How stable the rocks must be?

BlackTip

Active member
I am using dry Fiji rock. I am not doing fancy shapes; just basic mounds. I attempted to use JB Water Weld, but it didn't work. It hardens but, it doesn't stick the rocks together.

My mounds are somewhat stable, but I am not sure whether that is enough. I read people using cement, rods, etc. I wonder if it is necessarily, or just abundance of caution.

I prefer to glue the top few rocks together. Is there anything that I can use other than JB Weld?

Thanks,
 
it all depends on what you plan to stock your tank with. for example an eel or engineer goby will move the rocks around if not secure
 
In my opinion it is better to be safe than sorry. Anything that likes to dig in the sand or disturb the rockwork, will probably cause something to shift. It will either tumble and hit your glass or cause other problems.

If you are absolutely sure it can sit and be very stable you don't have to "glue" it down. But any rock sitting on the glass bottom needs to be directly on the bottom, not sitting on sand. I cut the base of all my rock flat and it sits directly on the bottom. nothing is moving it. Some is glued together, but a few pieces are just loose, but "locked in" very tightly with the rest.
 
it all depends on what you plan to stock your tank with. for example an eel or engineer goby will move the rocks around if not secure

No eels nor engineer goby. I am not sure what exactly I am going to stock, but I want it to be peaceful mixed reef tank. The rocks on the bottom are large and solid. It is the ones on top I am worried about.

Can power heads knocks those rock off? I am going to install 2 gyre 150; one on each side of the tank. It is 96" tank.
 
I just stack them securely, I don't glue just in case I get sick of the scape and want to change it
 
My two cents?

If you're worried about it, it's not stable enough. I am assuming you're still in the build stage and haven't started stocking yet. If that's the case, definitely use this time to get it right, because once you start stocking, it only gets harder to make any changes/adjustments.
 
I don't attach my rocks together. When I did the build I would see if the rock I just placed on the others is stable by seeing if it moves when I nudge it with my fingers while holding it; if it doesn't move then it's stable. The rocks shouldn't tumble unless they are placed precariously and a large fish then knocks one over. The advantage of not cementing them together is you can always rearrange them later if you want to.
 
In my tank (pic below) I have 5 large sections which were glued together out of smaller pieces with Dry-Lok and fiberglass rods. They intersect and fit together with the other large sections (but not glued) so tightly that there is no way for them to shift or fall. They all have the bottoms sawed flat and directly on the glass.

If I ever want to rearrange or take them out, it isn't just one huge chunk of rock in there. And there are a few small pieces that just lock into place and are very stable as well. The back wall is a false rock wall that is not connected to the main rockwork.

You may find you want to glue certain large pieces together for a stable base with which to add others. If you want ledges and overhangs, affixing them together is the only safe way to go. But there are lots of ways to go with it.

junetank.jpg
 
I used Dry-Lok...a fast setting hydraulic cement. You need to use it outside the tank, but it's a great way to put large chunks together. I show how I used it in my build thread. Let me know if you want a link to it.
 
my two cents?

If you're worried about it, it's not stable enough. I am assuming you're still in the build stage and haven't started stocking yet. If that's the case, definitely use this time to get it right, because once you start stocking, it only gets harder to make any changes/adjustments.

+1
 
I just balance mine, but it is tricksy: some rocks are tippy once the water gets in.
 
I stack mine securely as well

i like to be able to move them when i want. As mentioned before if your base rocks are on the glass and not on top of the sand this makes all the difference. I would epoxy the ones you are worried about. I used very little myself.
If you go for a more dynamic aquascape with bridges and towering structures definitely use the rods and such.
 
The rocks are on top of egg crate. I am going to put the sand afterward. I'd like to keep the rock without any adhesive, but I am worried about the few rocks on the top. They are smaller and lighter in size.

So, any recommendation about glue or adhesive? I feel cement is overkill. And JB Water Weld doesn't glue rocks together. I read somewhere someone recommended Gorilla Glue. Anything else?

Thanks,
 
I used Instant Ocean Hold Fast. It worked good as long as you are not trying to do something to off center( takes a bit to cure more than you are going to want to hold in place)
I didn't use very much of it, but what I did use ill have to break to get apart.
 
This might help with the WaterWeld. When you tried attaching them, did you put the putty in between the contact points and then smush the rocks together? I started off like that when I was making my scape (I used Vertex epoxy) and I was getting nowhere. Try putting the rocks together first, and then put the putty *around* the contact point and smush it into all the nooks and crevices. Also, if you don't go overboard with how much you use (and you shouldn't need to if you're not planning on having anything that could really give the rocks a beating), then you should be able to break the connections by prying them apart with a screwdriver (or something else that's safe to go in the tank) if you ever want to take it apart.

Hopefully something in there is helpful :)
 
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