# CO2, light & algae, my understanding.



## Danny (7 Feb 2018)

So before I start let me just say I am not an experienced user of co2 and am also new to a co2 enriched planted tank, my thoughts are based on my own understanding from hours of reading and a lot of trial and error and will probably confuse the hell out of you with my dodgy explanation lol.

This is a very poor description of my thoughts but hopefully it will make sense to some and even help some too.

Algae, everyones favourite thing.... Co2, the miracle cure.... Light, the evil of all tanks.....

My now limited understanding is that when co2 is used correctly to match the light being provided it should help reduce algae, co2 and light not matched correctly will cause algae yes.....well that is the way I look at it.

What happens when you are certain you are correctly diffusing and distributing the co2 to adequately match the lighting source yet algae strikes and hard.... a lot of confusion and searching for answers on how to fix it in my case.

My first step was to look into the circulation of the tank and co2 supply amount, the circulation I am positive was fine but I upped the co2. Then the lighting, that I decided was too intense and both shortened and reduced the intensity so I had my second answer to a lot of questions and was on my way to recovery right?..... nope

Time to look at the nutrients and dosing, using a nutrient rich substrate and dosing liquid ferts and lco2 I was sure I was providing enough of everything to supply the demand of the plants for them to be healthy enough to fight off algae but just incase I increased the ferts and lco2. That should do the trick.....nope

Going round and round in circles and not getting anywhere is not great, no matter what I tried I could not get on top of any algae. But why? I was doing everything by the book? The co2 comes on 2hrs before the lights and is as high as it can be without gassing the fish so whats the problem? why is everything going so wrong?

Time to reduce the dosing, perhaps that is the problem.... well from everything I understand you simply can't have to much ferts but its worth a try.... did it work... nope.

So I have got the lighting sorted, co2 sorted, ferts well they don't matter if they are too high so forget them as no difference to anything at recommended or 4x the dose.

What is left to try and put right? I have done it all? 

PH profile needed perhaps? Well I know the co2 is at the limit for the tank without killing the fish so no matter what I can't increase it and you can't have too much for plants anyway so no point as the only thing I could do is decrease it. 

Circulation and diffusion have to be fine, everything is growing great in all corners of the tank and its like a mini whirl pool in there.

Then comes the point when everything has failed just give up trying and see what happens, well everything just kept getting worse. If it is getting worse without me doing anything then it can't be something I am actually doing.....It has to be something I haven't considered. But what.....

For weeks I sat looking at the tank before the lights came on at 3pm and always observed the plants "reaching" for natural light, stupidly and blindly I did not pay any attention or thought to it and just looked on like a blind goldfish.

The tank is in a very bright room and does at one point in the morning get natural light directly on a small part of it, as you can see in the natural light the tank is not dark in the slightest on a bright day but the lights are off as is the co2.




For what ever reason I totally neglected the thought of the natural light and need for co2, the tank is awake clearly but it is still hours until the tank light and co2 come on.

So lets go back to the co2+light coupling, if they are matched correctly and the co2 is correctly diffused and circulated there should not be any real algae problems......

The most common question for people starting out with co2, "when do I turn my co2 on" one of my own questions too.

The answer "2hrs before the tank lights come on", the answer I followed.

Lets take a look at the tank again, the lights are off but the tank is awake...... the co2 is not due on for hours..... why? because of the 2hr rule.

Going back to the algae issues now, if co2 is correctly matched to lighting things like hair algae should not be a problem based on lighting and co2..... Anyone had a lightbulb moment yet? I did.

I live in a busy family home, have kids that go to school and so on. The house "wakes up" at 6:30am, lights on etc etc, on nice bright mornings the curtains are opened and even on not so bright as I am sure is the same for the majority of people.

Between the ambient light and natural light the tank also "wakes up" at anywhere from 8am ish, the fish and shrimp come out and the plants start to open. 

The tank lights are on a timer as is the co2, lights at 3pm and co2 at 1pm, they run until 10pm and 9pm respectively. 

With the tank "waking up" at lets say 8am and co2 not coming on until 1pm there is that precious gap in co2 of 5hrs in my case, in that 5hrs the damage to algae I assume is huge and the root cause of my problems.

If I had taken on bored what I had seen of the plants reaching towards natural light weeks ago I highly doubt I would have had the problems with algae I have, to sum up my rambling.

I am now matching my co2 to the house/natural light, it comes on at 7am and not the previous 1pm and not matching it to the tank light. 

It is still early days to say if it will make any difference but in my mind I am certain it will, with a tank in a room bright enough for the plants to start photosynthesis without the tank light on then when the light comes on it is just like a direct hit from the sun basically.


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## ceg4048 (7 Feb 2018)

Danny said:


> PH profile needed perhaps?


Yes, you need to do this and we need to know the KH of the water so we can tailor the expected pH delta if necessary.
Natural light hitting the tank will not matter if CO2 is implemented correctly.

