So I collected this bleached coral a number of years ago and it’s been sitting on my shelf for years. I’m starting a 75 gallon reef tank and I was wondering if it’d be safe to use as a rock? It’s completely white btw
HI If this is real bleached coral then you can certainly use it. Coral skeletons are nothing more than calcium carbonate, the same thing we find in base rock that was collected from ancient dried up reefs.
As is true for any dry rocks, you'll want to cure it. Are you aware of the curing process? Since dry rock was once live rock, it is full of dead organics, which is just the dry remains of the critters that used to make it live rock. When dead organics are exposed to flowing oxygenated water, they will begin to break down into phosphates, and possible ammonia, which of course, leads to nitrates. Nitrates, and particularly phosphates are algae's favorite food, so skipping the curing process is what leads to algae gardens in new tanks.ops:
So, some will prefer to do the curing outside of the tank, in large containers with a pump, heater, and saltwater, but no light during curing so as to limit algae growth. The idea of doing it outside of the tank is so a new tank and isn't 'fouled' with algae and the mess that can come with cleaning it. Personally, in our nano 20 gallon with 20 lbs. of rock, we decided to cure and cycle in the tank at the same time. So, during that time the light stayed off, and we mostly just monitored the cycle. When that was close to done and we had done a couple of water changes, we tested for phosphates and found that the rock was indeed cured. All curing is exposing the rock to tank conditions and checking for phosphates and doing water changes when and if they are found. After some time, (could be weeks or months), phosphates will stop leaching from the rock and won't be found when testing the water. When phosphates stay gone, the rock is cycled.
Speaking of rocks and curing, some types of rock will naturally contain more dead organics due to a higher porosity rating than other types of rock. For example, PukanI rock is light and porous while FijI rock, (what I used), is heavier, denser, and less porous. So, FijI will have had less space for life within the rock and thus, will cure faster. The same thing also helps in determining how much rock you need because 20 lbs. of PukanI will take up much more space than 20 lbs. of Fiji. The pound per rule is imperfect because it doesn't take into account how a particular volume of rock might be much heavier or lighter than the same volume of another type of rock.
Congratulations on the new salty tank! We'd love to see a build thread for it and would be glad to help you get started too.