Spiral what are you thinking of using instead?
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rock rubble.
I have egg crate racks in a 40 breeder where I grow out some corals for trading. I figure having a layer of rock rubble covering the bottom where I can just place the frags would be way better. They can grow out onto other rocks. I can take out pieces to clean off any problem algae.
I have one of the eshopps acrylic racks with magnets too. For a small rack it works well and you can take it out and give it a vinegar soak when it gets dirty. The acrylic attracts algae too, but the smooth surface is a lot easier to clean than all the sides of the egg crate.
I'm not sure what a good way to raise your sump would be. a layer of silicon map would make it quieter, but I doubt has the height you are looking for.