# Some questions about light in the eventuality of CO2 not leading to much growth development



## amateurfishkeeper (6 Jul 2015)

I've been trying to understand what's going on with my plant development since introducing pressurised CO2. My assessment of its effect since using it is that it's been slightly worse than before using it. Obviously, I blame myself first for this rather than blaming CO2 because I'm obviously doing something wrong.

I've tried to tick every possible box.

1) Using EI dosing through the Aquarium Plant Food website's materials and method (Is this wrong?)
2) Flow throughout the tank (every plant sways, substrate looks clean)
3) A strict lighting / CO2 schedule through the day (10 hours light, 10 hours CO2 coming on two hours before lights on and off two hours before lights off (have tweaked this as well)
4) Daily Ph drop from 7.1/2 to 6.6/5 - don't want more CO2 going in because of the deleterious effect it had on stock before. Have a consistent lime green drop checker colour.

There could be something wrong in all that of course and if any sharp-eyed person can see something that's obviously wrong or worth experimenting with, I'd appreciate an idea.

Since most of the key things people talk about seem in place, my focus has been on lighting as the possible issue worth playing with. What I'd like to know is the following:

1) Is less lighting sometimes the solution rather than more ? Not all plants are the same and on the Aqua Essentials website I see that a lot of the plants I have have light requirements in the lower range. Could I have been giving the plants too much light? Is less light sometimes the solution rather than more light?

2) If the tank is in a room with curtains should I be keeping them drawn during the day so that no natural sunlight reaches the tank (it's not directly lit) or is natural light something that needs to be part of the mix?

3) Is ten hours of light too much or too little? Would it be better to experiment with reducing this or increasing it?

With thanks!


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## 5678 (6 Jul 2015)

Similar issues for me. I too am not seeing the speedy growth that I would expect for my setup. 

FWIW, I am going with the approach of lower light as that is the only thing I am not sure on. I have just dropped to 6.5 hours @ 45% on my TMC Mini 500. With a higher intensity I was seeing algae and also plants struggling with pale new growth. 
I'm now dosing EI and have lime green dc for my lighting period. I'm going to run at this level for a week and see how it goes. 

With your setup, light does sound a little high from what I understand, perhaps there is more light than the ferts/co2 can support? Might be an idea to reduce it and see how they respond?


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## amateurfishkeeper (6 Jul 2015)

Interesting. I'm going to try something similar I think.

I added an Interpet LED strip to my tank but found that the only place it would go is the front of the hood with the result that only the front gets most of the light. However, most of the background plants seem to prefer lower light conditions. I think I'll try this lower lighting level over the same ten-hour period and if that doesn't do anything I'll change to a shorter light period with higher intensity. Trial and error really!


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## 5678 (6 Jul 2015)

Sounds sensible. Drop to a lower intensity first and see how that goes.


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## Jose (6 Jul 2015)

amateurfishkeeper said:


> 1) Is less lighting sometimes the solution rather than more ? Not all plants are the same and on the Aqua Essentials website I see that a lot of the plants I have have light requirements in the lower range. Could I have been giving the plants too much light? Is less light sometimes the solution rather than more light?



It depends what bad effects your experiencing on the plants. Normally less is better than more.



amateurfishkeeper said:


> 2) If the tank is in a room with curtains should I be keeping them drawn during the day so that no natural sunlight reaches the tank (it's not directly lit) or is natural light something that needs to be part of the mix?


No natural sunlight, its not good generally when co2 is off.



amateurfishkeeper said:


> 3) Is ten hours of light too much or too little? Would it be better to experiment with reducing this or increasing it?


If plants arent growing better with co2 then its not the lights. Light is independent if you havent changed it.

I think you have probably one of the following problems.
1) You arent dosing enough of one or more nutrients which is limitting plant growth. Try dosing 2xEI and make sure you are dosing everything including Magnesium. Sometimes there are precipitation issues specially in hard water.
2) You might not be adding enough co2, or maybe you dont have enough flow in the tank etc.


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## amateurfishkeeper (8 Jul 2015)

Thanks Jose for the tips and ideas

I'm pretty sure it's not the flow - in fact, I've probably got flow overkill in the tank. 

But I have a question about what you said. When you say 2XEI do you mean 25ml of the mix X 2 per day or do you mean double the concentration of the EI mix in the dose and keep it at 25ml? I'll probably embarrass myself by them meaning the same thing but I'm just curious about what that means.


