Concrete for attaching rocks?

[Adam]

I was going to buy some mortar from Marco but I was wondering if concrete would work. I bought a 10lb box of http://www.ctscement.com/wp-content/uploads/2014/02/CEMENT_ALL_Datasheet_DS_024_EN_2.pdf">RapidSet Cement All</a> from HD to put under a couple spots on my stand that I can't get to with shims. The stank had been shimmed and 220 gallon tank filled 3/4 full for 5 days. After the initial adjustments it's held level the whole time. The spots I can't get to are in the front corners where the stand meets the wall. So today I figured it was time to get that taken care of. This stuff mixes nice and and doesn't shrink as it sets. I made what I mixed on the thick side and it worked really well. Setup in the stated 15 minutes with no sag out.

Would this work as a mortar on rockscapes? It looks just like the bag on Marcorock's site and costs $10 at HD. I've got most of the box left over.

 

[sewer urchin]

In the past I've used Hydraulic Cement to piece together several chunks of drilled live rock (drilled and then a fiberglass driveway marker peg to hold it together until the cement hardened in 15 -20 min.)
I think that the big issue with cement is that it is a bit caustic (high pH) as it cures and that could take several months. With the hydraulic cement, I used about 5 lbs on about 70-80lbs of rock for a central structure and had no pH shift in the 120 G. Didn't seem to have any effect on the corals either, although they were the more hardier types like a Green Slimer Acro, zoas and GSP.

If you are on the fence about if it might work, I would mix up a couple of small samples and put them in a 5 gallon bucket with water and take a look at the pH, if it spikes high I would stay away.

 

[snowmansnow]

hey Anit, for what its worth heres my limited experience.
1- avoid using ONLY cement / epoxy to attach your rock together, especially if you are connecting overhangs and so forth
2- if possible drill the rocks and use acrylic rods to carry most of the load of the rocks
3- if possible use a BIG rock and simply carve out the shape you want... use as few rocks stacked on top of each other. (BRS does a good job of sending CHUNKS of Pukani that is big enough to carve)
4- make several "sections" of your aquascape that is independent . This allows you to remove certain rocks for maintenance / rearrangement without upsetting the entire aquascape

again, my limited experience

 

[Adam]

If you look in my build thread you'll see the scape I'm planning. It's pretty minimalistic and I'm thinking of just using a little in places to add some stability. I do want to to keep it pretty modular too, so it's easy to make changes .

 

[Adam]

Thanks for the info on PH and using rods guys. This will help.

 

[torqued]

If you can wait, I almost certainly will have extra Marco cement. I bought a large bucket of the stuff. How soon do u need it?

Sent from my Nexus 6 using Tapatalk

 

[Adam]

I'm planning on getting the plumbing done and water testing the system by the end of the week. If all goes well with that I plan on getting the scape installed this weekend and filling it up.

 

[bulkrate]

For smaller, fine-detail work (say 2-3 fist-sized rocks or a non-involved scaping) WaterWeld epoxy does a decent job, but you have to zip-tie/brace/clamp together whatever you're sculpting or it'll form a poor bond or mushroom out of the seams. Also, do yourself a favor and scrape away as much of the squeezed out residue from the joins as you can before it sets.

Main reason I've used it is that it's rated drinking water-safe & it's readily available at Lowe's/Home Depot.

if you cure the joined bits in the tank, your skimmer MAY go nuts for a day or two. I've found that it works better if you can let the stuff set & cure dry.

 

[johnqx4]

Not sure that I am answering the EXACT question. However, I have made many different types of "reef" rocks for aquascaping. I have used several types of cement. Straight portland is probably the best, but you usually have to buy 80lbs or so (it is cheap, but just a lot to hang around or throw away).

However, having said that, whenever I make something out of cement, i leave it out on the porch (in the weather and rain) for a month or so before I put it in the water (usually more). But then again, I'm a patient guy (and cheap

With that, I have never had any problems. But for 99.9 percent of the folk (who need quicker results) that probably won't work. Marine adhesive has always been my "quick" friend.

Just my $.02 worth

johnny