Just did another big rock tonight and this time I did a old school mix and then folded in a bunch of solar salt. I am going to let it set for 4 days instead of my usual 1 to 2 and then pull it from the mold and see what I get. The last 2 rocks I did I used 6 3" tall cardboard tubes spaced out in the tub and then filled up the tub with solar salt to the 3" depth/height of the tube, and then filled the cardboard tubes with cement, then built the layer rock on top of the 6 piers. I am planning on 3 or 4 of these for a base of the rock pile to get it off the tank bottom.
The Ultimate DIY Rocks!
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GuySmilie
Premium Member
Actually, after I wrote about this, I got to thinking about what I had wrote. It looks like I've juxtaposed 'thought processes' from one thread to another. Is that possible on RC - what with following 50 threads at a time?
What I was really flirting with doing is to cut a piece of eggcrate to the dimensions of my rear tank wall, minus a 1/2" border on the sides. Then play around with the expanding insulating foam sprays. I had thought about using Great Stuff or one of it's clones by DAP, etc. While visiting a pond shop the other day, I saw this black foam that looked intriguing, but at $16/can I got over it.
Anyway, I plan to lay down this eggcrate on a clean level surface and start developing a layer with the foam, building it up heavier near the bottom of the eggcrate panel, then tapering the overall thickness as it approaches the top of the panel. This way when it sits in the tank, it will be a bit more stable, as it will have more mass near the bottom. But the bottom would still be no thicker than 2-3 inches at the most, while the upper area will be just thick enough to cover the grating of the eggcrate.
So once I get some interesting forms and shapes sprayed on, I will use a small trowel, or chunk of sponge, or whatever, and shape and smooth it out until I get it into a profile that I like. Then, after the whole thing has completely cured, I will check for fit in the tank, carve out any recesses for bulkheads, etc., maybe carve out a few pockets for frags. Then, after I finally get it looking like something I like, I'll make up a batch of cement (probably pretty loose, since I'm not looking for shape anymore), then skim coat the entire panel with a few layers....until I think it's got enough on it to withstand the rigors of tank life.
Then I'll let this all cure the required timeframe for cement, trim any edges that don't fit the profile of the tank correctly, then silicone glue it to the rear of the tank.
My rationale here is to have better control over the shape and texture of the wallscape, as well as reduce the amount of weight, compared to building it with solid cement.
Another advantage (at least to my way of thinking) is that with a fairly dominate wallscape such as this, there is not such an urge to fill in the open space between the rear and front of the tank with free standing rock. Maybe several choice pieces, but nothing like the huge piles I see in a lot of tanks.
And final justification (which Travis got me to thinking about) is that if the day comes to take the tank down, the bond to the glass will not be cement to glass, but foam to glass...which would lend itself to total removal, with a bit of elbow grease. Just some rambling thoughts....
Guy
Travis L. Stevens
Active member
Don't forget if you have a center brace in your tank that the back wall will have to be in two pieces in order to get it in the tank.
Insane Reefer
New member
Day 8
Day 8
This is now day 8 of the "MMLR Growout Experiment", lol.
My camera is washing out the backwall, if I do a whole tank pic, so today I included a closeup of the wall.
Diatom is dying off, green algae is starting to skim the rock, and have several spots of red showing up - not sure if this is red coralline, cyano or "other" at this point.
And Guy, this shows how one can deal with "seams" in a panelled back - with very little effort, it can be made to look somewhat like a crevasse...
Day 8
This is now day 8 of the "MMLR Growout Experiment", lol.
My camera is washing out the backwall, if I do a whole tank pic, so today I included a closeup of the wall.
Diatom is dying off, green algae is starting to skim the rock, and have several spots of red showing up - not sure if this is red coralline, cyano or "other" at this point.
And Guy, this shows how one can deal with "seams" in a panelled back - with very little effort, it can be made to look somewhat like a crevasse...
zachtos
Active member
Has anybody compared the weight of this DIY live rock to standard figi live rock to see if they are similar weights per volume?
I'm planning to make 300-400lbs this weekend with friends using 3 parts morton system saver 99.5% salt and 1 part portland type 3 cement and 0.5 parts quickcrete sand. I'm not too concerned with pretty shapes since it'll be all in my 150G and 100G sump for the majority. I have 175lbs of dead live rock sitting in a trashcan waiting for me to start my 240 and 75G displays.
I'm also thinking of making my background on the 240G out of greatstuff foam and painting it with colored concrete. I won't be able to cure it under water other then misting it. Do you think this is a problem considering how thin the cement should be volume wise?
I'm planning to make 300-400lbs this weekend with friends using 3 parts morton system saver 99.5% salt and 1 part portland type 3 cement and 0.5 parts quickcrete sand. I'm not too concerned with pretty shapes since it'll be all in my 150G and 100G sump for the majority. I have 175lbs of dead live rock sitting in a trashcan waiting for me to start my 240 and 75G displays.
