Iron dosing causing cyano?

skr791346 · May 13, 2019

I started dosing ESV Transtion Elements a few months back and I'm starting to notice rapid spread of green cyano on my sandbed and rocks. Can Iron dosing cause cyano or is another factor causing it? Dosing 7.5ml daily for 150 gallons.

NO3 5, PO4 0.02, last ATI ICP test showed Iron at undetectable.

Ron Reefman · May 14, 2019

Why are you dosing ESV Transition Elements?

Iron is typically dosed to help with macro algae growth. Are you sure what you have growing is green cyano bacteria?

skr791346 · May 14, 2019

I'm running an ARID reactor w/ chaeto to help with phosphate & pH. I'm almost certain that it's cyano, I'll take a pic of it shortly. Below is a pic from google search "green cyano" but it's identical to this look, except it's starting to cover my sand and rocks as well.

lapin · May 14, 2019

I too think green cyano (spirulina), growth is fueled by the addition of iron. I had the same issue on my sand. I stopped dosing iron and it is slowly going away. Hopwever it had no effect on the red cyano that I noticed.

AdamNC · Sep 21, 2020

Bump.

Any update on this or has anyone else noticed the same effects? I just recently got a Pax Bellum N18 to help with nutrients, it came with a bottle of Iron+Manganese and now my tank has exploded with Cyano.

Last test I was at No3 32ppm and Po4 0.04ppm, do I need to bump up my Po4 more?

Randy Holmes-Farley · Sep 22, 2020

I don't know if the iron helped the cyano, but all photosynthetic organisms use iron from the water (or foods, if they also eat solid foods) and if it was a limiting factor for the cyano, adding it may have helped them. I personally would not want to limit the tank iron levels as a way to limit cyano.