Lighting Schedule

[SlimmSnake]

Greetings,
I have a question about scheduling lighting intensities in the tank. I have been noticing cyanobacteria (green slime carpet looks like algae but isn't) growing in two of my smaller QT tanks, and in this case I am pretty sure a major factor is too much light. These tanks just have inexpensive LED lights on top, on a timer, on at 7:30 am, off at 9:30 pm (the lights are not dimmable or variable, just on or off). I've read various posts about reducing light or having no light as part of the remedy, and long term, I was thinking about setting my timers to be off during the day while I am at work. So lights would be on from say 6:am to 8:am while I am home before work, and then off during the day (wouldn't be completely dark, some ambient light from windows) then on again in the evening from say 6:pm to 10:pm. Would this be disruptive to the fish at all? Would it mess up their circadian rhythms or anything, or cause them added stress in any way?

My main display tank (100 gal) rarely gets algae, but occasionally I find a small amount of this cyanobacteria growing on the very top of plants and driftwood that are very close to the light also. This tank has awesome AI Hydra lights that are totally customizable; so similarly I could program these lights to dim down during the day and brighten when I'm home.

Do you foresee any problems if I have brighter light mornings and evenings and dimmer light during the day?
Thanks!

[modealings]

Hey do you have a picture of this stuff? I've had it I'm my planted tanks but it usually stays on gravel and driftwood. I usually just tear down my tanks and sanitize. It's tough stuff (one of the oldest living organisms, right?) and id be surprised if it responded to a change in light schedule. Maybe you could try sanitizing your qt tanks and then using a dropper to spray h2o2 on the few spots in the planted tank?

[Filip]

There would be nothing wrong for discus fish if you divide the photo period on two .Just don't expect to feed them immediately after the lights goes on again in PM.

As for cyanobacteria, i also think this siesta light period or lower lights won't hurt them at all .They are not exactly an typical alge but bacteria and they are very resistant.
Good thing is that its soft and you can easily remove them manually during every WC.

[gordo33]

Last year I switched to LED LIGHTING on my 40 gal angel fish tank and 75 gal discus tank bother planted. 6 months later the angle fish tank developed cyanobacteria. Initially I tried increase WC and manual removal but it continued to grow back. After researching I found an imbalance between high out put lights and CO2 , and poor water flow contribute to this out break. Other reef and tropical fish Web sites recommended Seachem excel, which adds CO2 to the water column, decreasing the time lights are on and increasing water circulation. The seachem excel is dosed at double recommended rate for 10 days. Doing all of the above my tank has been free of the cyanobacteria for 4 months.

[SlimmSnake]

Yeah, I've been reading various posts about treating the cyanobacteria with Boyd's Chemiclean or API's Erythromycin, and increasing the water flow / eliminating non-flowing pockets of water, so I will work on things like that also. My question was just about whether a "not normal" day-night lighting routine would be disruptive to the fish, or cause them stress.

Here's a picture... this is a 10 gallon QT tank that is empty at the moment.93513
I manually cleaned the green stuff about 3 days ago, with w/c. It grows back fast in here, though.
93514
Here's another pic of a patch growing just on the sand.

My 20G QT tank currently has a few fish in it, so I clean it every day or every other day, so nothing really to photograph there, but each time I find small patches of cyanobacteria trying to grow on the sand or rocks.

Anyway, if the fish won't care, I think I will be adjusting the timers to turn the lights off for the majority of the day when I'm gone at work.

[rickztahone]

Fish could care less about the light. You can go without one, or you can leave it on all the time. I've seen it done both ways.