Hi folks, I've had this problem for quite some time now, probably looking at a month and a half to two months, My water is pretty much lime green about 48 hours after a water change, it makes no odds how little or much water is changed, my water is clear after it but within two days its turning green again. At first I thought it was my live plants so I took them out it changed nothing, my internal filter ended up packing in so I replaced it with an enheim internal filter which solved nothing. I have tried more sunlight and leaving the lights off (I was adviced to try both from different sources) and neither of which made a difference, I took a last ditch effort at using an algae killer from my local fish shop and it had no effect, any ideas would be much appreciated!