I wrote earlier about the different instructions I’ve heard regarding water changes in the fresh water aquarium. I’ll continue this by writing about usage of regular tap water when doing the water changes.

Using tap water in your freshwater aquarium is ok if you use water conditioner for example Tetra AquaSafe. I’ve used this from the beginning and every time for every 10 liters I put into the aquarium. This is common knowledge and I guess there shouldn’t be other opinions about this either.

But I’ve heard different variants on how to add tap water to the aquarium. When I do my water changes, I just turn the tap to cold (the coldest water I can get) and fill a 10 liters bucket with it while adding the water conditioner into it. In Finland the winters can be pretty cold so during winter time I add boiling water from a water boiler (not the hot water from the tap!) to the bucket in order to make it warmer. But I don’t usually do this during the summer. If changing like 20% of the water in the tank, adding cold water to it shouldn’t affect the temperature too much. And it will even out pretty soon anyway. I usually make sure I don’t pour the cold water in too fast and directly on some fish. This is how I have done it for all the past six year. Is this ok?

What Mr. Varjo says in his book is a bit different to this. He says the water should be room temperature and it should sit for some hours before pouring it in so that gases can evaporate from the tap water. I’ve never done this and also the local aquarium shop keeper has not told me to do it like this. Where could I store 30 to 40 liters of water for some hours before pouring it in, and how would I do that? So my question would be, how important is this procedure to let the water rest before pouring it in? And does it matter if the water is room temperature or tap water cold when you pour it in? I haven’t noticed any negative behavior from the fish after the water changes and they seem happy every time to get fresh water.

So I am again a bit confused.