Rock under Live rock

[cherijon]

I've seen in several places the idea of jacking up LR on a couple inches of PVC tubing and was wondering if anyone had instead placed their rock on to of thin flat rock buried in the sand. I'm thinking of burying some 2" thick pieces of flat granite and marble which I have and then placing the LR on top of that instead of burying the LR into the sand. I have a 3" sand bed so the LR would still be partially into the sand. Any thoughts? Thanks

 

[Biggen]

I think what you are wanting to do should work fine. Make sure the base rock is pushed down a good ways in the SB.

I did the PVC pipe thing under my LR. If I had to do it again, I probably wouldn't though. It's a lot easier to simply push the LR into the sand a few inches than to glue 4" PVC to the bottom of the tank.

Incase you don't already know, the advice of putting PVC (or anything for that matter) under the rocks for support is so that as the SB dissolves over time, a rock slide won't ensue.

 

[cherijon]

I did not realize that that was why. Dissolving sand hadn't occured to me.

 

[Wally]

Hey all, if I were to do it again I would get what they call at my lfs lace rock. It appears to have once been on the bottom of the ocean (looks like dead live rock) and costs only $1.99 per pound.

Next time..............

 

[cmor1701d]

as the SB dissolves over time

Biggen, where did you come with that? I have never read anything that says the sb will dissolve over time.

Critters may move sand a/o rock around and cause it to move. Raising LR above the sb also prevents dead areas where hydrogen sulfide could form and accumulate. The idea is to have the platform or the rock directly on the bottom glass. Most people seem to just push the rock down far enough into the sb so that it is stable.

 

[Biggen]

Biggen, where did you come with that? I have never read anything that says the sb will dissolve over time

I should have been more specific. Aragonite sand will dissolve over time. Although I wouldn't see why CC wouldn't either. That is one of the reason Aragonite sand is used so heavily. When it dissolves, it releases buffering agents, CA, trace minerals, etc. However, in a normal aquarium, the SB dissolved has no major impact on these minerals.

I am really not sure on the chemistry of how it dissolves. Essential Co2 trapped under the sandbed can lower the pH causing the SB to dissolve over time. This is basically how a Calcium reactor would work if loaded with Aragonite. Be aware, that Aragonite will also dissolve up to a pH in the high 8.0's. It is inevitable that part of the SB would need to be "topped off" with new sand.

Someone may be able to explain that a little better that I could. You could also do a search on "aragonite & dissolve & aquarium" in Google and should come up with something.