Have all gravel substrate at the moment. Would like some sand for corys so am thinking of doing half sand andhalf gravel. I would like a divider inbetween and slightly above the 2 substrates to minimise them both mixing together and also for easier cleaning of the 2 substrates. If I was to use aquatic safe silicone to stick a few pvc pipes together (pictured below) so they would protrude an inch or two above the substrate and then use the same silicone to attach gravel/stones to the piping (pictured below) Do you think this would look ok and act as a good barrier to stop the 2 from mixing. I know over time little bits will mix eventually but this should minimise it alot and be alot more manageable.