Mr. Saltwater Tank

The Most Common Mistake I’ve Been Seeing Lately


Lately, I’ve seen 2 really nice, established reef junkie tanks come down and both owners made the same mistake.

Both of these tanks had additional live rock added to them after the tank was already up and running and 100% cycled.

What happened next?

Green hair algae outbreaks, mini-cycles, and bleached corals. Oh, then owners then got frustrated and quit the hobby.

If your tank is established, do not add significant amounts of new live rock to it. If you want to add some small (3bs or less) pieces, that’s fine, but any piece over 5 lbs and no more than 10 lbs total should be added to your tank.

Adding “new” of live rock will cause a mini-cycle, nuisance algae outbreaks and cause headaches for you and your tank.

However, If your tank doesn’t have enough live rock (a good rule of thumb is 1 pound per gallon) then add new pieces slowly – 1 piece every 2 weeks.

And if you haven’t setup your tank yet, then plan on buying dead rock instead of live rock. (Read here to find out why). Also plan on buying enough rock all at once so that all the rock can cycle together.

Your tank will thank you for it.

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Comments for this article (6)

  • Ric Johnson says:

    Dead rock is OK then?

  • Ric…adding dead rock should follow the same rules as adding new liverock…small pieces are ok, adding a lot all at once is not so bueno.

  • Jesse says:

    Does this apply when adding dead rock? Can I add dead rock to my existing tank?

  • Jesse..in limited amounts. It will most likely have an algae bloom on it that will pass, but it is still annoying.

  • Dru Carthel says:

    My 55gal has already cycled but i know i dont have enough rock. I just purchased 25 lbs of dead rock and would love to aquascape and put it in my tank all at once in the shape I want. Could I possibly add “One and Only” bactieria along with it to avoid a tank crash?

  • Dru…adding more dead rock probably won’t crash your tank. However, adding Dr. Tim’s can’t hurt.

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