Green water problem

[Weirong]

I have been experiencing green water in my tank for the past few months. Initially, hair algae was abundant but I managed to solve the problem. Right now, there is minimum algae in the tank but the water is still green.

Mine is a 5ft and is 2.5ft deep. I have 416w of light (4x55w and 6x36w) but have reduced the amount by cutting off the 4x55w tubes. I have also reduced feeding.

Fuana includes 40 harlequin rasboras, 50 neon tetras, 2 balloon rams, 3 SAEs, 5 otocinclus, 5 green corys, 2 dwarf puffers and about 40 yamatos shrimps.

Tank temp is around 25 dgrees and is heavily planted with Vals, Java Moss, Blyxa Japonica, E.Tenellus, E.Quadricostatus, nanas and Java Ferns.

Filtration includes a Ehiem 2226 and a huge Jebo 610 filter. CO2 at 6 bubbles per second. I have stopped dosing liquid ferts since the outbreak of green water.

Plants and fuana are doing great but I can't seem to get rid of the green water. Please help!

[vinz]

How green? If the plants are doing fine, it means they are still getting some light... i.e. green water not very "opaque".

Do a 50% water change and then a complete blackout. ie. tape cardboard or thick layers of newspaper over the glass, making sure no light gets in. Off the tank lights. No ferts! Stop CO2, put in an aerator (oxygen for fish/plants). Cover the top of the tank as well. Don't feed.

3 Days later, open up, do another 50% water change. Redose your fertilisers good and well. Including NO3 and PO4. Tank lights and CO2 back on.

Your plants may look a little worse for the wear but they will recover. You may loose a few sensitive ones, but otherwise the green water algae should be dead dead dead.

[Weirong]

Green as in really green. But why do I need to cover the top of the tank?
Will try your method and see if it works. Thanks.

[vinz]

Cover the top to minimise ALL light. For the top, you can just throw a clothe or towel over... maybe folded once. It can still breathe, and will drape over, covering most holes. The light case will hold it up and a few clothes pin will keep it from dropping in the water.

[Weirong]

Think my Tiger Lotus is really going to suffer this time.