portland cement for live rock

so i am trying to build live rock. i know that i need to use portland cement. now here is the problem, my local "hardware store" only has portland cement grade 1/2, but i have only read of using grade 2. does anyone know the difference? should i look hard to find strickty grade 2?

 

I believe the 1/2 actually means grade 1 or 2. The grade refers to the use it was designed for. Grade 1 is general use and grade 2 give greater protection to sulfate damage. So any grade should do, some might be more expensive than others though, so I would just go with grade 1 or 2, which is probably what you saw.

 

I would use base rock instead of using concrete, in my opinion! I don't really like the introduction of and use of concrete in my reef aquariums!

 

Good point. I have seen some people do this with good result and its always cool to see the DIY. One thing you should do is check how much cost savings you would really have with making your own vs. base rock too. Keep us updated.

 

I used the same stuff you did and if you look at the 6' long thread, you'll see some of my rock. I love the stuff myself! I make caves and places where I can put corals(holes) and what I've made so far is getting pink! the snails and fish don't seem to be able to tell the difference. as soon as my camera comes back from getting fixed I'll add new pics and show the last pieces I made. I stopped making because I was using my old 55 tank to cure them in and hubby wanted it gone. so, they cured and the tank is bye bye. I never chaged the water and for me it takes about 6-8 weeks for the pH to get to 8.2 which is when I'll rinse it with plain water and put it in my tank....... I've added crushed coral in the past, but I like it with less of that.

 

the bag said grade I/II so i think it was a fixture of both?? but i did find out that grade 2 is used for contact with "soil and ground water" with a higher sulfate content.
And i am making it myself casue i am starting a 75 and base would be way more expensive for the amount that i need. plus i already have the crush coral and a hook up on the sand.
not metion as cutt says it cool cause then i design the cave. also while the rock cures i have time to put toghter my equipment.
thanx guys

 

+1 on gras's comments. When I do my 120 I might go DIY rock depending on how long I want to take with it.
As said before though, it will take a minimum of 2 months before the PH drops enough and you can even think about putting it in your tank