LR placement when building a reef - what should one be concerned with?

[rsteagall]

When I put my tank together (close to a year ago now) I piled the rock up and didn't pay much attention to how much of a footprint of rock was actually sitting on the bottom of the tank. I seem to remember reading several times about limiting how much rock actually touches the bottom of the tank.

What is its importance in limiting this and what ill effects should one expect if too much is actually resting on the bottom? Why does it really matter?

In putting this nano together, I would like to take this into consideration.

-Ryan

 

[c_stowers]

The more that touches the bottom, the more detritus that can collect under these rocks. However, sometimes it's hard to get the needed stability for a tall reef without having alot of rock touch the bottom.

 

[TitansFan]

Just an idea... I plan on putting my rock on "pvc rings". I am going to take a wide pvc pipe, a hole saw and drill holes in the pvc. Then I shall cut out sections. This will give me a u-shape on top to cradle the rock and an upside down u on bottom to at as feet. I hope that explains it.. When i actually get to this point I can take pics. I am doing this to lift the rock out of the sand. I also have thought about a sand shifting goby. I do not want to take the chance of him digging under rock and causing it to collapse on top of him.

 

[gflat65]

I placed most of mine all the way to the glass when I added most of my rock to the 125. With an engineer goby, if you don't, you will have daily landslides. I usually use small pieces of rocks as bases so I can stack above my sand bed, though.

 

[DMBillies]

I have heard the PVC idea and it sounds like a good one, though to me it also sounds a bit unstable (at least the way I build things). Like you, the first time I set-up a tank I just piled stuff in. However, I recently moved and when I put everything back up I got some rather large pieces of base rock (not very holey and heavy, so it won't create the detritus problems that live rock will and won't shift on you) and put it in a layer under my lr. If you use this method, be sure that the base rock is resting on the bottom of the tank (not on the sand) and that the sand goes in around these. I have a sand sifting goby that toppled stuff all of the time before I tried this and have had 0 problems since I moved.

A method I have heard of but don't have any experience with is in actually drilling holes in the lr and then putting plastic dowels in them to hold them up (like houses built on pilings at the beach). The dowels can also be used to hold the pieces of lr to other pieces of lr so that higher pieces don't topple into the glass or anything. It sounds like a pain in the butt to get set-up initially and to plan out where all the rocks can go (which is why I didn't do it), but it probably works wonderfully once it is up. Again though, I have no experience there.

 

[gflat65]

You can also build PVC structure that mimic rock in the wild and strap the rock to the PVC strucure with zip ties. Coralline will cover the ties in no time and the rock covers the PVC. I may do some of this with the 180...

 

[TitansFan]

I had planned on using very wide diameter pvc. This would give me a wide base to stack on. I had also thought about the zip ties. They sound like a good idea if you can get over the initial look of it. If I could only convince the wife to go BB....... but, I must keep the accountant aka wife happy or the monthly tank allowance goes bye bye.

 

[DMBillies]

I wasn't knocking the PVC idea (either Gflat's or TitanFan's) I was just saying that my constructions skills are non-existant...

Also, I had a thought about the zip ties (my father is an electrician and zip ties are our duct tape... you can do anything with them). I know from experience that the white ones are very sensitive to long-term exposure to light. They get brittle and break. I'd do your homework on this as I've never used either type in a tank, but I know that black ones hold up up better to light. They will also probably be easier to hide until the tank has a chance to cover 'em up. Just another thing to think about

 

[fishdoc11]

Building a structure that is open and not like a brick wall is the most important part IMO. Giving yourself plenty of room to reach around behind and on the sides of the rocks is also a good idea but is hard in shallower(front to back) tanks. Basically you want to eliminate places where detritus can build up and not be removed by some means and where good flow will be able to reach all portions of the structure. If you are using a sandbed putting the live rock structure on the bottom of the tank(or spacers of some sort like the PVC mentioned above) before filling with sand is a good idea to prevent rockslides from burrowing creatures etc..... Also with live rock less is more IMO. Not filling the tank all the way up and leaving room for corals to grow out and fish to swim is a good idea(something I regret that I didn't do in my 90).
hth, Chris