Can photoperiod (time illuminating a tank) make up for lower light intensity?

[gjcarew]

I have a 36" Chihiros WRGB 1 that is about three years old at this point. It was an absolute powerhouse on a 22 gallon long, but now on my 75 gallon the light seems to be pretty low intensity. The rotala in the middle, for example, is supposed to be Rotala H'ra, and it barely gets orange. Buying a new light is currently out of my budget. Do you think I could get better color out of my plants by doing a longer photoperiod? I'm currently at 8 hours and looking at 11-12 hours.

One reason I ask is that I just saw that Cheattha Sae-Teaw (I almost certainly butchered that) is using a 48" Chihiros WRGB 1 on a 60" tank and getting pretty spectacular reds. His photoperiod is 11 hours. I believe Christel Kasselmann also runs 11-12 hour photoperiods.

Would I just be spinning my wheels? Is it worth a try? I'd love to hear any input.
Edit: Just looked up his name, and I did butcher it

 

[Freshflora]

I don’t know if it’s directly proportional, but it’s worth a shot as long as you monitor for algae IMO. Only downside beside possibly algae is using more CO2, so why not go for it? I believe generally you can also tease better colors out of Rotalas/lythracae with ammonia at the root zone, but it would have to be in a root tab with some type of soil mix to bind it since you’re using an inert substrate.

 

[Art]

Hi - so this is a complex topic. I will try to convey what I've learned and read.

There is an inverse relationship between intensity (PAR) and photoperiod. There is a growing body of knowledge on this point but in my layman's terms:

Every plant has a specific day light integral (DLI) - the amount of light it needs over a 24 hour period to photosynthesize optimally. I presume this means that the plant reaches photosynthesis saturation for enough time that it makes enough food to grow optimally. Think of it like a bucket that needs to be filled to the brim.

The amount of light hitting the leaf surface is what we call PAR in the hobby. I think of it like rain drops. Par is how hard it's raining (i.e., the amount of light drops hitting a certain section of the leaf concurrently). These drops fall into the bucket and start to fill it up.

So intensity (PAR level) that is high causes the plant to hit its DLI quicker than low intensity (low PAR) would. Therefore, the photoperiod doesn't have to be long to reach DLI or, in my analogy, to fill the plant's bucket. Alternatively, in a low PAR environment, a longer photoperiod (period of rain) will allow the plant to reach DLI. In other words, it will take longer to fill the bucket but it will get filled, nonetheless. It will simply take longer. Either way, you are meeting the plant's DLI.

I hope that came across as I intended it.

My recommendation is to slowly increase the photoperiod and see how the plants react to it. Please let us know what you find.

 

[gjcarew]

I don’t know if it’s directly proportional, but it’s worth a shot as long as you monitor for algae IMO. Only downside beside possibly algae is using more CO2, so why not go for it? I believe generally you can also tease better colors out of Rotalas/lythracae with ammonia at the root zone, but it would have to be in a root tab with some type of soil mix to bind it since you’re using an inert substrate.

I make my own root tabs with Osmocote Plus and mineralized topsoil. I've found that plants that get these tabs tend to be very healthy, but not as colorful. That may be because they are never nitrate limited.

There is an inverse relationship between intensity (PAR) and photoperiod. There is a growing body of knowledge on this point but in my layman's terms:

Every plant has a specific day light integral (DLI) - the amount of light it needs over a 24 hour period to photosynthesize optimally. I presume this means that the plant reaches photosynthesis saturation for enough time that it makes enough food to grow optimally. Think of it like a bucket that needs to be filled to the brim.

The amount of light hitting the leaf surface is what we call PAR in the hobby. I think of it like rain drops. Par is how hard it's raining (i.e., the amount of light drops hitting a certain section of the leaf concurrently). These drops fall into the bucket and start to fill it up.

So intensity (PAR level) that is high causes the plant to hit its DLI quicker than low intensity (low PAR) would. Therefore, the photoperiod doesn't have to be long to reach DLI or, in my analogy, to fill the plant's bucket. Alternatively, in a low PAR environment, a longer photoperiod (period of rain) will allow the plant to reach DLI. In other words, it will take longer to fill the bucket but it will get filled, nonetheless. It will simply take longer. Either way, you are meeting the plant's DLI.

I hope that came across as I intended it.

My recommendation is to slowly increase the photoperiod and see how the plants react to it. Please let us know what you find.

Thanks Art. My understanding is that red coloration is a response to light stress on a plant, but I don't really know whether that stress is due to light intensity or a general response to any illumination beyond the DLI. I'll keep y'all posted on the results.

 

[Art]

Oh sorry. I misread what you were asking.

In my opinion, a plant has a natural, optimal state of coloration. As you know, some plants have carotenoids or anthocyanins that result in an orange or red appearance. The important point is that each plant has a natural state, some are redder than others.

How to achieve optimal redness is what we should be asking. My thought is that we need to provide the plant with what it needs to grow optimally. That means, light, CO2 and nutrition. This doesn’t necessarily mean more of each. This is why lowering nitrate will turn some plants redder. They prefer a lower nitrate level.

I remember a visit from Claus Christensen of Tropica to Florida Aquatic Nursery. He was stunned at the Rotala macranda growing in shallow sunlit pools. He said that Tropica couldn’t get them to grow that big and red. It was obvious that FAN was doing something right and the plants showed it. The point, as Claus put it, the plant it growing optimally.

Bringing it to what you said, I think you need to dial in the lighting first and then pair that with the CO2 and nutrients. This should start to get the plants growing to their natural state.

Increased light intensity doesn’t translate to redder growth in and of itself. Plants do respond to too much UV, like we do, but this response has nothing to do with why these plants are redder in other aquariums.

 

[Pepere]

Instead of getting a more expensive replacement light…

perhaps a less expensive additional light to supplement what you have…

75 has a fair amount of depth front to back. Perhaps having the Chihiros all the way back and a cheaper light just in front off it to add more par..

George Farmer has this on his big tank. Each light on its own separate timer…. He keeps higher light plants where they can get the most, and lower light plants to the margins…