Dried live rock growing black algea.

Mikeand Mel · Jan 30, 2019

Hi all, not sure if I'm in right place but, I acquired dried live rock from a friend who had it siiting on a pallet in his back yard for 2 years.
I bleached the rock and scrubbed it. Then soaked it in RO/DI water with dechlorinator.
After repeating this a couple of times I added salt and a heater to the 55gallon drum.
After 2 weeks I put the rock in a 40 gal. added a dead fish from my display.
Also, added 3 large pieces of a leather coral I fragged out of the display(killing many of the fish in that tank).
Leather frags look great. Some stringy algea, and now tops of rocks are turning black,
What should i do next?

ihavecrabs · Jan 31, 2019

Depending on how far along your rock cycle is, I'd almost pull the coral out and remove the light source, unless it is already in your display.

Have any pictures of the rocks turning black?

redfishbluefish · Jan 31, 2019

The rock has not had sufficient time to cure. I'm not talking about the cycle, but about the time needed for the old dead stuff in the rock to completely break down and leach out of the rock. This is a typical problem with new folks who don't cure and then wonder why they have high nitrates and phosphates and algae growing all over the place.

Dependent on how "dirty" the rock was, curing typically takes one to two months. What also typically occurs during this time is the cycle. What you need to do are water changes and measure N's and P's (or just one of them). You continue doing water changes (maybe weekly) and testing until you see the N's and P's drop way down. The cure is now done.

For curing, the only thing you really need is a little water movement and saltwater. Heating (assume done in a heated house), light and skimming is not needed.

Hope this helps.