I was using digital timer and had a same problem. I switched to pins timer and works fine. I also think that is timer problem.

I agree, get rid of the digital timer, mine messed up and I put a mechanical timer bar on, problem solved.

Nono guys sorry my post might have been confusing,

Let me try again,

1.Timer goes on,
2.Light still off.
3.5 hrs later ............ Light goes on
4.Timer turns off
5.Light turns off.

Strange eh? Light was working perfectly fine before and it's NOT the timer, I have another light on the same timer and that ones fine.

And I do have a mechanical timer not digital.

have you tested the light in a wall outlet direct, and have it "NOT" go on?

The marineland fixtures are quite simple on the inside, and should not turn on after a few hours, sounds like a loose connection in the switch or where it plugs in.

Also look around for another AC adapter, could possible be that then.

No I haven't :redface: hehe I'll try that later

Can I use any ac adapter?

just look on the AC adapter.

It'll tell you what the output is, find one as close as possible to that. Marineland lights usually have a tolerance of +/- 100mA

How long is your LED light?