[Bk828]

I tried the blackout before and it did more harm than good. What finally worked for me is Accu-clear with extra filtration and water changes. Green water went away in just a few days.

 

[Bk828]

is this the product you mean?

yes that but mine was API

I added drops as directed on the bottle, added more floss in the filter and as hours passed water went clearer and clearer. Later that day (say 10hrs later) I did a 50% water change and replaced the filter floss. I didnt rinse and reuse since I wanted all the green algae spores out of my tank.
Did the same thing the following day or the day after and what do you know it cleared up well.

Whats your current filtration on your tank??
Did you disturb the gravel recently??
Do you have root tabs in your gravel??

Heres some photos of my tank 5 months ago
With green water:

After a 90% water change..Did nothing but make the water cloudy and then green again in the next few days..

And after accu-clear and water change and adding more filtration..

Not sure if it will work for everyone.. But heck it saved me from spending $$ on a uv sterilizer.

 

[Bk828]

Ted im 99% sure the cause of your green water was disturbance of the gravel. Thats actually how mine started.

By filter floss i mean the polyfiber

Also try and add more filtration to the tank. See if you can invest in perhaps a smaller canister filter. Maybe one of the eheim classic lines.

 

[Bk828]

a blackout won't do any damage to my plants and fish will it? And should I feed my fish during this time? would dosing with Excel help or does that only help certain types of algae?

blackout shouldnt harm your fish/plants. But I had a bad experience with a black out.. Since i did it a few days after i trimmed my plants. So all the new trimmings melted. Plus they were the most light demanding plants.
You can feed your fish. Just without lights ofcourse. And when you do the blackout throw some sheet over the tank so it gets no light at all, no room light, sunlight.

Dont think excel works in this case.