Lighting on for 12 hours?

Definitely not – unless you want some trouble in the form of algae. Once in a while I hear of hobbyists who leave their lighting on for this long and it always surprises me. I hasten to add, they’re normally the one’s with problems in their tank too.

Lighting duration should be approximately 8 hours per day with no siesta (these don’t work). So lets say 1pm to 9pm is a popular time to have the lights on for. If you are suffering from algae problems my first suggestion is to drop the lighting down to 6 hours per day. Similarly for start up tanks, keep your lighting limited to 6 hours as the plants are yet to root and therefore not much growing is happening.

12 hours of light is just excessive. Not only will it cost you more but your lights will need replacing more often and your electricity costs will be higher. Not only that but you will need to clean your tank more often, particularly the glass.

How long do you leave your lighting on for?

8 thoughts on “Lighting on for 12 hours?”

  1. Well this would explain my algae problems in the past. I switched my lights on at 8am and off again at 11pm – I think that makes me doubly excessive !!!!!!!

    Thanks for the advice

    1. Glad it was useful Paul 🙂

      You sure had your lighting on for a long time heh! Imagine the electric you will save now. Your tank should also start to improve as well so let me know if I can help anymore.

  2. Great question Rini 🙂

    Few do but if you can then the you really have to gauge how your plants are doing. I would say if you dimmed the lights by say 50% then running them for 12 hours would be the equivalent of a ‘normal’ 6 hour lighting period.

    Do you dimm your lights at the moment?

    1. Not yet, i’m waiting for my tank to be build. I already bought the ATI Sunpower Dimmable. So as soon as my tank is up and running I’ll start experimenting…!

  3. Very helpful!
    Started out with a planted tank and I did leave the lights on for 12 hours or more. Been a couple days and no fish yet so found this forum at the right time!
    Lights set to 6:00pm to 12:00am currently and CO² set from 4:00pm to 11:00pm.
    Any sugestions?

  4. This is a very useful article. I have always had my lights on for 12 hours in total (10 hrs full and 2hrs at half) to represent the daylight as it occurs in the tropics. However, I have recently been having issues with bba in my 50L tank. I have therefore cut the lighting down by 2 hours. I also suspect the outbreak has something to do with a combination of recently rescaping using sand and having hard water too.
    Cutting the light down is the first step in my attack on bba.
    Thanks Richard.

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