Cheers,


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## Danny (7 Feb 2018)

ceg4048 said:


> Yes, you need to do this and we need to know the KH of the water so we can tailor the expected pH delta if necessary.
> Natural light hitting the tank will not matter if CO2 is implemented correctly.
> 
> Cheers,


I think I have sort or cross posted with this and my other post, please see this thread for my theory https://www.ukaps.org/forum/threads/co2-2hr-rule-myth.52066/page-2#post-512329


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## ceg4048 (7 Feb 2018)

Danny said:


> I think I have sort or cross posted with this and my other post, please see this thread for my theory https://www.ukaps.org/forum/threads/co2-2hr-rule-myth.52066/page-2#post-512329


Danny,
           We need to see your pH profile. Whatever assumptions you made were incorrect. Proper analysis requires proper data. Measure the pH at 30 minute intervals starting from gas on to lights off and report the measurements.

Cheers,


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## Danny (7 Feb 2018)

ceg4048 said:


> Danny,
> We need to see your pH profile. Whatever assumptions you made were incorrect. Proper analysis requires proper data. Measure the pH at 30 minute intervals starting from gas on to lights off and report the measurements.
> 
> Cheers,


I'll need to do a new one as I have re scaped since my last one, from what I remember based on the ph table I had over 100ppm which obviously isn't right but someone said the co2/ph profile was based on RO not tank water.


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## foxfish (7 Feb 2018)

I do see where you are coming from mate, although you have to realise that most tanks do have some natural sun light & that does not normally effect most peoples. tanks in the way you describe.
In the UK summer we get 18 hours of sunlight, my tanks look beautiful in diffused sun light but I don't need to switch my gas on 7 hours before my main lights.
I would be more tempted to reposition the tank or reduce the ambient light (net curtain perhaps) & stick to the required time for your C02 to give 30ppm.


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## Danny (7 Feb 2018)

foxfish said:


> I do see where you are coming from mate, although you have to realise that most tanks do have some natural sun light & that does not normally effect most peoples. tanks in the way you describe.
> In the UK summer we get 18 hours of sunlight, my tanks look beautiful in diffused sun light but I don't need to switch my gas on 7 hours before my main lights.
> I would be more tempted to reposition the tank or reduce the ambient light (net curtain perhaps) & stick to the required time for your C02 to give 30ppm.


I guess I'm just throwing the rule book out the window with my theory, I have no idea how much co2 I have in ppm I just know it's as high as the fish can take. 

I've simply broken down the basics of that if a plant has enough light to wake up it should have co2, given the basic understanding that light is not actually important but that co2 is surely if a plant has enough light for photosynthesis then co2 should be made available.

If I lived in a cave and the plants only woke up when I turned the lights on then fine but I and most don't,it is a tricky one to explain as I have nothing scientific behind it just the basic principle that plants are awake so feed them. 

If for instance photosynthesis mainly takes part in the first few hours of a plant waking up then surely by not feeding it for say 6hrs is missing the most vital part.

Think of a natural light South facing tank, it ramps up slowly to then full on sunlight, I'm now thinking the natural/ambient light is the ramp up and the tank light on is the direct sunlight.


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## Danny (7 Feb 2018)

I've also thought that even basing co2 on 30ppm is only actually because livestock won't tolerate much more than that, we have far more than 30ppm in the atmosphere where plants thrive so it's a bit of a misconception that 30ppm is needed for the plants rather than it just being a maximum level livestock will tolerate.


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## ceg4048 (8 Feb 2018)

Danny said:


> I'll need to do a new one as I have re scaped since my last one, from what I remember based on the pH table I had over 100ppm which obviously isn't right but someone said the co2/ph profile was based on RO not tank water.


I don't understand why this is an issue. We don't care about what the charts says. The chart is virtually always wrong at face value.
We care about the difference in pH from gas on to lights on. That has nothing to do with the chart for our purposes.
I think you have taken a left turn off the main road somewhere.
Please measure as best you can and provide the data.

Cheers,


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## Danny (8 Feb 2018)

ceg4048 said:


> I don't understand why this is an issue. We don't care about what the charts says. The chart is virtually always wrong at face value.
> We care about the difference in pH from gas on to lights on. That has nothing to do with the chart for our purposes.
> I think you have taken a left turn off the main road somewhere.
> Please measure as best you can and provide the data.
> ...


No offence Clove but I've not taken a wrong turn anywhere nor do I need to do a ph profile at this point, I do fully appreciate your experience and input but what I'm aiming to correct is my co2/light period nothing to do with lack of co2 during the lighting period, rather that infact the natural/ambient light should be factored into the lighting period thus co2 timed to correlate to it as opposed to the tank light unit  itself.


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## ian_m (9 Feb 2018)

Why don't you just put you CO2 on 24/7 @ 30ppm then you will have no worries about insufficient CO2 or need to understand lighting periods or continue this discussion as CO2 will always be availble. Much like EI for CO2. Done. You are happy, we are happy.


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## Danny (9 Feb 2018)

ian_m said:


> Why don't you just put you CO2 on 24/7 @ 30ppm then you will have no worries about insufficient CO2 or need to understand lighting periods or continue this discussion as CO2 will always be availble. Much like EI for CO2. Done. You are happy, we are happy.


We all know plants do not use co2 while they are "asleep" yes? So running 24/7 is just a waste, I really don't understand how me saying that factoring in this big ball of fire in the sky as a light source rather than only accounting for the light unit on the tank is so dismissed..... 



The basic principle of the 2hr rule is to have co2 at 30ppm for when the light comes on, I'm saying that in my case and others the light coming on does not refer to the tank light unit but the natural/ambient light source.


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