Live Rock,…it’s what?

By: Kevin | April 20, 2011

The Rock

I know what you’re thinking. How can rock be alive? That’s the first thing I asked too. Well I’m here to tell you that the rock itself isn’t actually alive–it’s what’s ON the rock that is. There are millions of micro algae and some macro algae, invertebrates, etc.  The algae is the essential part of the tank because it provides a diverse eco system. Most importantly the algae is the tank’s main filtration system. Millions of these little guys break down waste (ammonia, nitrates, and nitrites). The waste comes from a number of things, including fish waste and over feeding.
Green Macro Algae


Where to get rock?

After searching all of the local pet stores, I discovered that cured live rock would cost me an easy $7/lb.  The suggested ratio is 1-2 lbs of live rock per 1 US gallon. Since I’m setting up a 55 gallon tank, this was going to add up in a hurry. 55 x $7 = $385. Ouch! Aside from being out of my price range, this option would be the easiest since the seller has already ‘cured’ the rock and it would be ready for my tank. There are many sites out there where you can buy live rock and have it shipped to you. I was a bit speculative of this option.  I can’t drop $7/lb for my rock so I ended up ordering from I ordered 50lbs at $3.50/lb = $175 AND free shipping. operates near Miami, FL. Their site was quite plain, but effective.
My order showed up and needed a lot of TLC. The rock was very silty and had lots of undesirable macro algae on it.  All the stuff currently on the rock I DON’T want. The algae isn’t bad but it’s not as pretty as the corals I will be getting, so I need to clean off all the algae.


The Curing Process

The rocks I purchased were cheaper because I decided to cure them myself. Time–I have, money–I don’t. Since the rock was shipped via FedEx ground, it had been somewhat damp for a few days, but was not completely submerged. This caused some kill off of bacteria.  Kill off = Ammonia, so much ammonia that multiple water changes are needed to assist the surviving bacteria that can’t keep up. Since the rock is no longer in the ocean, mass amounts of water can’t dilute the ammonia. The killed off bacteria spark the remaining bacteria to multiply and consume their waste (ammonia buffet). The ammonia level gets so high during this time that it would be fatal for any fish or coral. This bloom and kill off of bacteria can last anywhere from 4-6 weeks

First scrub. I scored a lot.

So to sum it up, I need to ‘cure’ the rock and let the bacteria runs its course to stabilize to a point of equilibrium. I am changing the water once a week to help speed up the process and lower my risk of complete kill off.  I put all the rock in a Rubbermaid 25 gallon storage tub.  I chose not to cure it in my tank because that would require a lot more water and sea salt. Remember I have time, not money.

Take a look at my first curing water change with notes explaining what I’m doing.

REMINDER: Always unplug your aquarium heater when doing water changes. Allow your heater to acclimate to the new water temperature before plugging it back in. I pulled a rookie mistake while making the above video and plugged in my heater too soon. Not only did I take 120V but I busted my best heater.