Lights on for how long ?

[DiverDude]

Noob question here....

I have a 28 Gal setup I just got. Tank was established and I've moved it to my place. Everything seems fine and water is nice and clear. No fish yet; just LR a few snails and a hermit crab.

I have a horrible work schedule and I'm out of the house from ~8 am to 8 or 9pm. When I get up, I of course turn the LED moonlights off and turn the main lights on (50/50 PC light) and gaze upon my little slice of ocean. I then leave them on until I go to bed around 11pm. Was thinking about this last night and that's a LOT of daylight !!

I'm going to put it on a timer, I think, so that it limits it to about 10 hours or so (1pm - 11pm ?). This will mean I can't see it in the morning but....

How much light is too much ? Opinions ?

I'm considering building a canopy for this that will have 2x75W MH and some T5's. If I do this, would the INTENSITY of the light dictate a change in exposure time at all, or should I just be trying to mimic an average amount of 'day' ?

Thanks.

[FitoPharmer]

remember, corals come from equatorial regions. so they can have 12 hours of daylight. I would say your corals should be fine with your current PC's being on 12 hours or a few more 11am-11pm. defiantly get a timer, I find corals like a more regular light schedule then you could provide by hand. if you have bad viewing hours, get really good actinic LEDs and buy florescent corals, they look better at night/morning. Once you upgrade 12-14 hours might be too much for lower light corals if you keep them, or impact on algae growth.

[Parker]

There aren't any hard an fast rules about how long you should light your tank per day. Your tank and your preffered viewing habits will dictate what works best for you. There are some that say that corals can only uptake so much light per day and anything beyound that is a waste, I've see people throw out numbers of 5 - 8 hours per day. I would assume that this would change depending on the strenght of your lighting. I've never put much stock in these conversations as everyone and every tank is different, it will let you know what happening.

I have have 3ea 14k 400w D/E metal halides and I run my lighting from 4pm to 10 pm.

[FitoPharmer]

too much light depends on what your keeping and your tank. Too much light usually means too much heat, that will kill corals. But corals can also be killed from just too much light (bleaching by either intensity or duration) the symbiotic algae inside the coral can no longer take the conditions. If your corals are looking good, growing, and color is usually a good sign, your light is not too strong or on too long. Given enough time and the right conditions, it is crazy how much corals can adapt to light changes.

[George]

First of all, when you are cycling your tank, you don't need any light at all. After your tank cycled, you can turn run you PC lights for 10-12 hours a day. use a timer to turn on and off to match your schedule so you can enjoy your tank. As soon as you get your MH lights, you can turn on the MH lights for 6 hours a day.
I had an accident where my MH lights were on the whole night because of a stuck timer. My corals and fish didn't seem to be affected by it.

[Parker]

too much light depends on what your keeping and your tank. Too much light usually means too much heat, that will kill corals. But corals can also be killed from just too much light (bleaching by either intensity or duration) the symbiotic algae inside the coral can no longer take the conditions. If your corals are looking good, growing, and color is usually a good sign, your light is not too strong or on too long. Given enough time and the right conditions, it is crazy how much corals can adapt to light changes.


Very true, I was speaking more to the point that people are saying corals stop up taking light without negative affects, IE: 8 hours of light vs. 5 hours of light. The corals are not affected by being lit for 8 hours but after 5 they are no longer benefiting from it. This all assuming optimal conditions such the 8 hours of lighting isn't over heating the tank etc.

Again, I have no idea how much truth there is to the theory outside of the extremes, I was simply speaking to what I have read. It might be a pile of crap for all I know. :D

[BC564]

I run my lights for 6 hours a day....3pm - 9pm

[DiverDude]

ok...well I don't have any corals right now but I'm thinking of adding them in the future (hence the research on metal halides). Reading between the lines though, the general consensus is that ~15hrs a day my PC lighting is running now is not likely harming anything but it is probably wasteful.

OTOH, if I had MH, then 15hrs might, in fact, be bad.

[DiverDude]

Did more research and was having a lot of trouble finding 75W metal Halides (I have a centre brace in my 29 Gal tank and don't want a shadow from the brace so 2 lower wattage lights would be needed instead of a single lamp) and came across a section of the USHIO website that was quite informative:

http://www.ushio.com/products/petcare/aqualite.htm

In it, they state that MH lights should be on for at least 12 hrs a day...

No telling if that's a marketing ploy to use more lamps or if that's from a sound biological rational.