Lighting Times?

[Bobtastic]

Hi all,

Following a visit to TGM and being gift'd (thanks Jim!) a copy of the ADA Catalogue '09 I have a question about lighting times. In the catalogue it mentions that you should setup a concentration of light at noon, this being the time to put on your MH's. Do plants actually know when "noon" is? It suggests that plants have a biological rhythm so to time your lights to match this rhythm. I currently have my lights come on at 5pm and then go off at 10pm, this is more to do with the times that I am home then anything else. But this doesn't lead to the above theory... Am I not maximising the growth rates of my plants because of the lighting times?

 

[GreenNeedle]

You can take many things that ADA (or any other manufacturer) says with a pinch of salt.

As long as your tank is not in direct sunlight then you can set your photoperiod when you want. You in theory control when 'noon' is.

From the way the statement has been phrased (in your post above) I would have read it as a concentration of light at noon meaning a 'noon burst' at the users 'theoretical' noon. However where you say that it means when to turn the MH on contradicts my reading of the former statement.

Many people do have noon bursts but there is no evidence to say that a noon burst is beneficial. I would suggest that using say 100 PAR for the whole of the photoperiod would be the same as using 50 PAR with a 200PAR noon burst. Same amount of light through the photoperiod but seperated up.

There are differing reasons why a noon burst is used. Some because they feel it is more like nature, some because they think it is beneficial but the 'real' reason is normally because they have too much light to have it on all the way through and therefore limit the 'highlight' to a smaller section of the photoperiod.

So does it matter when the lights are on? If your tank is on a windowsill then yes. You will be getting sunlight at normal hours. If you then have a photoperiod later or earlier than the daylight then you are effectively running a much longer photoperiod and then of course stand a higher chance of algae.

If your tank (as mine is) is sheltered or shaded from direct sunlight you can see into it but probably only as much light as if you have moonlights are actually going in there. I have moonlights on all the time the main lights are off and I can see a slight glow (not as much as at night time) even now at 10am

So your answer is No you set the rules. you determine when 'daylight' is. Plants adapt to this as they do to different levels of CO2/nutrient/light colouration.

If it were the case that plants did indeed have 'biological timers' as some people try to suggest then there would be no point 'hydropnics' setups using 16 hours of light to speed up the growth of their 'product'. It would also mean that spring plants would appear in the same wek every year and not (as we all know they do) when the temperature and conditions meet their criteria. Daffodils/crocuses come out earlier in mild years and later in cold years.

In our setups it would also mean that we would not be able to run short photoperiods (4-5 hours) without seeing plant problems. We would all need to be running 12 hours

AC

 

[Bobtastic]

Thanks for the reply AC!

The MH comment would only apply to lighting rigs that have both MH and T5s in. Where u'd use the T5's through the photo period and then do the "noon boost" to simulate "noon".

I get extremely confused by all the lighting levels. I keep getting told that lighting levels are not that important, but I can see that certain plants have high light demands.... Will my 2x49w T's be enough to grow the likes of HC (if the ferts and Co2 levels are right?).

 

[GreenNeedle]

I get extremely confused by all the lighting levels. I keep getting told that lighting levels are not that important, but I can see that certain plants have high light demands.... Will my 2x49w T's be enough to grow the likes of HC (if the ferts and Co2 levels are right?).

Well I am one of those who says it ain't the light

Think of all the old problems with P and there being a false correlation. What I would suggest is yes when you up the light certain plants tart to thrive however, Consider your statement above.

(if the ferts and Co2 levels are right?)

Yes you boosted the light. So it is the light right? Why is it light and not CO2? When you boosted the lights you also upped the CO2 to match?

So if you boost the CO2 (or improve its delivery) would you see the same improvement in those plants? A test on 7 ADA disaply tanks suggests it isn't the light. Full HC lawns with low level PAR. ADA MHs have been tested as delivering way below the PAR expected. Excuse the pun 'A trick of the light'. lol Seems they please the guys who want highlight and ADA products by using some means to reduce the amount of light being received.

So Your T's? 2 x the full length of the tank. High CO2 well distributed.....You have HC lawns

Link to the ADA tests. These lights are delivering a third of light in comparison to non ADA MHs of the same wattage :
http://www.barrreport.com/showthread.ph ... ht+PAR+AFA

More light = Faster growth? Yes of course but not that these plants require the highlight. All plants grow faster with highlight but I would suggest that the term 'highlight plant' is one of those that should now be consigned to the 'myth bin'/

This is one reason why the Koralias have become so popular. Super distribution of CO2. People haven't reswapped out that extra light for the circulation yet though Boys and their Toys etc. I can't really talk about that subject as I have my 1.1WPG of LED up higher tan most MH users at the moment (11" above water level and 24" above substrate.) Maybe should reduce to 0.5WPG. lol

AC

 

[George Farmer]

I think the midday burst can be attributed to good results, especially when using a solenoid linked to lights, as the CO2 levels at the point when the burst has started is higher i.e. after 3 or so hours from the beginning of the photoperiod.

Once the intense light has given good growth and consequent CO2 consumption from plants, the lower lighting levels after the burst are more appropriate.

It's one effective way of maintaining compact growth through high lighting with less risk of algae, perhaps.

 

[Bobtastic]

I guess the "right" ferts and Co2 levels is a bit subjective... Obviously if they were right for the light things would grow... I suppose my roundabout question was, can higher levels of ferts (through EI) and Co2 make up of lower lighting levels (in comparison to higher high-light setups).

I do have concerns that the lights I have (2x49w T5's) dont have the "power" to penetrate the water column which roughly 60cm...

George - Are you saying that the Co2 be linked to the "burst" or that additional Co2 be added to compliment the burst? I thought the current thinking is that Co2 comes on 1-2hrs prior to the lights?

 

[GreenNeedle]

I guess the "right" ferts and Co2 levels is a bit subjective... Obviously if they were right for the light things would grow... I suppose my roundabout question was, can higher levels of ferts (through EI) and Co2 make up of lower lighting levels (in comparison to higher high-light setups).

Nope you will still be aiming for the same ppm no matter what the light. Just the plants uptake more and therefore you add more CO2 and nutrient are increased to hit the same target.

What I am saying is that with highlight, you add more CO2 and ferts. In many cases the 'deadspots' become apparent and are dealt wth, then things are back on track with faster growth. However I would suggest that if the 'deadspots' are dealt with before the lights then these 'highlight' plants would receive more (in quantity or consistency) CO2 in the first place and then they would be seen as 'high CO2' plants and not 'highlight' plants.

In essence get the circulation sorted at the beginning and keep monitoring it, adjusting positioning if necessary and you maintain a more consistent level of CO2 throughout the tank getting more to the subtrate level as well.

We already know that just adding CO2 means you are basically increasing light without touching the actual lights. Once the plants get abundant CO2 then they don't have to use energy trying to glean what they can and start to use their energy on ultilising the light better effectively 'upgrading' your lights by improving the CO2 levels. A CO2 tank can use much lower light at the lowest end than a non CO2 tank due to this.

I do have concerns that the lights I have (2x49w T5's) dont have the "power" to penetrate the water column which roughly 60cm..

Your lights should be OK if they are the length of the tank.

AC