Ok. Following on from my previous post some developments. Lots of red slime on my sand, which from reading is the bi-product of the bacterial action of cyano bacteria. I'm scooping it out with a net, rinsing the sand thoroughly until its all washed away before returning it. Phosphates have now dropped right back again, and curiously the skimmate has lightened considerably from it's previously near black colour to light brown, which would suggest less organics? So, if the cyano bacteria seems to be increasing judging from the red slime, why are other parameters showing improvement? Also, on a good note, the pearling is decreasing since dropping back on the light intensity. I can see gases being released when I gently stir the sand which I'm presuming is nitrogen? So, my confusion is how best to rid my tank of it. I have read about shop bought preparations, and the impact the die off can have, same thing with erythromycin, which attacks the bacteria but also destroys beneficial bacteria, all impacting negatively overall. I'd like anyone who has first hand experience of cyano to share that, and if possible give some guidance on how best to firstly get it under control, and then eradicate it. Thanks in advance.