reboot reef tank

A Blueprint For Rebooting a Reef Tank

Does it make sense to tear down a thriving, healthy reef tank? On the surface it would seem to be a foolish move but a tank with too much coral growth can spell trouble. Growing corals can cause a drop in circulation and make it easier for detritus to settle inside a tank. This can lead to problematic algae such as cyanobacteria. Less circulation will also make it harder to deliver nutrients to corals.

This was the scenario I experienced with my 187 gallon SPS dominant tank. It was started about five years ago and certain colonies were taking over a lot of real estate, crowding and shading out other corals. Some cyanobacteria was present, although it was at a manageable level.

Tank at Crossroads

Repeated fragging worked for a while but it became less and less effective over time. Some corals were succumbing to Slow Tissue Necrosis (STN) at or near their bases due to a lack of light and flow. The tank was at a crossroads and I couldn’t believe I was contemplating a re-do of this gorgeous reef.


The aquarium was started with 125 lbs of Haitian live rock, which was now completely covered with encrusted coral. Could I remove the encrusted coral and reuse the rock? Yes, but I wanted to utilize dry rock to create a more open aquascape.

A fellow reefer used CaribSea Life Rock, mostly arches, to redo his reef and I thought it looked awesome. Epoxy, super glue and super glue accelerator were all used to create a very open and unique structure. My plan was to mimic his design. My first experience with dry rock was not good. I didn’t add enough bacteria when the rock was put into the tank and it resulted in one problem after another, including dinoflagellates, cyanobacteria and diatoms.

New Plan For Introducing Dry Rock

This time it would be different. The plan was to “cook” the dry rock in established tank water for a few months. This would give bacteria plenty of time to colonize the rock. I had a 100 gallon Rubbermaid tub in storage so I pulled it out and filled it with some newly mixed saltwater and water from my 187 gallon reef. Once the aquascape was glued together I put it in the tub and added some power heads and a heater. That was it in terms of equipment.


Each week I did a 10% water change with water from my 187 gallon tank. I also added Brightwell’s Microbacter 7 bacteria on a daily basis. Would there be enough bacteria on the cooked dry rock to replace the bacteria I would be losing when I removed the Haitian live rock? Perhaps, but I didn’t want to take the chance.

Goal: Coral Preservation During Reboot

What was at stake? Well, I had ten SPS colonies in the display I wanted to transfer to a 75 gallon frag tank plumbed into the display. I also had a bunch of frags in a 50 gallon frag tank that was also connected to the display. The goal was to preserve all of these corals.

My plan was to keep the Haitian rock in the system by adding it to a cryptic sump. I picked up a 60 gallon polyethylene tank and plumbed it into my main sump. Light would not be able to penetrate into the tank since it was black and had a black lid.

While the dry rock was being conditioned I took my time removing the colonies from the display. One or two were removed every week or so. After cooking the dry rock for six months I decided it was time to put it in the display and pull the Haitian live rock. There was one hitch. Part of the sand bed in the display tank was calcified. During the rock swap I wanted to remove the calcified sand but not the rest of the sand bed.

Disturbing a sand bed can be problematic since unwanted toxins can be released in the water and negatively impact fish or corals. To play it safe, I decided to do this part of the project in two phases. During the initial phase I removed one island of rock and the surrounding calcified sand. Two weeks later I removed the second island and the rest of the calcified sand.


During each phase, a lot of detritus and other gunk went into the water column when the rock was removed. I tried to let most of it settle in the display by turning off the return and recirculating pumps for a few hours. The water was mostly clear a few hours after all the pumps were turned back on.


So how has it been going? So far so good. No coral losses after two weeks. As expected, my alkalinity spiked a little since a lot of coral that had encrusted on the rock was removed from the system. Nitrates and phosphates also went up a bit since there was less coral to consume those elements. More cyanobacteria did pop up in one of the frag tanks and some cyano has reappeared in the display. The plan at this point is to wait two months before adding a bunch of SPS frags. This should give the tank enough time to work through any ugly phases.

Phew, this was quite a project and I am glad it’s in the rear view mirror. But as is the case with many things in reef keeping, patience and careful planning will usually be rewarded with good fortune.

Additional Resources

If you would like some help with a new tank build, including help designing a custom aquarium, or help re-configuring your current setup then you can visit this page for more information. And if you are looking to add some equipment, I do sell GHLPax BellumReef Octopus Calcium and Kalk Reactors and Royal Exclusiv products, including Dreamboxes, which is the equipment I use and recommend. I also sell Reef Brite metal halide and LED fixtures as well as Maxspect & IceCap Gyres.

As for additional insights and information, please explore my many other reef tank and SPS related articles as well as my YouTube channel. For an even deeper dive into reef tank care you can check out my Reef Keeping Master Class. This online course is an immersive and one of a kind educational tool designed to help reef aquarium hobbyists build and maintain a beautiful SPS reef tank. The course is a series of video presentations with some supplemental video from my YouTube channel. There are also quizzes to help students retain and understand the information presented in the course.

Need some frags…..I can help with that as well 🙂 Please visit my SPS Frag store to see what is available.

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