Things to consider with a bare bottom tank
Bare bottom tanks definitely have their pros, cons and special considerations. A few things that I've learned over my year of going bare bottom is you don't really need star board, you need to have special consideration for marine life, you need to plan for detritus removal, you might be suprised where your coraline grows, you may notice live rock shedding and your aquascaping may get a little rocky.
It seems that a lot of people think you need star board to go bare bottom. If you ask yourself why do I need star board? The only logical explanation is to protect the bottom glass. I've seen plenty of tanks with glass bare bottoms with the rock right on the glass. If I were to go at it again I'd lay a thin agrocrette bottom right on the glass.
Once you've gone bare it should be obvious that sand dwellers are not going to be happy and other fish may be bothered as well, such as wrasses. I do know that the lined wrasse do not need sand beds so not all wrasse are off limits. Do your homework before you buy your fish. Another thing I've noticed is that hermit crabs seem to have a hard time gripping a bare bottom. I've seen them get blown helplessly on the bottom. You may want think twice about your invert selection as well. A lot of stars are detrivors, no detritus equals no food. On the coral side of things you may want to think twice before mounting an encrusting chalice or other encrusting coral on the bare bottom. The reasons being is there is no way to frag your tank bottom and prune your coral back helping to avoid coral warfar.
A benefit to going bare bottom is detritus removal. If you set your scape up with a little forethought you can create detritus traps in corners where you can easily siphon it out. I chose to go with star board and leave a 1" gap in between the front glass and side panels as Detritus trap. I am very happy with the functionality of this system. With enough flow you can suspend most of your detritus and catch it in filter socks. It seems that the water flows faster in a bare bottom setup as well.
Coraline algae is something we all want our tanks to be covered in. However, the white bare bottom star board seems too bright for deep dark purple coraline to grow. Instead, I notice the coraline growing on the starboard under shelves and in caves the most. I would bet that if you used black for your bottom the coraline would grow much better.
If your converting your sand bottom tank to a barebottom tank be prepared for the shed. The weeks following the transformation you will get a suprisingly large amount of sand that you'll want to siphon off the bottom. After the initial shed you'll still want to siphon occasionally as the rock seems to always shed a little.
Lastly, aquascaping on a bare bottom setup will immediately pose some issues. If you're using starboard your probably going to find out that it floats. To get around this I siliconed mine down. You can use the weight of your scape too. When scaping in sand you can sink irregular shapes in the sand to hold them steady. With a bare bottom tank you can get a rocky scape if you don't plan your foundation. I personally used a grinder to create flat bottoms on my base rocks. It's probably best to use bigger pieces and avoid complex stacking structures unless you engineer your scape with much consideration.
Setting up a bare bottom tank can have its challenges, but with some consideration can be set up in a fashion that provides a better way to export detritus and help keep a low nutrient system. Cheers and happy reefing
