live rock rubble as substrate, thoughts?

[Anonymous]

Things are moving on the new tank. Hardware will all be here in the next day or two and I hope to do the initial fill this weekend.

But in the meantime I've been thinking about rubble. As I've mentioned before this tank will not be using a sand bed; initially I was planning pure bare bottom and just letting polyps colonize the bottom glass to cover it. Now, I'm thinking about possibly doing a layer of live rock rubble as an alternative.

Rubble rock is cheap and easy to get, we're talking pieces the size of a golfball up to less then a softball or thereabouts. It would be a pretty simple matter to get ahold of enough to provide a covering layer over the bottom glass, really.

Pros are pretty straightforward... avoid the bare glass look, extra live rock for biological filtration. Anyone think of any cons? I'm thinking it'd have to be blown out regularly to keep it from becoming a detritus sink, but that shouldn't be any trouble.

Thoughts? Anyone ever try this?

 

[jusreefin]

Any shift in that rubble can cuase your entire rockwork to come crashing down and break the tank. Unless you have a MAJOR amount of flow all that rubble will just trap detritus, etc and just become a nutrient sink. Any type of cleaner you pt in may shift the rubble and cuse it to fall. IMO I would never run a tank this way unless there was no other LR being put in the tank. You can always put rubble in your sump for extra bacterial filtration.

You say blowing it out wouldn't be a problem but I disagree unless there is not other LR being stacked on top of it.

justr my .02c

 

[Anonymous]

No worries structurally. The actual rock would not rest on any rubble whatsoever. I'd use pieces of shelf rock for foundation pieces, themselves affixed to PVC pipe cutoff stand offs and the entire live rock structure assembled with underwater epoxy for better joins and plastic cable ties for added stability.

There will be a fairly major amount of flow in the tank (30x-40x turnover), and I'd be blowing out the tank to clean it on a weekly basis with a bare bottom tank as well so I'm not really thinking any added maintenance. Hell, the rubble could even be scooped out of the tank and bucket cleaned once a month for 15 minutes work

 

[bleedingthought]

Yeah, you'd have to do more than just blowing it out.

Maybe smaller pieces might work better though. But then again, all this sounds like what you would get if you used big shells for substrate... Trapping things under there all the same.

 

[fungia]

isnt going with rubble rock over the bottom similiar to using sand or crushed coral? i dont see a problem with it except for the detritus buildup.

 

[Anonymous]

Maybe smaller pieces might work better though. But then again, all this sounds like what you would get if you used big shells for substrate... Trapping things under there all the same.

Bigger pieces = much bigger gaps, much easier and effective blowing gunk out of those gaps. "Substrate" may be too strong a word, here, for the image it seems to be evoking. What I'm talking about is a thin layer, essentially 1 rock tall, not rubble piled on rubble.

 

[bleedingthought]

Pretty close to crushed coral, I would think, except that with golfball to softball size pieces will trap anything and everything that falls in there since there'll probably be such large gaps in between the rocks but will be difficult to scoop it out, especially if it's deeper.

 

[bleedingthought]

Maybe smaller pieces might work better though. But then again, all this sounds like what you would get if you used big shells for substrate... Trapping things under there all the same.

Bigger pieces = much bigger gaps, much easier and effective blowing gunk out of those gaps. "Substrate" may be too strong a word, here, for the image it seems to be evoking. What I'm talking about is a thin layer, essentially 1 rock tall, not rubble piled on rubble.

Oh ok, might be easier than I had pictured. With enough flow, you could get it to work, I guess. Try to do all the rock work directly on top of the bottom instead of on top of the rubble just so if you decide you want to pull it out, you still can.

But I think that your idea to cover the bottom with zoas would be pretty sweet!

 

[jusreefin]

Pretty close to crushed coral, I would think, except that with golfball to softball size pieces will trap anything and everything that falls in there since there'll probably be such large gaps in between the rocks but will be difficult to scoop it out, especially if it's deeper.

I would tend to agree with this. Also IMO it would just look like a cluttered mess in the bottom of the tank. I can guarantee after 2-3 times you would get tired of taking all that rubble out to clean it. You would be better off with a shallow sand or crushed coral bed and just vaccuming it once a week or so.

 

[Unarce]

Shouldn't be a problem, as long as you're able to keep it clean like you said. I came very close to doing this same with my latest tank, but I've got to have sand :?

 

[Anonymous]

Bleedingthought wrote:

But I think that your idea to cover the bottom with zoas would be pretty sweet!

Yeah, buttons, GSPs, fast colonizers that would take over a level surface given a little bit of time. It may still end up being the route I go. Thing is, it's possible I may only be in my current place for the next year or two and I'm trying to take that into account with my tank plans. The polyp-bed approach might be a real ***** to attempt to move.

Jusreefin wrote:

You would be better off with a shallow sand or crushed coral bed and just vaccuming it once a week or so.

::shudder::
No thank you. I was one of the earliest adopters of the deep sand bed approach way back in '97 and I've pretty much had enough of sand for awhile.

Unarce:

Shouldn't be a problem, as long as you're able to keep it clean like you said.

I think so... big powerhead, once a week, I really expect that to do the job. Make a worthwhile experiment if no one else has tried it; the rubble rock is cheap, I only need about 25 lbs worth, and if it doesn't work as well as I'd like it'd take all of 10 minutes to remove it from the tank.

 

[jusreefin]

There is a big difference between a DSB and a shallow one. I only run a DSB in my sump on my frag tank for nitrate export. My main display has a shallow 2" sand bed that gets vaccumed 2-3 times per month. I'm one of those people that love the look of a sand bed

 

[GSchiemer]

There is nothing wrong with your idea of a live rubble bottom. It's very natural and it will work well. You'll be able to move a lot of water without having to worrry about "blowing" around sand.

Be sure to include some Fungia corals on the rubble, which is their natural habitat.

Greg

 

[Rob Top]

I think it would be a haven for pods, they'd love it. Also would be great for pulling out frags of the zoa and gsp that will grow down there. I think it is a very good idea. I had a rubble zone in my 220 last time it was up and might again. Of course as you said, and others, keep it clean.

 

[Meloco14]

I think it is a great idea. Personally I would go with larger chunks of rubble. This will make them easy to take out if needed to clean, and easier access to sucking out the junk accumulated on the bottom. I don't see detritus build up being significantly more than if you went BB. You are going to have to siphon it out no matter what. As Greg mentioned, it is very natural. Most tropical fringe reefs are surrounded by a rubble bottom as opposed to a sand bottom. Fungia and certain clams will be right at home. Pieces of branch rock would make for an interesting bottom too. Post some pics if you decide to go this route.