Ok one last post before I go to bed. Just siphon the water and try to draw out as much of the red cyano
as you can. I would try to siphon out that much and then toss that water. Maybe five gallons. Then draw out how much you need to for to paint the back of the tank. I would make sure if you use spray paint to cover the top. I would suggest you roll the paint on. Except for the water you siphoned the cyano
out just re add to the tank. There are some that have suggested you pull the LR
out and scrub. If you do it needs to be with SW
. You`ll need to have plenty of SW
ready to replace all that you are throwing out.