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## Jose (8 Jul 2015)

amateurfishkeeper said:


> But I have a question about what you said. When you say 2XEI do you mean 25ml of the mix X 2 per day or do you mean double the concentration of the EI mix in the dose and keep it at 25ml? I'll probably embarrass myself by them meaning the same thing but I'm just curious about what that means.



Yeap nothing to be embarrassed, Ive made a fool of myself in here quite a few times now but thats the good thing about the internet...
Dont over think it. Just Dose double. If you are dosing 25 ml then dose 50 mls now. If you dont see improvement just go back to the previous dose. But a huge percentage of the times its down to co2. Try to do a pH profile on your tank through the day to see the actual co2 levels. The idea is to get a  1 ph drop during the photoperiod.


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## Christos Ioannou (8 Jul 2015)

> The idea is to get a  1 ph drop during the photoperiod.


Before photoperiod starts.

Sent from my A0001 using Tapatalk


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## Jose (8 Jul 2015)

Christos Ioannou said:


> Before photoperiod starts.


Yes and keep keep it there during photoperiod. Thanks Christos i can see how I didnt explain myself.


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## MedicMan (8 Jul 2015)

Just a note... The ei recipie on APF is very weak . so unless you're dosing 20ml per 50l you may not see the growth you want. Check the correct concentration and record using wet's nutrient calculator


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## 5678 (8 Jul 2015)

MedicMan said:


> Just a note... The ei recipie on APF is very weak . so unless you're dosing 20ml per 50l you may not see the growth you want. Check the correct concentration and record using wet's nutrient calculator



Really? I've just started using that recipe and dosing 10ml per 50l. Are we saying 20ml per 50l is more on target?


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## Marcel G (8 Jul 2015)

amateurfishkeeper said:


> I've been trying to understand what's going on with my plant development since introducing pressurised CO2. My assessment of its effect since using it is that it's been slightly worse than before using it.


First, I would check the parameters of your source (tap?) water. Sometimes people use EI dosing although they have high nutrient levels in their tap water. This can lead to some problems.

Although my attitude to CO2 levels is not popular here, I think that if you have CO2 levels at 10-15 ppm, you should experience great results with your plants. In other words, there's no need to use more CO2 to have good and lush growth.

As to the EI dosing, in general plants grow best at much, much higher nutrient levels then we ever dare to supply them. I would say that the optimum level of nutrients for most aquatic plants would be somewhere around 100 ppm NO3 (some of which should be in the form of NH4), 50 ppm K, 10 ppm PO4, 1 ppm Fe. [Although I should add, that in real-world the exact optimum concentration is plant specific = different for different plant species.] This amount of nutrients is usually used in hydroponics for growing plants under optimal conditions without substrate. The problem is that we can't use these levels in tanks where there are any critters, as most fish and shrimps may not survive in such a "polluted" environment.

The last thing I would like to mention, is light. In our tanks, we can hardly supply our plants with too much light. In natural environment, aquatic plants are lit by 1500-2000 µmol.m-2.s-1 at water surface level. In our tanks they may have 300-500 µmol at most (and only a few people use 150 µmol PAR at the bottom).

So contrary to popular belief of EI people, I think the only thing our plants have in abundance in our tanks is CO2. As to the light and nutrients, we severely limit them by these two factors. But here lies another possible problem for us: algae. The stronger the light and the more nutrients, the higher the risk of algae in our tanks. So in all this we need to seek a balance => on the one hand we need to supply plants with enough light and nutrients (incl. CO2), but on the other hand we need to protect our fish (keep it in clear, unpolluted water) and keep a rein on algae.

So you can definitely try to use higher nutrient levels or higher light levels to increase plants' growth rates, but you need to be aware of possible results: bad environment for your fish + good environment for algae.


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## 5678 (8 Jul 2015)

Thanks Ardjuna... 

When trying to reach that balance, what approach would you suggest? 
I have (what I believe to be) sufficient CO2, and good circulation, yet do not see impressive plant growth. I am trying to increase the available nutrients first before increasing light levels. Does this sound sensible?


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## Jose (8 Jul 2015)

ardjuna said:


> First, I would check the parameters of your source (tap?) water. Sometimes people use EI dosing although they have high nutrient levels in their tap water. This can lead to some problems.


What problems?. If you have high nutrients already and you add a bit more what problems will you have compared to your normal tap water? None. Unless if you have very sensitive shrimp but then the problem is not dosing EI but your tap water to begin with.



ardjuna said:


> Although my attitude to CO2 levels is not popular here, I think that if you have CO2 levels at 10-15 ppm, you should experience great results with your plants. In other words, there's no need to use more CO2 to have good and lush growth.


