Any cons to...

Is there any downside to raising the rock off the bottom glass with something like pvc or eggcrating vs. just setting the rock on the glass then filling in with sand around it?

I'm thinking it will allow for better flow under the rocks and won't prevent any of the cleanup crew from getting into all areas to do their job. Under the rock would be mainly bare bottom other than whatever is used to raise it up, then the sand will just be filled in around it.

Thanks

 

Many have done that. PVC sections keep the rock off the sand and help keep it from compacting.

Go for it!

 

For reef tanks containing animals that sift and stir the sand, this is the preferred method. I had a tomato clown that was notorious for its incessant excavation to the point where rocks tumbled as a result.

Your proposed method is a solution to this problem. Great idea!!

Furthermore, raising the LR off the sand somewhat will expose more sand to water--another plus.

You accomplish a number of positive outcomes by raising the rock off the sand. You discourage rock tumbling, you maximize the water to sand contact area; and creatures in your tank like gobies, starfish, jawfish, brittleworms, etc. can sift to their heart's content without danger of destroying the aquascape you've created.

Put simply, I think there's no downside to your proposal.

Let us know how it works.

 

sounds great.might be alot of work.my bottom row of rock is a series of caves so more water could contact the sand.

 

Sounds like a good idea....

 

Well for what ever its worth when this idea was first floated around I tried it saw no real benefits to it. But pondering the idea over the yrs and also haven tried it I found that with these dead anaerobic zones this created it was a natural nitrate reducer to a point. Its a totally dead area and nothing can get at it and its a mini denitrater .. And unless you just reach in and lift the rocks it can do no harm far safer then a DSB and does about as good a job with the NO3 reduction . I know the systems I did suspend the rock in had more of a NO3 problem then the ones I did with the rocks on bare glass and sand about 2 inches around them all ..

 

Elevating the rock off the substrate helps to reduce diffusion and advection!!!! If you are able to secure the rock properly to avoid falling rock and injury or death to fish, corals and sessile inverts etc. then great!
If you wish to go the other route and place the rock in the sand, then it would make sense to securely cover some of the rock in the sand/substrate so that it is compatible to pouring concrete around poles for a deck or porch!!! Stability and strength!!!!!
Plastic wire ties and epoxy is also a good ideal to adhere the upper level of rock work from tumbling down!!!
Eventually, if you add corals, their growth and spreading from rock to rock will further enhance the bond between rocks preventing problems later on.

 

Thanks for the replies everyone!

Coral Reefer : Can you talk a little more about the benefit of reducing diffusion, or at least tell me if I follow what you mean? If I understand diffusion correctly, it's particles or substances moving from a high concentration to a low concentration.

This is just a guess but is the benefit then that waste and other undesirable particles will stay more concentrated and then moved out of the dislpay (advection) and are then easier to filter out of the water?

 

i hope this is right.when the waste goes to an area where it is starved of light and much of the oxegen,such as the pours in lr and when it seeps into sand or a plenum or a cave,it starves off nitrates and phosphates.i hope i'm close.idk exactly how it works i just know it does.i'm sure someone will be able to explane better.

 

Animation: How Diffusion Works
Advection is the transport of chemicals, molecules etc. through the flow of gas or liquid.
To see how these processes actually work just look under a piece of live rock that has been in the tank for a while and you will witness an accumulation of detritus and other substances that settle there through the process of advection and diffusion.