I am just about to start fishless cycling my 55g tank which is currently all gravel but I keep coming back to look at some corys....
I am planting a fair amount and like the look of the gravel so really want to keep it but would also like to put in some sand to make the corys happy
I have read lots of things about the issues keeping the sand and gravel separate and came up with the idea of effectively putting some sand inside a bowl. I haven't quite worked out the details yet but was thinking that rather than try and have two substrates sat on the bottom of the tank I could effectively put the sand in some kind of bowl. I was thinking something like a large petri-dish (or perhaps cut up a Tupperware container) to which I could glue pebbles around and effectively give me a removable sand patch.
My concern is that in doing so I am stopping flow under the sand. If I had 15mm of sand would / could this cause any problems? Would say a 120mm circular path of sand actually be worth it?