This is not what most people have witnessed. Do you say you can get very good growth at 10-15 ppm of co2 even at high light? Well then you musht be the only one.



ardjuna said:


> As to the EI dosing, in general plants grow best at much, much higher nutrient levels then we ever dare to supply them. I would say that the optimum level of nutrients for most aquatic plants would be somewhere around 100 ppm NO3 (some of which should be in the form of NH4), 50 ppm K, 10 ppm PO4, 1 ppm Fe. [Although I should add, that in real-world the exact optimum concentration is plant specific = different for different plant species.] This amount of nutrients is usually used in hydroponics for growing plants under optimal conditions without substrate. The problem is that we can't use these levels in tanks where there are any critters, as most fish and shrimps may not survive in such a "polluted" environment.


I agree generally with this statement.



ardjuna said:


> The last thing I would like to mention, is light. In our tanks, we can hardly supply our plants with too much light. In natural environment, aquatic plants are lit by 1500-2000 µmol.m-2.s-1 at water surface level. In our tanks they may have 300-500 µmol at most (and only a few people use 150 µmol PAR at the bottom).


Whats the point of supplying more than enough light if you will get algae? The idea is to keep a nice looking planted tank, so for that you need nice looking plants and no algae. How do you achieve this? With crazy high light and 10 ppms of co2? No! it doesnt work.




ardjuna said:


> So you can definitely try to use higher nutrient levels or higher light levels to increase plants' growth rates, but you need to be aware of possible results: bad environment for your fish + good environment for algae.


So you are recommending to use more light with low co2 even though chances of getting algae are higher. How is this any better than trying to limit our plants growth via light whilst maintaining good levels of co2(e.g 30 ppm)?


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## Marcel G (8 Jul 2015)

Jose, I don't want to get into this endless debate again. We discussed this all some time ago. I don't need to convice anyone of it. If you don't believe it, let it be.
To explain a few things which you ask:
1) If tap water contains a lot of nutrients, and you add another handful of nutrients using EI, you create an environment which will favour algae. Whether these algae grow like mad or not will depend on other factors (that's another story).
2) In nature most aquatic plants have about 1 ppm CO2 available in equilibrium state + 1500 µmol PAR at the surface (in summer). In some areas (smaller streams) the CO2 concentration may be higher (around 10 ppm), which lead to a lush growth and lush vegetation. In such streams the water is supersaturated with CO2. Again, whether the algae will occur in there depends on other factors also. So I don't know if I am really the only one who uses 10-15 ppm CO2 + 150 µmol PAR at the substrate with lush growth and lush vegetation in my tank ... but in nature this is quite common (i.e. 10 ppm CO2 [+ sufficient amount of other nutrients] + 1500 µmol PAR = lush plant growth).
3) Read carefully: I do not recommend to use super high light with super high nutrient levels in our tanks. I just say that you can definitely try to use it ... if you want to find out what happens. What I recommend (on the contrary) is to seek a balance between nutrient level, light level and other factors which may play a role in our tanks.

PS: I know a professor who studies bladderworts for a very long time (decades?). These plants are not able to use bicarbonates, so they are strictly CO2 users. According to him, these aquatic plants are well able to experience very good growth rates under 10 ppm CO2 in greenhouses (with 1500-2000 µmol PAR). Of course their optimum may be around 40 ppm CO2, but as he told me there is no significant difference between the growth rate under 10 vs. 40 ppm CO2. Their Km (= half-saturation point) is 0.2 to 0.3 mM CO2 (9-13 ppm). I don't know how to explain it to you any better. I already tried my best without any success. So I give up. If you don't believe it, then don't read my posts. I don't know what else to say.


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## Jose (8 Jul 2015)

I understand what you say about nature Ardjuna and also what this professor says. But this doesnt mean its the best practice to keep a healthy nice looking tank with no algae. Also most of the plants we keep in a high tech aren't really aquatic and in nature they have access to the atmosphere. Everything you tend to suggest is based on the premise that we have to emulate nature all the time.

It sounds to me like you are just misreading the co2 levels in your tank.
There is also the variable of the misting. CO2 might not read as high but it might still make it to your plants in the form of microbubbles. I never see  you speak about these.


