Do you guys run the air stone like it recommends or just rely on the skimmer?

Just skimmer. If you have a heavy fish load with large fish that might be affected, an air stone can't hurt.

I struggled with Cyano almost constantly until I stopped using "regular" gfo. Are you using GFO?

But +1 to chemiclean. The stuff works wonders.

Yea running BRS Bulk GFO 24/7.

I haven't heard that before.

It's probably not a well accepted theory, but cyano bacteria has a disproportionately high demand for iron, and they've evolved family specific pathways to harvest it from the environment called siderophores that might be able to pick up the form of iron found in GFO. Research around shipwrecks and black reefs have recently shown a strong correlation between the grounding/sinking of iron based ships, and the rapid decline of surrounding reefs as simple algaes like cyano over-take corals. A recent paper linked it directly to the iron rusting out the hull.

There are also half cocked plans to dump enormous amounts of iron in the open ocean to encourage phytoplankton as a form of carbon sequestration. A great deal of the phytoplankton in the ocean is free living Cyanobacteria. Different genera than the kind on your sand bed, but the kinds we deal with have many of the same needs and capabilities.

Anyway it's clearly more complex, and there's more to cyano outbreaks than just iron, but I have anecdotally experienced drastic changes in its behavior just by starting or stopping the use of GFO. I use PO4x4 now, which isn't granulated, it's polymer encapsulated. Produces zero dust and theoretically releases less iron in to the water column. It's expensive as all get out, but I haven't had any issues with cyano since.

So I have been running the red slim remover for 48 hours now but there is still quite a bit left. Wondering if I should remove it now and try again next week or keep it going for a 3rd day?

It is working but slowly.

I'd leave it. I usually run it 3 or 4 days, then do my weekend water change

Just follow the instructions on the box. You may need to re-dose again next week or so.

Fwiw, your tank looks quite mature, how old is it? Your rocks also don't allow real good flow around them. I think it's time for a revamp. Cyanobacteria is VERY good at utilizing nutrients and can even bind nitrogen, so even a very small amount of nutrients in the system is enough for cyano to flourish. I have a feeling there is a fair bit of nutrients in your tank, but the cyano is utilizing it so it's not in the water for you to test.

Haha, good ole reefing advice - conflicting. ;)

Your right l should get a new bigger tank haha.

It's about 2 years old the rock is much older. If I increase the flow anymore it whips up the sand