Crushed Coral vs Sand

H

hultman

Curmudgeon at large
Sep 19, 2004
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Minnesota
After being out of the hobby for about five years, I'm setting up a Fish Only 40 gallon hex, with a small wet/dry, 8W UV and a very old skimmer of unknown brand.

My question is about substrate. I have a huge supply of old crushed coral from my previous salt tanks, but I read on this forum that sand is somehow better. I don't plan on using live rock or live sand, and I am not seeding from an existing system. I've soaked every part of the old system in chorline, after which I let it soak in the lake for a few days.

The comments that interested me are references to benficial anaerobic bacteria hosted by the sand that wouldn't be with the crushed coral. 15 years ago, we thought that this would be a bad thing. Have things changed? Does this anaerobic bacteria significantly benefit an FO tank?

Thanks! Appreciate any comments on this.

Jim
 
Yes, it does. The anaerobic bacteria break down the nitrates, which otherwise would have to be removed through water changes or algae cultivation. In a FO, this helps out significantly, though may not be as important as it is in a reef setup. One problem is keeping the maintenance critters alive--the fish selection may prevent these critters from thriving.

I would also reconsider not using live rock. It's an important aspect of filtration, as well as providing suitable hiding places for the fish.

Are you planning on running the UV full time on the main tank? If so, why? Adequate quarantine is much more efficient for controlling parasites, and the UV sterilizer will be just another piece of equipment to spend money/time maintaining.
 
Yeah, nitrates were always a problem, and I did regular water changes on the old system. Perhaps I'll give the sand a try.

Hiding places should not be a problem. I have a ton of interesting old structure, mostly rock and coral formations. What kind of filtration does live rock do? I realize that any surface will host bacteria, but what else?

As for the UV, it will be on 24/7 and I'll change the bulb every six months. I had some bad experiences with ick and other problems in my previous system, but once I installed the UV, they went away. Maybe it was coincidence, but it really made me a believer! I did run a quarantine/hospital tank on the old system, but don't intend to this time. I suppose I could set up a temp for new arrivals, but this is a small system and I suppose I'll have four or five fish.

Thanks. I've been out of this for a long time and I appreciate the input.

Jim
 
Actually, if the rock you are using is porous, it acts the same way as the live rock, eventually. Purchasing the rock provides some bacteria colonies, and also introduces a diverse population of micro-fauna, a good thing IMO.
 
Live Rock

If you dont want to put LR in the tank,you could go to your LFS and get live rock rubble fairly cheap and put in your sump.It will still filter the water as well as add a place for pods and such to grow.....just an idea.
 
You want pods and micro fauna because they are a great source of natural food/clean up crew in your tank. Also if you'll add just a little live rock to the coral and coraline rocks you have it will turn to live rock. If you have enough of it you don't have to do nearly as much work . Your water quality will be much better and you won't have nearly as many problems with ich etc.
 
On a natural reef system, everything is food for something else, even the byproducts you dont want like nitrates, ammonia, and nitrites. The whole ocean is coverd with a sand bed, there had to be some benefit to using in a SW system because its like that nature. It was eventually found out it lowerd the nitrates due to bacteria living in low oxygen enviornments, they take the oxygen from the nitrate, making it into nitrogen gas that bubbles out into the atmosphere, and sand doesnt trap detritus like CC does, which makes it easier for the clean up crew to get at it.

Pods as stated are tiny sometimes microscopic arthropods which show a healthy system. Besides being food for fish fry and other types of fish like Mandarins, they also clean up any detritus left behind which prevents it from decaying into nitrates, which is done on a natural reef system.
 
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