Who Gives A Fish Forums

I've got a live planted tank and my lights are on from 6:30 till 5. I was wondering if it's possible to turn them off for 4 hours during the day and add those 4 hours on at night. I'm at work from 6:45 till 5 so I don't get to see my tank much. Just asking, don't want to stress my fish or kill my plants.

I'm in a similar situation, work 7/8am till 6pm ish. I've got a timer setup, plugs into the mains, light into timer, and that runs from 1pm to 9pm daily. No issues so far. If your tank gets daylight, that's a different story though.

No daylight on the tank, I was thinking of 6-9 and 12-9 with the timer, do you think that'd be alright?

I've got my lights on a timer, 9 am to 9 pm, works for me.

Had you any issues with algae?

It's better to have the tank light period consistent, rather than breaking it up. Since you're not home from 5:30 am to 6 pm, it makes sense to have the light on when you're there to enjoy the aquarium. You can set the timer to turn the light on during the day, say 12 noon or 1:00 pm, and off at 8 pm or 9 pm, depending on your schedule.

There are a couple of things to consider. Firstly, the room shouldn't be in darkness when the tank lighting comes on or goes off. You want ambient room light, whether from a window during the day or artificial lighting at night, for at least half an hour before the tank lighting comes on and after it goes off. This helps avoid shocking the fish with sudden light/darkness, which isn't natural. You're aiming to create a sort of dawn and dusk, like in nature.

Secondly, there needs to be a period of continuous complete darkness during each 24 hours. This is when the fish's biological processes slow down, and they relax. It's similar to our sleep. So, in the example above, this would be from 9 or 10 pm, after the tank lighting and all ambient room lighting is off, until dawn when daylight may enter via a window.

The reason for this has to do with the circadian rhythm, a biological clock that runs on a 24-hour period. Fish, like all animals, have this rhythm, which is governed by light. Not only do their eyes perceive light, but their cells do too. This is why we experience jet lag, and there are problems when daylight savings time occurs. In fish, this light/dark response is even greater; every cell on their body reacts to light and dark.

Once you establish a regular tank lighting schedule, you'll notice that the fish will come to expect the light coming on and going off. That's because of their circadian rhythm. Experiments with blind fish have proven that this response doesn't depend on the fish's eyesight, but because every cell is affected by light and dark.

This is why the tank lighting period should always be continuous and roughly the same every day. It makes the fish's life simpler, as they can save energy for more important things, and there's less stress when everything occurs the same day after day. Some high-tech planted tank aquarists might suggest the siesta approach, but biologically, this is harmful to the fish. Plants can adjust to varying periods, but fish can't, at least if we want them to be in the best health.

If algae is a problem, reducing the tank lighting period is the best way to deal with it. Sometimes, an excess of fertilizers can cause algae too. But it's better to sort out the light/nutrient balance rather than jumping into something that will be stressful to the fish.

You had any problems with alge

You had any problems with alge

Thanks for the advice, I'll definitely give it a go. One thing that's got me wondering is, when I'm at work and the lights are off, will the fish still eat? Also, I stopped using fertilizers about 2-3 months ago and my tank's been doing great since then.

A dimmer effect is what we're after, but I thought that didn't exist in aquarium lighting - however it seems I was wrong. I came across the Dsuny Programmable Dimmable LED Aquarium Light, which seems to be exactly what I was saying we need, a gradual change in light to mimic nature.