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## Marcel G (8 Jul 2015)

There might be a big difference between _*what plants need*_ for a good growth, and _*what is the best practice*_ with regard to keeping algae at check. I hope you understand this difference. According to what I know, what I have learned, and what is my experience in my own tanks, most aquarium plants grow well even under relatively low CO2 levels (10-15 ppm) ... although in nature these levels are extra high, and represent a supersaturated water (rich in CO2).
As to the plants we grow, I don't understand your saying that they are not aquatic. Maybe you wanted to say that they are amphibious, i.e. they are able to grow _*submersed *_as well as _*emersed*_. But once you put the emersed plant underwater, and the plant creates submersed leaves with a very thin cuticle, it can be considered trully "aquatic" (underwater or submersed). Plants with submersed leaves have usually the same "properties" as plants that are able to live exclusively underwater (like _Ceratophyllum _or _Vallisneria_) => i.e. you would hardly find out any difference in cuticle thickness. Of course there are differences between different plant species, but plant with submersed leaves can be considered a truly aquatic plant. So plants with submersed leaves have no access to atmospheric CO2. When you put the submersed leaf out of water, it will quickly wither and die. For the leaves to survive out of (above) water they have to become emersed (= have a thick cuticle with stomata)! So in no way am I suggesting to imitate nature in our tanks. In fact, we are far from the conditions which are common in nature. What I'm saying all the time is that our plants can grow well even under 10-15 ppm CO2. That, however, does not mean that the environment with higher amount of CO2 may not be better for their growth or for the inhibition of algae. In fact, I think that higher CO2 levels may be better in regard to indirect inhibition of algae, as higher levels of CO2 means lower pH, and pH under 6.5 seems to be hostile for some algae species. So again, what I repeat all the time, is that a great number of aquatic (submersed) plants should grow very well under 10-15 ppm CO2 because this level of CO2 should be nearly saturating for them. I did not do any serious experiments yet, but according to what I have read and learned, you won't get any substantial difference in growth between 10 ppm vs. 30 ppm CO2.
If you don't believe me, read what others say:
PEDERSEN, Ole; CHRISTENSEN, Claus; ANDERSEN, Troels. _CO2, Light, and Growth of Aquatic Plants._ Planted Aquaria, Spring 2001.
Look at the results of their experiment with Riccia:



 
Do you see any substantial difference in the biomass gain between 7 ppm vs. 35 ppm in Riccia?
Do you think the scientists did misread their CO2 levels?
I can publish much more examples, but the point will be the same. There is no need to publish more data when you persistently ignore them.
Sorry, I don't want to be harsh. But neither I want to discuss this matter with you any more.


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## MedicMan (8 Jul 2015)

5678 said:


> Really? I've just started using that recipe and dosing 10ml per 50l. Are we saying 20ml per 50l is more on target?


Aaanyway back on topic  

Yeah I believe APF says in plant heavy tanks (as I'm sure most of ours are) you should aim for a double dose. I would still calculate stuff from : 

yanc.rotalabutterfly.com


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## 5678 (9 Jul 2015)

MedicMan said:


> Aaanyway back on topic
> 
> Yeah I believe APF says in plant heavy tanks (as I'm sure most of ours are) you should aim for a double dose. I would still calculate stuff from :
> 
> yanc.rotalabutterfly.com



Thanks! 

I've switched to 20ml per 50l as of yesterday. I've also started adding a half dose of liquid carbon, moved my drop checker to where plants are struggling (limnophila hippuridoides) and have added a small Hydor pico to help with flow in that area. 
I also had a few of them uprooted by fish so have replanted them at the front of the tank to see how they cope there.

Will check that site for a recipe.


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## Christos Ioannou (9 Jul 2015)

After reading @ardjuna and @MedicMan I started double dosing Macro ferts. I did not change anything else.
Here are the effects on Vesicularia ferriei 'Weeping' moss and Microsorum pteropus 'Trident'. Similar throughout the tank...

Weeping moss is tight to a large piece of driftwood.
Trident on a rather smaller one.


I need to sink back both driftwood pieces daily, twice...
Little helped deputing @ 00:20


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## flygja (10 Jul 2015)

Christos, that looks like mega pearling action. What about before double-dosing?


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## Victor (11 Jul 2015)

MedicMan said:


> Aaanyway back on topic
> 
> Yeah I believe APF says in plant heavy tanks (as I'm sure most of ours are) you should aim for a double dose. I would still calculate stuff from :
> 
> yanc.rotalabutterfly.com


Hi, MedicMan. I'm not getting acess to this calculator. It is updated? Thank you.


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