How do I deal with this muck?


A reader struggles to keep his tank clean even after carrying out a water change. Expert Bob advises...

Q) When I carry out a water change on my tank, I syphon up as much detritus from the substrate as I can. But usually, within a few hours, there’s just as much there as before the water change, which is unsightly and looks unhealthy. I’ve sometimes even gone to the trouble of syphoning it off, letting the detritus settle in the bucket, and then putting the water back in the tank. Am I over-thinking this?


A) BOB SAYS: Detritus builds up over time in areas with minimal water movement. By syphoning it away with each water change you are helping to keep your tank physically clean as well as preventing the build-up of potential sources of ammonia, so I don’t believe you are over-thinking this at all.

Most aquarists like to keep their tanks clean for the benefit of their fish and also because aesthetically it looks better, although some biotope tanks require a layer of leaf litter to accurately replicate nature. The act of topping up your tank after the water change adds extra flow to areas that normal water circulation doesn’t reach, pushing out hidden pockets of detritus that your careful syphoning may have missed. By waiting for these to settle and syphoning again you are doing a thorough job, and one which is worthwhile, although I can sympathise with the frustration it can cause.

Depending on the fish you keep and how much water flow they are comfortable with, you could consider increasing flow around the tank with a large filter or some circulation pumps to deal with some of these ‘dead’ areas and keep detritus suspended longer, so filters have a better chance of removing it before it settles. However, if your fish are healthy and water chemistry is good and you are content to continue with your current meticulous maintenance schedule, then this is a welcome extra rather than a necessity.