Need Advice: How to cover the bottom of your tank

[FitoPharmer]

My tank is BB, but it also has a tile bottom. You can get reef safe tiles that would help block light and promote coraline algae growth. I have seen them up to 1'x6". Then you could tape the seems from below or wait for the coraline to take hold to block the rest. My first tank was BB and the fuge light bugged the main tank for a long time until the coraline covered the entire bottom. My 6' 120G cost ~100$ to do with 4"x4" tile.

[intarsiabox]

There's another type of duct tape that looks like polished stainless steel. It is completely opaque and would also help reflect some of the light back down into your refugium. I'm not sure of the name of it but I've used it in some homemade light reflectors or to improve some cheap store bought ones and it is not effected by the heat and does not come off. It's more expensive than duct tape but still would cost under $10 for the amount you need.

[lastlight]

Great idea. I was going to suggest tinfoil but the tape will be easier to apply. Both will block all light.