Shorter light periods?

[waterwatereverywhere]

I read somewhere that if you have the lights on for 4-5 hours, then a couple of hours off, then another 4-5 hours, it won't harm the plants but will help cut back the algae growth. But a lfs told me that algae has a shorter photosynthetic period than plants, and so if I did that it would encourage the algae!!! Any idea which if either of these is right?

 

[carrcn]

According to my sole book on aquarium plants, a lighting cycle will hurt the algae and not the plants. I've been doing this for a couple of months and have seen some amazing results of it. Doesn't wipe it out completely, but it does help. Plants are very efficient at switching "on and off." It doesn't take long for them to start their photosynthesis cycle, so you're really not hurting them as long as they're getting their 10-12 hours of light. I had mine on for 12 hours straight and have since cut it back to 11 with a 3 hour "nap" in the middle of the day. My plants have not seemed to suffer because of it, and I've seen quite a large reduction in algae growth. Good luck.

 

[waterwatereverywhere]

Thanks! I'll give it a go and let you know how I get on

 

[Lateral Line]

Interupted light cycles are much harder on lower plants, algaes and so forth, then higher plants who's photosynthetic mechanism is more sophisticated. High plants "switch on" much faster then lower plants in very simplistic terms. If the conditions are marginal, interruption can really push the conditions against algae.

 

[Silly me]

I think you are all WRONG ( I think )

this is right ( I think

But a lfs told me that algae has a shorter photosynthetic period than plants

In a bigger "green house" big lights are used in a 15min off 30min on cycle for 24 hours a day

There for the light switch on for 30min and the plants start their photosynthesis cycle, the 15 min the light is off is to short for the plant to stop their photosynthesis cycle and will not even notice the light was off..

But this "discovery" was not made to cut down on algae but to save cost

Algae can start there photosynthetic period for a much shorter period, this exhaust most algae so much that they wount grow out of control

 

[endparenthesis]

I had a lot of blue-green algae and I haven't seen any of it at all since I started doing this. The brown algae still remains though... low light's fault I guess.

 

[Dubby]

Thats very interesting info........ how will this on-off cycle affect the life of the fluorescent lamps?

 

[carrcn]

I'll try to get the book at lunch today and quote it exactly. I wouldn't put my faith completely in LFS personnel, as we all know their info is not always the greatest or correct. If I go home for lunch, I'll grab it. If not, you'll have to wait until next week. But from my personal experience, it has cut back on the algae and my plants look fine still.

 

[mrV]

how will this on-off cycle affect the life of the fluorescent lamps?

Not so good Every off/on clicks shorter they lifetime, but it's still best/natural way to prevent algaes to grow. So, if you have algae problems, keep your tubes off 3-4 hours in the middle of day.

 

[waterwatereverywhere]

I've got a metal halide lamp actually, which I replace every 12 months anyway, but yes that is something to watch I agree.