so do not add them to RO aquarium water before giving them ample amount of time to acclimate.

During the move, your fish might be moving into a tank with a drastically different pH than the one being used now. To make sure they won’t go into shock, you’ll need to perform a pH test in the tank and the fish’s travel baggie beforehand.

Once you know the difference, you can add a ½ cup of water from the reverse osmosis tank to the bag.

Do this for the first 15 minutes of your new aquarium, until the levels match (approximately a .1 pH change each time) to help your fish acquire the new environment. If all goes well, your tank will be healthy and clean

Every aquarium is different and the parameters of the water in your aquarium will vary depending on the water source and the type of fish you have. The best thing to do is learn all about what you are putting in your aquarium to provide the healthiest environment for your fish.               

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