FuzzyZipperbaum
New member
Yeah the rock really came out well. Though making over 1000#s saved some money...I didn't do it for that reason. As with this build I just like the DIY route and thought this was something I could pull off. If you google DIY live rock you will get a ton of threads. videos and articles. The GARF instructions are what most start with.
My thoughts: I tried every type of combo you can come with...sand, oyster shell, small lime rock, salt, perlite and of course concrete.
Ill start with the only thing I would change...the cement. Most everyone calls for Portland type 1 or 2. In Nineballs thread (one of the great modern threads)...Mr. Wilson (who is beyond a wealth of information) references a special underwater concrete that is LOW in phosphates. Portland will have high phosphates that you will have to leach out over months....
The most important thing on the mix is the water content. Whatever materials you go with if you miss on the water, you miss on the rock. Most of my rock is approximately 4.5 parts material to 1.5 cement. On rock that is 4.5 to 1...it is lighter but is more brittle for the first month. My suggestion is that the longer you can leave the rock alone to dry, the less concrete you will need to bond it. The less concrete, the lighter.
My favorite basse mix was either crushed oyster shell (you can get this at any feed store) or crushed limestone. I ended up using the limestone twoards the end because I could buy it by the yard. I used 2 parts of the above, 1 part rock salt, 1 part perlite and approx. 1.5 parts cement. I tried all kinds of combos...no rock salt, added sand...added all..... again, in the end..water content makes or breaks you. So some of the rock was 2 parts shell, 2 parts rock (or 2 parts perlite) and the concrete. I saw very little difference in the outcome but I always like the thought of the rock salt dissolving over time and leaving small voids in the rock structure....
I put everything in a wheel barrel. However, I always added the concrete last. Here in Florida with the humidity, if you put the concrete in first it would stick to the sides of the wheel barrel making it harder to mix. Mix everything BEFORE you put water in....I used a shovel and my gloved hands. Add water slowly and mix...over and over. My best suggestion is to have a bucket of water next to you. As I got down towards the end. I found that I put too much water in with the hose but could put exactly what I wanted with the bucket... Remember to add a little water each time...because it will look like you are really short on water and you only put a few ounces in and that becomes too much.
The mix you are looking for is dry oatmeal. You basically are just trying to coat the concrete with water so that is bonds everything. If the mix is too wet, not only with the rock be weaker, it will be heavier. Have some of the perlite or rock salt ready in a bucket if you add too much water to soak up the difference.
I commandeered my kids sand box for the forms. I would make all kinds of sand indentions.....like 3 areas that were 12" down for the legs...and would gently place the cement in the forms. Don't drop the cement or it will compact...place it in... Then I would put sand over the wet concrete in different areas to give the rock caves, movement, etc. and continue to build. Always make sure that at any point that you are using sand to cover the cement that at least one part of the cement is always touching somewhere.
I made mostly "show pieces". These were large pieces that could stand on their own...lots of movement, caves, etc. Smaller pieces were made with either left over mix that wasn't enough to do a large piece. OR.... a large piece that came out boring...then a hammer made it into smaller pieces. You can get a ton of inspiration by looking at aqua scape pictures here on RC...then try and duplicate them....oh and if you have kids...they make great rock because they just throw it around and it seems to always look good.
After the mix was in the forms for about 30 minutes. I would take long drill bits and poke holes all over the mix. remember that most of the structure is under the sand at this point...so you need long bits. Poke holes all over, some holes will close...some will chip something off...etc. If you wait too long to poke holes....the mix will sometimes come apart by poking holes in to it.
Every 24 hours for 3 days I would wet the mix with water. I then put a shovel under each rock and pop them out of the sand on the 4th day. If you try and take the rock too early, you risk breaking it. I would line up all the rock and water it every 24 hours for 30 days. The more you wet the rock the faster it cures and the stronger it gets. Concrete is said to fully cure after 30days but that is not entirely true... Concrete always continues to get harder over its life....but 30 days is what you need to wait.
I then placed the rock into Tampa Bay (something that not every will be able to do so obviously skip this step). Everything in the rock mix is basically found in nature and in the ocean, so I was not worried about polluting the water. I found over time that in one area I put the rock it got very little sea growth and yet 10 feet away I got a ton of oysters, barnacle's, etc.... Mother nature took care of curing and phosphate control for 6 -10 months. I have been planning this build for 2 years so the rock kept me busy while I was planning. The last stage was to pull the rock, bleach it for 3 days...let it air dry for a week...and the put it into Rubbermaid bins to cycle it..... they have been in there for about 6 months.
I will try and dig up some pics later...hope this helps. I am sure I left out some things but there is a tone of info out there including a video on utube where a guy is building some rock in a kiddie pool and his wife comes out to yell at him for something he did....lol
