Best cement for larger rocks?

[Gregg @ ADP]

Hey, everybody.

I’m going to completely redo the scaping on a ~400gal that is 36” high. The current aquascape is somewhat bulky, and I really want to open it up with a few structures that are more vertical w/shelving.

A lot of the rock pieces are 10lbs and up...some 25lb+. My thinking is that I might drill through and use rods....but having done that before, it can be kind of a pain, but more importantly, it doesn’t leave much room to change things as you’re building.

Because of the weight of some of the pieces, I’m not going to waste time with any kind of 2-part epoxy or glues.

What would you guys recommend? Is there a good reason to not use Quikrete? Thanks.

 

[Flippers4pups]

I've used quikrete hydraulic cement and fiberglass rod with great success. Rod's help keep the structure in place till the cement hardens.

It will set up quickly, so small batches are best. Working time around 5 mins. Let cure overnight.

 

[Be102]

Also looking for a good cement on rocks, following!

 

[jsker]

I like a product called Stone Fix. Stone Fix is a product designed for reef tanks that is a hydraulic cement. I have used it in the past and it work very well I even used it wet in the system to secure a rock that kept breaking lose.

 

[Gregg @ ADP]

I've used quikrete hydraulic cement and fiberglass rod with great success. Rod's help keep the structure in place till the cement hardens.

It will set up quickly, so small batches are best. Working time around 5 mins. Let cure overnight.

Have you ever had any issues with the quikrete coming apart after awhile?

I’ve used rods a bit in the past, but for this project, they might end up being more trouble than they’re worth if the primary benefit is simply to hold the structure in place. I’ll probably end up propping the more adventurous parts up externally with PVC.

 

[Be102]

Does anyone know of cements that are in local stores such as Home Depot and whatnot that are reef safe?

 

[Cassian]

E Marco 400 cement is awesome. it is stronger than the rock itself.

 

[jsker]

Does anyone know of cements that are in local stores such as Home Depot and whatnot that are reef safe?

Most products that are sold from the home improvement stores are designed for home improvements and not reef tanks.

@LukeWolf also made a good suggestion and I have read that the E Marco 400 works well to.

 

[Art2249]

Aquarium silicone works great.

 

[Gregg @ ADP]

Most products that are sold from the home improvement stores are designed for home improvements and not reef tanks.

@LukeWolf also made a good suggestion and I have read that the E Marco 400 works well to.

I was just looking at it. This might be the way I go

 

[Flippers4pups]

Have you ever had any issues with the quikrete coming apart after awhile?

I’ve used rods a bit in the past, but for this project, they might end up being more trouble than they’re worth if the primary benefit is simply to hold the structure in place. I’ll probably end up propping the more adventurous parts up externally with PVC.

It won't if the rock is dry and you use fiberglass rod for structural support.

Any rock structure with cement will need some structural support underneath for the cement to not crack.

 

[Flippers4pups]

Does anyone know of cements that are in local stores such as Home Depot and whatnot that are reef safe?

Quikrete hydraulic cement. Basically the exact same cement that Marco sells. Once cured, no PH swings and doesnt leach aluminum.

 

[Flippers4pups]

Fiberglass rod can be gotten at the big box hardware stores. Look for driveway makers.

https://www.lowes.com/pd/FIBERGLASS-innovations-57-in-Orange-Bounce-Back-Driveway-Reflector/50240017

Use a masonry bit to drill the rock. Cut the markers up into usable pieces.

 

[Be102]

Fiberglass rod can be gotten at the big box hardware stores. Look for driveway makers.

https://www.lowes.com/pd/FIBERGLASS-innovations-57-in-Orange-Bounce-Back-Driveway-Reflector/50240017

Use a masonry bit to drill the rock. Cut the markers up into usable pieces.

I’m just confused on how the rock stays attached to the rods? Do you just drill through a bunch and stack them?

 

[Flippers4pups]

I’m just confused on how the rock stays attached to the rods? Do you just drill through a bunch and stack them?

Stack the rock as you would like them. Take a picture of them. Remove the ones at the top and drill the rock in the center. Try not to go all the way through the rocks. Cut some rod and reassemble them.

Do the remaining rocks the same way till all have some rod supporting them.

From the top down, mix up some cement and remove the top rock leaving the rod in the lower rock. Place the cement on the lower rock and place the top rock on the rod and cement. Shape the cement into the rock and around the joint.

Let cure and repeat.

 

[Gregg @ ADP]

I’m just confused on how the rock stays attached to the rods? Do you just drill through a bunch and stack them?

Yep.

For the biggest structure I’m building, I’m considering using 1/2” PVC. That way I can build a PVC base under it to stabilize it

 

[Flippers4pups]

https://www.reef2reef.com/threads/flippers-reef-125-gallon.317425/

First page of my build thread shows a little of what I did using rods and quikrete hydraulic cement.

 

[Gregg @ ADP]

Quikrete hydraulic cement. Basically the exact same cement that Marco sells. Once cured, no PH swings and doesnt leach aluminum.

If it’s the same, then this is the way to go. $12 for 20lbs vs $40 for 5lbs is a no-brainer

 

[Flippers4pups]

If it’s the same, then this is the way to go. $12 for 20lbs vs $40 for 5lbs is a no-brainer

Yep.

 

[Gregg @ ADP]

Another question:

I have a 3-sided acrylic box (think overflow) that needs to be disguised. I was originally going to have 3 panels made by RealReef, but then when I tried to order them, I was told they couldn’t make them (contrary to what we had originally been sold on).

Do you think that I will be able to just go all the way up with quikrete and then cement in small, thin rock pieces? The bottom 2/3 is going to have a more elaborate rock structure, but I want to be able to hide that upper 2/3 and maybe even build some small shelves onto it (and stick some Monti caps etc on).

Any issues with the quikrete adhering to acrylic? Should it be sanded?