For the siphoning though I can only siphon out the water when I do a water change right? I tried siphoning the water with algae into a bucket through a filter so only the water goes into the bucket and then put the water back into the tank, but problem is the water was disgustingly brown and looked really gross and I was scared to put it in the tank.Siphoning out when removing can be effective. Rich also mentions using a Marineland polishing filter in tank when cleaning to catch and remove debris that's floating in the water. I don't think high nutrients are the issue, if they are actually as low as you are testing. Plenty of tanks have algae issues with high and low nutrients, and plenty of tanks that have high or low nutrients don't have algae issues. It's simply ecology - there's nothing competing with the algae so it thrives.