Surface area

[jinks]

I was reading through a post to a newer member and they were asking how much rock and sand they need. The response was the more the better. While that is not bad advice as its not going to hurt any thing to have extra is it really necessary? Good porous rock has a very large surface area in relation to its size. Sand has an even greater surface area then that. Only enough bacteria to consume the waste produced can live in the tank. Any one have any experience as to the tipping point? I know that it would be to hard to get any real math going because of the amount of variable, Just looking more so for opinions. I guess an ammonia spike would be the first indicator that you let things tip the wrong way. Almost seems like a 1 inch layer of sand should be enough to take care of a moderately stocked tank. Might make things seem a little less expensive to a lot of new people trying to figure how to swing this hobby.

[mr.maroonsalty]

Im not sure I agree that one can't have too much lr in a system; I think it far more important to design a system and rock scape that traps as little detritus as possible. I think of sumps filled chalk a block with lr sitting down there trapping crud, or the once common rock wall stack that traps everything that finds its way behind.

[dkeller_nc]

As far as denitrifying bacteria, I would imagine you're dead-on. The surface area in a reasonable sand bed should in theory support more than enough bacteria to consume the ammonia produced by a tank's critters.

And while this example is at the hands of a bonafide expert, check out Julian Sprung's "wave tank" on YouTube. There is very little live rock in that tank, and it's heavily stocked. It also has no skimmer.

That might not be ideal advice to give to a beginner, but it definitely shows that it can be done.