that "silent killer" article is terrible misinformation.
the beneficial bacteria which reside in the aquarium are too firmly attached to surfaces to be removed though the relatively mild suction of a gravel vac. while i will agree that using a gravel vac does of course rearrange the gravel so that the top layer is mixed throughout, this doesn't immediately cause the death of the bacterial population. while some may become trapped and die, most of them will slowly migrate back to the oxygen rich top layer. not enough of them will be so drastically lost as to cause dangerous ammonia and nitrite spikes - plus, you just cleaned your gravel really well and removed a large amount of debris which otherwise WOULD have contributed to rising ammonia and nitrite levels. in addition, most people do not clean the entire substrate every time they do a water change. they do 1/4 or 1/2, however much of it they can fit into the length of time it takes to remove the amount of water they planned on changing. not only that, but bacteria live all over the tank - on decorations, plants, glass, and of course - in the filters. MOSTLY in the filters because they have the most concentrated areas of food and oxygen, plus surfaces like biowheels and other media made specifically for bacterial colonization. if you clean the tank and your fish die, you have a bigger issue going on.
This is coming from Mr. I Never Actually Clean My Sand So I Don't Know What's Lurking In There. Sand can build up just as much crap and filth as gravel if it is not maintained. Has this guy ever taken a scoop of sand from his tanks and swirled it around in a bucket? That water is going to be Brown. With a capital B. I've changed a couple of my own tanks from sand to barebottom, and the removal of the sand was the nastiest thing ever - after perfect parameters and crystal clear water. At least with gravel, even though it traps a lot of debris, it is feasible to remove it. For every piece of poop that lands on top of your sand, another one melts into liquid and sinks in. In one of my tanks I am lucky enough to use a heavier-grade sand that allows me to actually use the Python on it without removing it. I clean the sand 50-75% with every water change - and you would be amazed at the little brown cloud that rises up every time the gravel vac gets stuck in there, at each and every spot.
The top layer of substrate is the lovely bacterial suburb of Podunk, Pennsylvania. Your filters are microbiology's answer to New York City.
These fantastic anaerobic bacteria can also produce hydrogen sulfite gas. This does not "bubble out" of the tank as innocuously as nitrogen gas, and if a large bubble is broken and releases into your tank, there's a good chance it could kill all of your fish. Toxic. Gas. This is why *most* resources recommend a sand bed no deeper than one inch, and regular stirring of the sand to prevent gas buildup. It can become dangerous when left alone. Even with my weekly water changes I still get small gas bubbles caught in the Python.
the beneficial bacteria which reside in the aquarium are too firmly attached to surfaces to be removed though the relatively mild suction of a gravel vac. while i will agree that using a gravel vac does of course rearrange the gravel so that the top layer is mixed throughout, this doesn't immediately cause the death of the bacterial population. while some may become trapped and die, most of them will slowly migrate back to the oxygen rich top layer. not enough of them will be so drastically lost as to cause dangerous ammonia and nitrite spikes - plus, you just cleaned your gravel really well and removed a large amount of debris which otherwise WOULD have contributed to rising ammonia and nitrite levels. in addition, most people do not clean the entire substrate every time they do a water change. they do 1/4 or 1/2, however much of it they can fit into the length of time it takes to remove the amount of water they planned on changing. not only that, but bacteria live all over the tank - on decorations, plants, glass, and of course - in the filters. MOSTLY in the filters because they have the most concentrated areas of food and oxygen, plus surfaces like biowheels and other media made specifically for bacterial colonization. if you clean the tank and your fish die, you have a bigger issue going on.
This is coming from Mr. I Never Actually Clean My Sand So I Don't Know What's Lurking In There. Sand can build up just as much crap and filth as gravel if it is not maintained. Has this guy ever taken a scoop of sand from his tanks and swirled it around in a bucket? That water is going to be Brown. With a capital B. I've changed a couple of my own tanks from sand to barebottom, and the removal of the sand was the nastiest thing ever - after perfect parameters and crystal clear water. At least with gravel, even though it traps a lot of debris, it is feasible to remove it. For every piece of poop that lands on top of your sand, another one melts into liquid and sinks in. In one of my tanks I am lucky enough to use a heavier-grade sand that allows me to actually use the Python on it without removing it. I clean the sand 50-75% with every water change - and you would be amazed at the little brown cloud that rises up every time the gravel vac gets stuck in there, at each and every spot.
The top layer of substrate is the lovely bacterial suburb of Podunk, Pennsylvania. Your filters are microbiology's answer to New York City.
These fantastic anaerobic bacteria can also produce hydrogen sulfite gas. This does not "bubble out" of the tank as innocuously as nitrogen gas, and if a large bubble is broken and releases into your tank, there's a good chance it could kill all of your fish. Toxic. Gas. This is why *most* resources recommend a sand bed no deeper than one inch, and regular stirring of the sand to prevent gas buildup. It can become dangerous when left alone. Even with my weekly water changes I still get small gas bubbles caught in the Python.
The snails are quite good at keeping the sand stirred up and free of large gas bubbles. However, a cory cat that uncovers a pocket of the hydrogen gas is going to drop like a rock.
