when did you set this up, test and add the livestock? It all seems far too soon to me.

Even if you used established water, rock, sand etc...the tank still has to stabilize...if anything you just cut the cycle time down by utilizing established water and rock.

Not to be rude, because I'm only trying to help...but if you are asking questions about what temp should you run the tank...then that tells me you should not be adding livestock yet. Livestock should not be added until you are certain you have cycled and you are running a stable system.

I did the same on my 29g biocube...I used established, rock, water and sand but I still had a cycle and did not start adding livestock for a couple of weeks. Seeing cyano is a good indicator that you have cycled.

If you have an established 125 up and running that can support a nem and clownfish then I urge you to add the livestock to it. At least until you get things stable on this system.