No, absolutely not!
Water changes are by far the most neglected chore in the aquarium hobby. Over the years I have seen countless nitrate test kits turn dark red, indicating a nitrate level above 120 ppm. Obviously, these were other people’s tanks, rather than my own. High nitrate is the number one indicator that you haven’t been changing your water enough.
When most people enter the hobby they come with a minimalistic mindset. How much work can I avoid doing? However, if your fish are to live for any length of time, this mindset has to change.
Over the years I have experimented with many different water changing routines, ranging from nothing to greater than 50% a week. Yes, you did read the word ‘nothing’. There was a 133 litre aquarium that went without a water change for over a year. This has given me great insight into the value of water changes and the consequences of neglecting to do them.
Hard and Fast Rule
Over the years I have recommended various water changing schedules to different people. While there were reasons for all of them, I have come to the conclusion that a 50% water change once a week is the best way to go. This may seem like a lot to most people, however, the benefits of maintaining a tank in this way far outweigh the cost in time and labour.
Why should I do 50% water changes?
There are several reasons why you should change 50% of your aquarium water at least once a week:
Nitrate levels – 50% water changes keep nitrate at a minimum. While nitrate is non-toxic to fish, you will be surprised at the difference that a low nitrate level makes. It is a common misconception that most fish will not readily breed in the aquarium. However, it is often the water quality that prevents fish from breeding. Fifty-percent water changes ensure that water quality is optimised as much as possible. Under these conditions, most fish and even invertebrates will breed readily. Even if breeding is not your goal, breeding is a sign that the fish are healthy and happy. Most of the eggs or fry will be eaten, so your aquarium will not become overcrowded overnight. Plus, breeding is always fun to observe.
Nutrient levels – If you add fertilisers or any sort of pH/KH/GH buffer to your aquarium, then 50% water changes are a smart idea. While working in an aquarium store I witnessed so many water tests come back perfect except for exceptionally high GH levels. There could be zero ammonia, zero nitrite and zero nitrate but the GH levels were off the charts, literally. This alone can be enough to kill fish, especially those originated from soft water environments.
Also, if you have a planted tank then nutrients will gradually accumulate through the daily or weekly addition of fertilisers. This can cause algae problems if not addressed. Fifty-percent water changes essentially ‘re-set’ the aquarium after a week of dosing fertilisers by bringing the nutrient levels back down to negligible levels. This way you always know what the nutrient levels in your aquarium are.