Question on DIY rock

[imchris]

I see where people use portland cement and add an aggregate(I think that's the word) to it like rock or shells. Why not just use concrete which is cement with rock already in it? Is there a difference?

[mahogue]

It depends on how much DIY rock you put in your tank. If you use alot, you want to use crushed coral or old reef rock. IMHO most land based rock contains higher concentrations of silicate, iron, copper and phosphate than we want in our reef tanks. You would then have to remove them with GFO, GAC, CupriSorb and other ion absorbers, makeing the total cost of your DIY rock a bust. You will have to deal with some of these non-reef elements and initial pH and Alk swings because of the cement anyway. Also coral has the correct ratios of calcium, magnesium and strontium when it leaches (thus the use in Ca reactors).

I regret using so much DIY rock in my tank and am seriously thinking of takeing most of it out. I love the perfect custom shape I made, but blame it for my algae problems.

[underwatermonk]

Adding the other substances like crushed coral and/or various sands, will provide a more porous rock. Using just the cement will produce a rock with limited hiding spaces for small inverts and such. I have tried various mixtures from just cement all the way to mixtures of sand, salt, shells and cement. Have made some rocks look like piles of gravel, solid rocks, and am very close to reproducing the look of marco rock. I agree with mahogue, don't use all diy rocks unless you know everything is leached out and reef safe. even then you would probably want some seed rocks.

[imchris]

Well the tank is already established. Just not enough rock though. It's a 210 with only about 75-100 pounds of rock in it. I'm not sure exactly, I just know it's not enough. I'd like to double the amount in there. In fact, when I set the tank up, I put all the rock on 1 side. I knew from the start I needed more. Everything that's in there now it natural live rock. I just thought it's so much cheaper to make your own, why not give it a shot. If it's more hassle than it's worth though, I guess I'll have to pony up the dough and buy some rock. 1 thing I knew I wasn't going to like is the long curing process. Decisions, decisions. Thanks for your help!

[symon_say]

I'm in the process of doing my rocks for my future tank, i have read that crushed coral tend to lead to algae, that's why i use aragonite, curing DIY rock take time, some people have report several months doing it, i haven't test yet mine.

The formula i like to use is 2:1:1 for upper rocks, 1:1:1 for lower/support rocks, salt:aragonite:cement, those formulas give me a really nice rock, light, strong a looks really natural.

Here are some batch:

http://i128.photobucket.com/albums/p186/symon_say/utf-8BSU1HLTIwMTEwNzE0LTAwMDQ4LmpwZw.jpg

[Db366]

There is a DIY video on youtube of a guy making some using rock salt in addition. You would need to cure it for a extended amount of time to get all the salt out afterwards but the final result was amazing.

[symon_say]

There is a DIY video on youtube of a guy making some using rock salt in addition. You would need to cure it for a extended amount of time to get all the salt out afterwards but the final result was amazing.

Curing process is not to take the salt out, salt will go out really fast is to low the alkalinity of cement DIY rock will sky your ph is they are not properly cure.

[wesgentry]

I saw the rock salt done once on a foam back wall and it gives a nice effect. I'm going with a mix of rock from http://www.marcorocks.com/ , rock rubble, and foam for my next project.

[OodleyBoodely]

I used a mix of 1part cement to 4 parts aggregate for my walls. I used roughly equal amounts of crushed oyster shell and perlite for the aggregate. This produced an extremely porous and lightweight rock that I think looks really good. In some areas, I added some aragonite sand and used it like a putty that could be hand molded over difficult to cover spots in my eggcrate structures. I didn't use salt at all and water will literally pour right through this stuff. Here are pics of my cement/oyster/perlite walls. I cured this in tank with just two water changes, but, left it for more than 3 months...I wasn't in a hurry, loll, and had other stuff to worry about. It is currently ready to be set up with salt water now...my next step with my build. :rollface:

[Gandolfe]

also if you don't want to spend a lot of $$$ on rock check out the local pennysavers and Craig's list for people selling off their tanks. I've seen rock on there for less than $2 a lb as compared to $8 or more at the LFS