So I am growing some fantastic GREEN coraline algae. I lost a lot of my purple/pink coraline when I moved the tank. Than I had a baby and did minimum maintenance for a year (bad tank owner).
So my rocks have a fantastic purple/pink color. The back glass is entirely green. WTF? Everything is very healthy and I'm pleased. Should I care? It just seems weird that it is green where as before it was pink/purple.
Thanks Folks
Tank params
125 gal
6x96watt pc 10k/acentic
20% water change weekly
1 gallon kalk drip weekly
1.24 sal
alk 13
phos 0
nitrates 0
nitrites just detectable


Active Member
I made some changes in my tank several months ago, most of the coralline on the back wall turned and then over time turned green. Nothing to worry about as a matter of fact some of the green is now turning back to the purple. Sad because I like the green. Just sit back and enjoy it.


Active Member
Here is one explanation I found when it happened to me and is certainly what probably was the cause with me. I had all the water out of the tank along with the rockwork when I took our the substrate to go bare bottom but the lights were on the whole time.
After a water change, sometimes the corallines bleach in a perfect band down to where the water level had dropped for the WC. Some folks naturally think it was the air-exposure... but that is not the case (consider that you got your corallines from live rock shipped dry and exposed to air for days). It is the water change under bright lights (always turn light off here) that exposes the corallines to a sudden increase in light intensity no longer tempered by the density and depth of the water they grew under