What is this?

Does cyanobacteria grow fast? yesterday i pulled out as much as i could, syphoned it, cleaned the glass and did a water change... And today at least half of the algae i pulled and syphoned out is back today. I also scrubbed the front glass yesterday untill it was clean and today the glass is green and hard to see through
 
It does grow fast. I've battled cyanobacteria for the last six months or so. Siphoning and pulling it out will slow its growth but it will recover fairly quickly. I have found that increasing water flow in the tank helps because it only seems to grow in areas where the substrate and plants are relatively undisturbed by water flow. I tried medication and it killed it off for a month or so but eventually it began to reappear.
 
I had tons of water flow (too much really) and I tried buying a lot more plants to help and I cleaned and cleaned and cleaned...that stuff ( cyano ) was going to be the death of my tank (as my husband wanted it out of the house cuz it smelled so bad) I had to get the antibiotics or else no more tank for me. If yours does not smell it might not be cyano. It sure does look like it though. It grows back faster than anything I have ever seen. It also breaks up into itty bitty bits that just seem to melt back into sheets again in no time. I did not try a blackout though because I didn't want to kill my plants that I had just bought. Once I did get rid of it though I have never seen it again. I do suggest figuring out what is causing it though...can you see where it started? In my tank it started right where a little sunlight was hitting the tank through my blinds....I fixed that fast. I will say though that using the antibiotics did nothing bad to my tank. I sure was scared though through it all...but in the end it was worth it.
 
It doesnt smell at all when you walk into the room you can smell the tank. I also can pinch the algae and pull it out in clumps it doesnt really break up too much. I put it up to my nose and you can barely smell anything at all, it just smells like a plant.. I am planning on going to the fish store when i have enough money to buy antibiotics or whatever i need to buy..
 
it's cyanobacteria. Antibiotics will treat it but do nothing to eliminate the undering cause which is excess nutrients. Add more fast growing plants and/or a phosphate remover. Don't bother with nitrate removers (other than lots of water changes) because cyanobacteria can fix nitrogen from the air. Also dimming the lights is another recommendation but that rarely works because cyanobacteria can grow in dim light while your plants can't.
 
AquariaCentral.com