I'm also thinking of making my background on the 240G out of greatstuff foam and painting it with colored concrete. I won't be able to cure it under water other then misting it. Do you think this is a problem considering how thin the cement should be volume wise?
Insane Reefer
New member
Zach, what is your avatar an picture of? Looks sort of like a LED array - if it is, please PM me - I am interested in LED and would like to chat, if you've a mind, and I haven't mis-seen your pic.
And the cement:salt rocks are very light weight in comparison to pretty much any true live rock, if my test pieces were any indication. Travis says he has made floating rocks before too. Your rock will weigh approx what the sand, cement and water weigh total, plus another 10-20%. That 10-20% is leftover salt, I think, that has bonded molecularly, and remains part of the rock.
And the cement:salt rocks are very light weight in comparison to pretty much any true live rock, if my test pieces were any indication. Travis says he has made floating rocks before too. Your rock will weigh approx what the sand, cement and water weigh total, plus another 10-20%. That 10-20% is leftover salt, I think, that has bonded molecularly, and remains part of the rock.
Travis L. Stevens
Active member
While I have no true way to tell what the outcome of the weight of the rock will be, I believe that Insane Reefer is probably guessing right on the money there. FWIW, if someone was to do a weight comparisson, make sure that the rock is completely dry inside and out. This means killing a piece of live rock. But, you won't have the weight of the water effecting it.
Also, if it is any consolation, everyone that I know that has ever handled my rock have all said that it was far lighter than the real stuff. I'm sorry that I don't have any extra rock at the moment to see if any of it floats, or to compare the weight to real live rock. If I do later, I'll take pictures and record my notes. I do plan on making about 100-150lbs of rock for my 75g as soon as we move.
zachtos
Active member
you could always do a simple test for me without killing it.
you can scientifically calculate the density. Just displace water and compare weights.
example:
1. weight the live rock
2. place the live rock in a bucket, measure the raise in water level, calulate that volume.
3. divide the numbers to get density
do the same for the created rock, you may have to wait a while for the water to infiltrate the pores completely to get proper density.
*this measurement can be used to give the rest of us an idea of what % the weight to volume difference is vs. natural rock. and it's easy to do.
I think you mentioned I need to just count the volume of the salt basically to determine the volume of live rock I'm going to create?
you can scientifically calculate the density. Just displace water and compare weights.
example:
1. weight the live rock
2. place the live rock in a bucket, measure the raise in water level, calulate that volume.
3. divide the numbers to get density
do the same for the created rock, you may have to wait a while for the water to infiltrate the pores completely to get proper density.
*this measurement can be used to give the rest of us an idea of what % the weight to volume difference is vs. natural rock. and it's easy to do.
I think you mentioned I need to just count the volume of the salt basically to determine the volume of live rock I'm going to create?
Travis L. Stevens
Active member
I didn't think about doing it that way. I'll have to see if I can do that tonight. I have a single piece of DIY Rock that isn't in an aquarium right now. I'll see if I can do that tonight if I can get scales that read in good intervals. Mine is digital and reads in .5 lb intervals 
Insane Reefer
New member
Hey Blake, consider making a cover for your overflow - you should be able to make it blend in with the pillars you already made.
Good Job
Good Job
Travis L. Stevens
Active member
Zachtos: I apologize for not having any results yet. I got really busy yesterday, but I did manage to get some better scales. Now, here is a question for you; should the units of measurement be in Metric or Standard? Or will it make a difference?
speckled trout
New member
Some water will remain in the rock before you place it in the "bucket" to measure its displacement. When you place it in, you won't be able to account for any water that was already trapped inside. You'll have to make sure that all of the water has evaporated from it before this will truly work. Thus, a "dead rock".
Travis L. Stevens
Active member
I planned on using dry rock weight first, before measuring displacement. When I measure displacement, I'll make sure to let it soak for a while, possibly an hour each, before measuring displacement.
zachtos
Active member
as long as you record the unit of weight and volume, I can convert it later. What I really want is just a rough percentage difference vs. traditional figi rock...
...say, our DIY salt rock weighs 50% less for the same volume, so you only need 0.75lbs/gallon instead of the usual 1.5lbs/gallon.
I doubt the tiny difference in water entering the pours will matter, the BIG difference is just getting a rough idea of the weight vs volume, this doesn't have to be super accurate, maybe +/- 15% is good enough for our uses.
...say, our DIY salt rock weighs 50% less for the same volume, so you only need 0.75lbs/gallon instead of the usual 1.5lbs/gallon.
I doubt the tiny difference in water entering the pours will matter, the BIG difference is just getting a rough idea of the weight vs volume, this doesn't have to be super accurate, maybe +/- 15% is good enough for our uses.
Travis L. Stevens
Active member
I like this form of measuring and comparing and I can't wait to see the reults, but I don't think the results will show that any more or less rocks per pound will help with effective biological filtration. The density of the rock itself might cause it to weigh more than another, but that same rock might be more porous to allow more surface area for bacteria to grow.
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