There is really no easy solution or one that does not have its own drawbacks. While undectable phosphates/nitrates seems to be the standard answer, it is not entirely accurate simply because phosphates are in everything that was (food) or is alive (pets) and that phosphates bind to calcium carbonate (rock/sand), meaning that even if it was possible to get absolutely zero phosphates in the water (which would be a bad thing anyways, but a different topic) the cyanobacteria are able to alter the pH of the porewater directly underneath them thus releasing the phosphates for use, some of that same cycling of binding and releasing also happens within sandbeds but tends to find an equilibrium in due time.
As much as a pain in the butt that it is, the only real solution(s) is to increase your water flows over the calcium carbonate rocks/sand and brush off / siphon off the cyanobacteria that you can reach. That and include competition for those nutrients in the way of
an Algae Turf Scrubber and/or
a macroalgae refugium (preferably both if possible).
Other "remedys" be it altering the environment (light reduction?) or anti-bacterial agents are simply not going to last long and just create a short lived temporary reduction leaving you to have to deal with it over and over again.
But, with that said, once you have an alternative consumer (algae) in place, I have once,
and only once used Eurethromycin (pills) (same stuff used in "slime away and other such products but costs me 50 cents a pill) at a rate of 250mg (one pill) per 100 gallons of water which killed the cyanobacteria over the course of a few days and then ran carbon to remove it. While it solved the immediate problem, I knew I had to have something else in place to deal with it long term (ATS/Refugium) and it did the trick. I really hated having to do so as I also noted the loss of a great many other life forms in my system although it had no effect on my corals or fish.
Chuck
Quote:
Originally Posted by biocube14  Help chuck! I have purple cyanobacteria all over my live rock. Read lots of remedies, but looking for your advice! 14g biocube, 2 clowns, fireshrimp, 2 turbo snails, condy anemone, 6 nano shrooms. Tank is 3 months old, water tests good, phosphate is near 0. 24 watt 10,000k daylight on for 8hrs. and 24 watt actinic on for 10hrs.  |