If you follow me on Twitter, you probably notice that I do a lot of maintenance on my aquariums on Fridays. In fact, Friday is the day I do partial water changes, and I spend about two hours each week on this task. Why?
Second Nature
That is a good question, and the answer is simple. An aquarium is a captive environment, meaning that it is only a cross-section of nature, and not nature itself. In a river, fresh water is being added constantly, and old water washed to the sea. In a lake, runoff and rain do similar.
In a captive environment, the aquarist must take that job. Even in a healthy tank with mature mechanical and biological filters, there are trace chemicals that build up over time. There can be harmful bacteria that builds up over time. Performing a 25% to 35% partial water change helps to keep a tank healthy.
Without water changes, eventually unhealthy substances will accumulate and the fish will be more susceptible to illness.
Out With the Old
While some avid aquarists with dedicated fishrooms construct automatic water change equipment, most of us don’t have that luxury. For the rest of us, it’s buckets and syphons. Here is a video I made about a year ago that demonstrates how to use a syphon.
Some small tanks like the one in the video or smaller are easier just to use a large cup or small 1/3 gallon bucket to scoop out water. The smaller the tank, the easier the water change. To a point.
In With the New
Getting the water into the tank is the next step. Steps must be taken to neutralize chlorine and chloramines in tap water. These kill bacteria, but they also kill fish. The temperature of the water must also be about the same as the tank water. (In this discussion I’m assuming tap water is going into the tank and not RO or DI water.)
I have my larger tanks set up to allow dumping of a 5-gallon bucket directly into the tank. I accomplish this by strategic placement of a large rock at the “landing zone.” In other words, I gently dump the bucket onto the rock, and that prevents the substrate from being kicked up. In smaller tanks, I use a smaller container, and I use my free hand to disperse the energy of the incoming water.
Fish Love It
It might surprise you to learn that, at least in my experience, fish are attracted to the incoming water. I think that is true for a couple of reasons. First, the new water has a lot of dissolved oxygen, and that’s how fish breathe. It’s like when we step outside to get a breath of fresh air.
Fish that like a lot of current are attracted to any fast-moving water in the first place.
Fish are curious creatures. Any time something is added to the tank, the fish do notice. Not all species care, but many do. New water coming into the tank is a novelty to them, and they come by to check it out.
An Alternative
There is another method for people who don’t want, or can’t do all the bucket work. It’s called a python, and it will do much of the work for you, provided you have a sink close enough to the tank. I have not tried this, but other aquarists swear by it.
How Often?
Regardless of how the water change is performed, it’s generally recommended to perform 25% to 30% changes every two weeks. (I do water changes every week because I have multiple tanks and I alternate.)