I bared my bottom about nine months ago. Took some doing, since I'd always had coral sand in my various tanks for over 30 years. Yes, I like the aesthetic appeal of a white sand bottom. However, I got fed up with diatom patches on the sandbed that eventually failed to respond to anything I did, short of potions, which I'm not going to use, except in a quarantine tank.
I could've replaced the sand, but wondered if I was simply making a rod for my own back. I have a large stock of soft corals that appreciate the fish being heavily fed. In addition, I was feeding very well to make sure my Copperband butterfly and my Regal Angel were getting enough food in a very greedy environment.
The key thing that swayed me was that I realised that I could point my two Jebao WP40 powerheads down at the bottom glass to sweep crud away and create strong upflows. [My tank is 5'x2'x2' and needs all the strong current it can get.]
Then, when I gradually cleared all the coral sand away, I noticed something that gave me further food for thought, and suggested to me that I'd made the right move. It was the sheer amount of crud that I could now see accumulating - even over just one week! Before, for years and years, having a coral sand bottom had disguised just how much crud was piling up. Admittedly, as I said above, I was feeding heavily [at least 5 cubes of frozen fish food per day, plus flake or mussels, or marine grazer rings, etc], and also my Yellow Tang does - as they all do - poo for Britain, a piscatorial dung machine. Nonetheless, it was an eye-opener, even after all these years of marine tanks.
Yes, I do miss the beauty of a pristine white sand bed, but I wouldn't go back, not with my current tank.
Here's what my experience suggests to me:
Against baring your bottom:
- Rules out some wonderful wrasses. [The silver-bellied yellow wrasse is one of my favourites; not that great-looking in lfs tanks, but once settled in, it positively gleams, is always about, troubles nothing else and - only sometimes! - will occasionally eat flatworms.]
- Aesthetically, takes some getting used to.
- Crud can become visible in a way it wasn't before.
For baring your bottom:
- Can increase the tank's water flow without creating a sandstorm. Most fish appreciate this, and many [though not all] corals.
- This increased water flow can improve the efficiency of your live rock, especially if your rock is nicely opened out by the use of acrylic rods or cable ties, etc., rather than just lumped down together.
- The crud can be seen and siphoned out during a water change, in a way not easily possible before.
- Diatoms and cyano find it less easy to take hold on a bare bottom, especially with the increased water flow.
- The tank bottom gradually becomes encrusted with green and purple, becoming a bit less aesthetically challenging.
Discussion points for further rumination:
- With a bare-bottom tank, does the ability to siphon out the crud more easily then make old-tank syndrome [in which a mature tank seems not to thrive any more] less likely?
- Does the absence of coral sand on the tank's bottom affect - perhaps in the long-term - the tank's carbonate hardness and/or PH levels? [In the early days of marine tanks, it was commonly held that coral sand helped stabilise the tank's carbonate and PH levels. However, if the sand is mature, does each grain become so coated with organic matter - bacteria etc - that the sand doesn't function in that way?]
NB: My tank experience discussed above is for a fish + soft corals + RTB anemone reef. I have no lps or sps corals in the tank.
