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How Often Should You Replace Fish Tank Light Tubes

Every fish shop and vendor of aquarium lighting tubes seems to suggest replacing your light tubes every 6 months. This is down to the useful UV light that a tube emits depleting over a period of time and manufacturers tend to put a time scale of 6 months on this. So we want to know how much truth is there in this and how often do you replace the lighting tubes in your fish tank?


This does depends on the quality of the tube as to how long they will last. A quality T-5 tube will easily last a year for most aquarium owners as they are rated for 10,000 hours. When you notice that the ends of the tubes start to turn grey or black it is my rule of thumb as to when they should be replaced. Another tell-tale in a well planted tank is if your plants are not doing as well as they once were with all other conditions remaining the same. This can vary from 6 months to well over 1 year. Tubes that are made in China will not last as long as tubes made in Germany. Buying cheap tubes is often false economy as they do not last.

If one had a light meter that measures lumens they could compare the light output of a new tube verses a 6 month or 1 year old tube and this would give an exact time of when they should be replaced.

If you are considering replacing your aquarium light tubes then why not think about changing to LED lighting – we have done a summary of the costs involved in an article about whether upgrading your aquarium to LED lighting is worth it.

As a rule of thumb though, it is not essential to replace every 6 months however keep an eye on them and how you tank looks and if you want to treat your fish to some new lighting then don’t hold back, they are your pets to be spoilt after all!