best concrete for DIY rock

does anyone know the best kind of concrete for diy rock?i just wanted to make sure before i bought the wrong one this weekend. im looking more the lighter color concretes so if anyone has any input please inform. ;D

thanks

 

Not too sure on that but I know there are a few on here who have done DIY rock. You can use the search bar on the hompage and you should get some info.

 

yea i tried and no one posted the brand or do not use this product info on it. just want to make sure i dont do harm in the long run when i do this.

 

Portland Type II cement.

 

Just make sure its cured before you place it in your tank.;D

 

thanks yea i was planning on curing the rock in the tank on a temporary stand in the garage before i got my stand. i figured i would get the stand by the end of november and actually set it up by january time frame.im hoping thats my timeline so far.

 

The color of your concrete is going to be a function of how much cement you put in and how much water you supply it. Also the sand aggregate that you use will make a large difference in final color. A fine masons sand should give you lighter color. With Portland type II more cement gives whiter concrete. Portland type II usually takes close to 120 days to become completely hydrolyzed but this process can be sped up by placing the concrete in a slightly acidic to neutral tub of water. This then cuts the reaction down to about 60ish days.
If you can get ahold of Portland type IV cement the 100% hydrolyzation process is cut down to 4 days under normal conditions. However, type IV cement is hard to come by and is outrageously priced.

 

Doesn't concrete leak bad things into the water? Last time I checked you couldn't use any sand with concrete in it because of this...

 

During the hydrolyzation reaction it pulls H+ in to bind to the cement. This then in return causes an increase in OH- in the surroundings. This is the reason it is best to cure in water before putting it into your tank.
The concrete itself does not release any chemicals.

 

White portland cement. Its like $20 for 100 lbs