Where are you located?
Have you checked on local and state ordinances concerning collecting local fish, rocks, etc. In most places it's illegal, or highly restricted.
Making your own base rock would make a great class project. Once the rock is stabilized you can add it directly to the tank(s). By stabilized I mean that the pH has stabilized. Cement has a very high pH level and needs to to be rinsed quite a few times to cure the cement and stabilize it. That's not the same curing process as making LR
safe for a tank.
refers to rock that is housing the beneficial bacteria for the nitrogen cycle. So any surface added to the tank will become LIVE over time. Coral rock is very porous so the surface area is greatly magnified compared to any smooth rock.
You can use 70% or more base rock and just a bit of LR
to seed the tank with coralline algae. You could probably buy one or two boxes of uncured LR
, bust it up with hammers and chisels and use it to cycle the student tanks. Of course you would want to have your homemade base rock in the tanks and place the LR
on top of that.