Readying Old Rock for New Tank
Last fall, when getting ready for this new tank, I was not sure if I would need my old rock, so I processed it just in case, and have now decided to use some in my refugia as homes for bacteria, pods, sponges, etc.
The rock in my old tank came from multiple sources. The initial rock came from TBS in the days of wild rock collection. I also won a full setup in a raffle at the 2004 MACNA, and it had what I assume was Tonga branch rock. Later I got some big pieces from Walt Smith when the tank upgraded to 120 gallons.
When I took the tank down, much of the rock was donated to the Boston Reefers for one of their fund raising auctions. For reasons I cannot recall, some ended up just being placed on the ground out behind the garage. I’m not sure what the original source of this left over rock was, but it may be from all of these sources.
When I went to look for it, some was literally buried under soil. Other rocks were covered in moss. Clearly, some work was needed to use it.
First step after digging it up was to hose off as much dirt and such in the driveway:
It was a pretty good amount, about half filling a 44 gallon brute can.
There was clearly a lot of non marine bacteria and other organisms on the rock. Since I was in no rush to use it, and since I did not want these bacteria contaminating the tank, I added a large amount of bleach (maybe 1/2 gallon of cheap grocery store bleach) to the Brute along with tap water to cover the rocks. Too much bleach, as the basement smelled strongly even with the Brute lid on and holes in the can plugged.
After several days, I removed each rock one at a time (with gloves), rinsed it for maybe 1-2 minutes per rock under a strong stream of cold tap water in a basement sink. Way too much bleach smell. If the weather were better, I would have done it outside.
Each rock then got a few minute soak in a mix of food grade ascorbic acid in water to neutralize the bleach. Maybe a cup of ascorbic acid in a few gallons tap water in a salt bucket. The usual dechlorinator would likely have been fine, but I wanted to try this.
Each rock then got a final tap water rinse and was stored on an open shelf in what would become the fish room, ultimately drying out over several months of the winter. They smelled faintly of bleach for a while, likely from bleach deep in pores, but that faded over time and certainly none remains now several months later.
Yesterday, I took several of the largest pieces and placed them into Brute #1, where 3-4 new tbs rocks also now reside. I moved some macroalgae from Brute #3 (the current refugium Brute) and set it up with a single led light shining into these new and old rocks plus macroalgae through a hole cut into the Brute lid.
I may also add more old rock to Brute #3, effectively putting rock at the bottom and macroalgae on top of this more brightly lit Brute. I’ll make that call after seeing the remainder of the new TBS rock. :)