What is the best water to use in a fish tank?

Here are we going to look at different water sources you can use for your fish tank or aquarium. If you care about your fish health and well being then you must understand these water sources. It’s pros and cons. Danger it poses and how to optimize it. Use of right kind of water for fish survival cannot be overstated.

Tap water

Depending on quality of water in your location, tap water is perfectly fine for freshwater aquarium. If unsure you can check with your local fish store about the suitability of tap water for aquarium.

Note that chlorine and chloramine are usually added to tap water to kill bacteria for safe human consumption but for your pet fish chlorine and chloramine are harmful. They also kills ‘good bacteria’. So if you decide to fill your tank with tap water then you must dechlorinate it.

There are many inexpensive water conditioner products available in the market for this purpose. Not only do they remove chlorine and chloramine, they also remove heavy metals found in tap water. 

To use water conditioner simply add required amount to the water stated in the label and leave it undisturbed while it removes chlorine, minerals and heavy metals.

Doing so will also introduces good bacteria in your tank ecosystem. These bacteria will break down ammonia, one of the main cause of fish death and nitrate from fish waste. Without these bacteria your fish will not survive.

Well water

Well water is another readily available and cost effective option. Unlike tap water, well water do not have chlorine or any other chemical added to it. So is well water safer choice than tap water? Not really.  It is unregulated source of water so the quality is undetermined. It has high chances of being contaminated with fertilizer and pesticides. And usually well water have less oxygen in it.

Just as tap water you also need to condition well water and make sure pH level is suitable for fish before adding it to tank.

Purified water

Purified water is also called distilled water. As name suggest purified water is pure water without any chemicals, minerals and nutrients. If you simply use pure water without treating it, your fish will die due to lack of calcium, magnesium and sodium You will have to add nutrients and control pH level to make it habitable for fish.

If you opt for purified water then prepare to add right amounts of nutrients and maintain pH level every time you change water. This can be quite cumbersome. Any sudden change in water quality will shock fish and even kill them.

Distilled water may not be practical for large tanks because of the sheer volume of water you need to to fill up the tank. Easier alternative is to use tap water with water conditioner applied to it.

Bottled water

Bottled water does not contain chlorine and heavy metals like tap water and at the same time it is not stripped of minerals and nutrients like purified water. So bottled water may seem like a sure winner but you have to consider the cost. It is an expensive option compared to tap water and well water specially if you have a large aquarium. Your cost of maintaining fish tank will increase significantly.

If you decide to use bottled water then always check the bottle label before using it. Different brand have different amount of mineral and nutrients. pH level is also not standard. In some cases it can have high level of chlorine so you have to treat with conditioner before using it.

Rain water

Rain water can be another natural water source for your fish tank but there are couple of things you need to consider before you settle on using it.

This option is feasible only in area that gets frequent rain.

Generally rain water are low in mineral. Softness and low acidity of rain waiter can be suitable for some type fish but other it may not be ideal. To thrive these types of fish need higher acidity found in water source such as tap water. So if you use rain water, make it a gradual process. At first make your water composition – 25% of rain water and 75% of currently water source you are using. If you don’t see changes in fish behavior then next time when you change water you can increase the rain water portion.

Other factor you need to consider is the air quality of your area. Bad air quality equates to polluted water supply unsuitable for fish tank. 

It is best practice to collect rain water in clean container and make sure it does not get contaminated during water collection. Water collected from roof may contain asbestos from shingles.

Lake/River water

Lake or river water may seem like an obvious choice because after all it is a natural habitat of fish but is it really ok for fish tank?

River/Lake water contains parasites and diseases which pose significant threat to your fish health. There is also high possibility of water getting polluted and contaminated by different sources such as industrial and agricultural chemicals, animal excretion and human waste.

This makes river/lake water unsuitable for usage. Also, it maybe quite impractical to fetch water from river/lake every time you change your tank water.

Reverse osmosis

With reverse osmosis (RO) system you get pure water. It can filter over 90% of contaminants from water. But downside to RO system is that it also filters out minerals that you need in water for stable pH. Without it , it can wreck havoc in pH level. You have to remineralize water to make it safe for fish.