Midday Burst

[SuperColey1]

I run my lights 3hrs @ 0.9WPG, 4 hours @ 1.8WPG, 3 hours @ 0.9WPG.

I have done this for quite a while (different lights and timings) to sort of replicate nature a little.

Then I stumbled on a comment by a respected poster on another forum stating on a thread about midday bursts, that they were useless as the plants can only adjust to one level, that being the higher level. This would mean that the plants would only use the 4 hours leaving the rest for the algae to use as they adapt quicker.

He suggested that if the poster was intent on keeping a routine where there is subdued lighting either end of the main photoperiod to make it 1 hour or less and increase the main burst.

If I were to adapt this on my setup it would mean I would then have 1,8,1 (hours)

What are your thoughts on the above statements. Does anyone disagree?

Interesting

Andy

 

[Dave Spencer]

Strangely enough, I have added a midday burst on my 120l to reduce the lighting. I do 3 hours 1.7WPG, 3hours 3.4WPG and 3 hours 1.7WPG.

I get pearling during the first 1.7WPG, increased pearling during the 3.4WPG and decreased pearling during the final 1.7WPG. It is surprising how quickly the pearling reduces during the switch from 3.4WPG to 1.7WPG.

If the lights come on at the lower level, I don`t see why the plants can`t respond to this. The fact that mine all pearl suggests to me that they are responding to the lower light.

The other thing that strikes me is, if the poster says that the plants are only responding to the higher light levels, why suggest the one hour subdued lighting at the beginning and end, if the plants can`t adjust.

Dave.

 

[Liam]

In my tank in garden the sun hit the tank at 2.00 for an hour and a half. The plants would show no pearls before the direct sun but within half an hour of the sun they would pearl like crazy. I thought it might be a temperature rise causing the water to saturate more quickly but the temp in the tank didn’t rise so it was the light alone. On overcast days the plants didn’t pearl at all. So it seems to me that plants can respond very quickly to an increase in light.
So I disagree with the respected poster.

 

[George Farmer]

Well I have no scientific proof that it works better.

I know a lot of high light users run this method with success though, including Amano, Senske, most of the CAU etc.

It seems logical that only having a short high light burst is helpful to minimise algae, whilst still providing demanding plants with sufficient light.

Whether or not the poster is 100% correct? I don't know for sure. But the midday burst works well for many. Period.

 

[DevUK]

The other thing that strikes me is, if the poster says that the plants are only responding to the higher light levels, why suggest the one hour subdued lighting at the beginning and end, if the plants can`t adjust.

Dave.

Not sure why they suggested it, but I do it so as to ease my fish into the day without blasting them suddenly with lots of light I find my fish seem to prefer it. Not so sure about the plants though, as I don't really get pearling anyway (well not much)

 

[Underwurlde]

Why am I sat here thinking that for the last hundred-thousand-billion-trillion years that plants have cunningly elvoled to use sunlight, which strangley enough is not connected to an on / off switch. The closer things in our artificial tanks match nature the better IMO.

Andy

 

[nry]

Very true - not as if the sun suddenly comes on, shines, then goes off for the night! Plants will get a gradual build up of light intensity throughout the day as the sun rises and passes overhead....though maybe if the Earth was flat.....hmm....

 

[garuf]

If only Tom Barr answered he'd know the answer for sure.
I Personally disagree with the person who said it doesn't work, plants in nature grow in all light intensitys which fluctuate through out the day surely they can use all of the light they receive regardless of its intensity so it shouldnt matter if theres a change in light because the plants will still be able to use the light.

 

[plantbrain]

Well ,many folks do not have the option for a noonday burst.

I personally have aversion to aesthetic tank designs with big old bulky hoods and lots of lights.
Too big, too complex, too many wires etc.

Light is easy to manipulate though and it's the main thing that drives CO2 demand/uptake and there by nutrient demand/uptake and ultimately growth.

Some brands in the EU have dimmable FL lights, which are cool.
Not so in the USA.

I think the question is why a burst vs all day, as most plants do get exposed all day in the tropics, eg the Pantanal etc for 10 hard hours at least.

Well, it's reduce light energy, which reduces the CO2 demand, the nutrient demand and slows the growth.
I think it's just a trade off vs higher light all day.

Less growth, less CO2 demand, less electric cost etc.
All of which make things easier to maintain.

So does low light in general.
But some like to add a bit of high light just for a bit.

At 1.5 w/gal, CO2 and nutrient demand is low and pretty flexible(most any method works pretty good here).
At 4w/gal, things are required at much higher rates.
But if you only do it for 2-3 hours, then there's not as much demand vs 10 hours.

Now you can measure the same system with/without 10 hours vs 3 hour blast and measure the differences in Nutrients and CO2 as well as O2. Go back andf forth a few times and you'll see that the rate of growth and nutrient demand is much less, why?

Simple. You are adding less light.
the only requirement is that you also have a low light system up for 8-10 hours as well.
That adds bulk and cost to the system.

But more options.

I approached this issue a different way. I use less light, but use high intensity MH's, but I move the MH's on a rail front to back of the tank.

This causes more angels of strike on the lower leaves and does not creat hot spots, effectively getting more efficacy out of the light, because 1), they can be placed lower now, 2), less wasted light over spray outside the open top tank, 3), better spread of the light, 4, still have relatively lower light and requires less cost.

For pictures, working on the tank etc, I simply raise the lights up.

Moving light, just like the sun.
Now that's more natural than noon day burst.

Regards,
Tom Barr

 

[nry]

So is there any truth in the comment that a high-light burst period keeps low level plants (e.g. HC) growing low when compared with running a single lower light period?

 

[SuperColey1]

I answer to Dave, the poster wasn't suggesting an hour at either end as usefule, more a case of if you must have your dawn/dusk then just have a short one.

I still do this method but as per the tropic pantanel part above (although didn't know the name) I thought the light in the tropicas was pretty constant all day and not so varied.

Still an interesting subject to ponder!!!

(I do still have mine on 3,4,3)

Andy