Well, no one has asked, but what are your water parameters? Do you happen to have a phosphate testing kit? Algae cannot grow, and I can't stress this enough, cannot grow without nutrients. It's using something in your tank as a food source. Usually green water is a unicellular bloom and can be cleaned with a diatom filter. They are expensive, but someone once mentioned on here that shops will somtimes rent them. That would clean it up short term, but you still have to get to the root problem: excess nutrients in the water. It might just have been dead plant matter (you said the fish ate them, then said you pulled them out, so I assume there was some plant matter floating around for a bit?) Also, a total blackout will kill algae, and since you no longer have plants, I would say go for it. Here's how I would do it:
Do a 50% water change. Vacuum the sand. I use sand as a substrate too, the sand isn't the problem. You can hold a gravel vac over the sand at an angle and "skim" the sands' surface to pick up waste and such. You pulled the rocks, but I do not know why. If they have algae on them, clean them, then rinse in dechlorinated water and put them back in. Make sure there is no sunlight coming into that tank at any time. Now, here's what should help a bunch; fast the fish for a few days. Don't feed them anything for 4 days. After that, don't overcompensate and feed them a bunch thinking they must be hungry. Feed them normally after that. During the fasting period, cover the tank so no light gets in. After two days, do another 50% water change. At the end of the four days, do another water change. This period of fasting and no light should clear it up.
Always remember, algae needs two things to live: light and food. I would also suggest you re-examine your feeding habits. If the fish use all of the food you feed them, the algae could never grow. Fish are opportunistic feeders. They will eat whenever you feed them. Have you ever noticed as well, that when you feed your fish, they poop? Mine do this. So as something goes in, something else moves out and makes room for it. Sometimes fish waste has undigested food in it. That could very well be feeding your algae. I never feed my fish more than they can consume in one minute. This way, they use what they eat. Also, I do not know what your maintenance shcedule was like before, but aim for 50% water changes once per week. This keeps the bad stuff down at lower levels. HTH.
) could be the cause of the green?