# Optimizing CO2 in non-injected tanks



## MichaelJ (12 May 2021)

Hello,
I am looking for ideas to optimize the CO2 levels in my non-injecting tanks.

In both my ~150L (40 US Gallon) tanks I am striving for the lush wild overgrown look - I have no algae to speak of and good plant health and growth overall - for a low-energy tank at least… I already trimmed down and cut back on the plant mass a bit  (and will probably do more) - I think this may be the most significant thing I can do anyway, but I am always curious to what people are recommending in addition.
I am going to increase surface agitation a bit  (without stressing the fish and frogbit) to get that slight extra bit of CO2 uptake. Maxing CO2 in Low Techs
Since I started the tanks about 10 months ago I’ve run them almost constantly at about 26-27C (79-81F) and thinking of gradually lowering temps to about 24-25C (76-77F). My understanding is that as water temperature goes down the CO2 uptake from the air and the bio-availability of CO2 goes up?  Lowering the temperature will also slow the plants metabolism causing slower growth and lessen the plants uptake of CO2 as well, so that all sounds like a win-win theory - albeit fairly marginal I assume?
My light levels have always been quite low - long hours (11) but low intensity and lots of remarkably thriving frogbit to provide additional coverage.  I am wary about changing my light setup as I have reached a very good compromise on that part, but I suppose cutting back an hour or so would somewhat increase the CO2 production from the plants themselves.

Other tweaks I can make?

Cheers,
Michael


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## PARAGUAY (14 May 2021)

If you have soft water you probably have decent background levels of CO2 Maybe w/changes regularly done keep the levels up? This could explain your plants doing really well. If not a % of rain water added. I have read 22 degress is a prefered temperature for most aquatic plants but depending what fish you keep of course. Adding liqiud "carbon like Easylife but that moves the tank up a little from lowtech. Someone more knowledgable may reply


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## MichaelJ (14 May 2021)

@PARAGUAY Thanks.  Yes, my water is somewhat soft I suppose (KH 5-6 / GH 5-6). I don't know how much that plays into the CO2... what I am trying to accomplish is somewhat of an equilibrium between plant mass and available CO2. By optimizing the CO2 usage (lower plant metabolism, trimming and cutting back etc.) and uptake from the air (lower temp, surface agitation) I was hoping to give my plants mass a bit more "buffer". Of course, there is no way around cutting and trimming back on a regular basis.


PARAGUAY said:


> Adding liqiud "carbon like Easylife but that moves the tank up a little from lowtech. Someone more knowledgable may reply


I am not quite sure about liquid carbon - I used Excel at some point long time ago, but stopped dosing it as my Vallisneria especially started to die. I know others have success with it - especially combined with CO2 injection.      

Cheers,
Michael


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## PARAGUAY (17 May 2021)

Your right liquid carbon affects some stems egeria as example but some of the can grow emmersed types are ok . Vallis seems particarly in not thriving with LC. Mosses were reportedly also not liking LC. Dennerle do Bio LC not sure about it. Think adding remineraliser and a couple of WC weekly will keep plants happy


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## MichaelJ (17 May 2021)

@PARAGUAY Thanks. Yep, my mosses also didn't cope with the LC... but the mosses was never doing great anyway.  I think I'll just keep it as it is for now with the changes I've made. I lowered the temp about 1 degrees C, increased surface agitation a bit with surface skimmers that also provide aeration and cut an hour off my light cycle. I am doing 40-50% WCs per week already with a DIY remineralizer and that seems to work fine.    

Cheers,
Michael


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## ScareCrow (17 May 2021)

I've switched to rain water and have been using a siesta period to try and make the most of available CO². I can't tell if it's made a difference significant difference because I also rescaped at the same time. I'd say there is some improvement in plant health but the main benefit is getting to view my tank in the morning and evening.


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## jaypeecee (17 May 2021)

MichaelJ said:


> My light levels have always been quite low - long hours (11) but low intensity...


Hi @MichaelJ

You may want to take a look at posts by @Christel. I think she prescribes what you have said above.

JPC


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## MichaelJ (17 May 2021)

jaypeecee said:


> Hi @MichaelJ
> 
> You may want to take a look at posts by @Christel. I think she prescribes what you have said above.
> 
> JPC


Hi @jaypeecee  Thanks! I will conduct a search through her posts.



ScareCrow said:


> I've switched to rain water and have been using a siesta period to try and make the most of available CO².


Hi @ScareCrow I would have to set up a container to see if collecting rain water is a feasible route in the spring/summer/fall months. We do get a lot of rain around here, but I do not know how suitable it is for aquarium usage - I would guess that it is - perhaps with some active carbon filtering to remove  potential toxins?

Cheers,
Michael


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## ScareCrow (17 May 2021)

MichaelJ said:


> I would guess that it is - perhaps with some active carbon filtering to remove potential toxins?


Personally I don't use active carbon but it might help to remove heavy metals and other non-organic pollutants. As a basic check I test the TDS before I use it. If it hasn't rained for a while, I divert the water from being harvested for a few hours, to reduce the chance of pollutants entering the storage barrel. There is a more sophisticated approach called first flush, which I'd like to setup one day.


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## Christel (1 Jun 2021)

Of course, you can use rainwater, of course, it must be filtered. The problem is that sometimes you do not have clean rainwater. If it stands too long, bacteria form - blue algae then come in the aquarium.  It is especially important to create a stable environment in your aquarium. Using different water again and again leads to unstable conditions. I tried this for a long time for ecological reasons. But then there was no rain for weeks.....


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## MichaelJ (1 Jun 2021)

Christel said:


> Of course, you can use rainwater, of course, it must be filtered. The problem is that sometimes you do not have clean rainwater. If it stands too long, bacteria form - blue algae then come in the aquarium.  It is especially important to create a stable environment in your aquarium. Using different water again and again leads to unstable conditions. I tried this for a long time for ecological reasons. But then there was no rain for weeks.....


Hi @Christel Yes, the inconsistency worries me as well. And of course, for me here in Minnesota it would only be feasible to collect 6-7 month out of the year because of the cold and storing the water indoor is not practical in my case. We do get a lot of rain here though.
Cheers,
Michael


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## zozo (2 Jun 2021)

Some people use vinegar in low-tech aquariums and report increased plant growth... I guess from a chemical view this is because any aquarium contains bases as well as acids... Adding an acid reacts with the bases and it releases CO².








						Acid-Base Reactions
					






					chem.libretexts.org
				



Now I'm far from a chemist thus for anybody more familiar with the theories. Please correct me if I'm wrong and there are other reasons why adding an acid could be beneficial for plant growth!?

In some old-school LFS's you still can find Oakleaf extract which is also a rather acidic solution. I know it was very popular in the past for adding humic substances and regulating Ph. It might still be used today.

Regarding the aquarium, I have no personal experience with regularly adding acid to the water. I don't like to play the chemist with my tank and rather leave it as is. All tho I know small amounts don't do harm and do use vinegar for cleaning the stains from the glass and some of it ends up in the water. Also no idea about the correct amount of dosages I guess as long as it is in a safe Ph range it's ok. But adding too often too much pH might crash below safe ranges. It's something to be cautious with.

But in theory, adding acid will boost CO² availability.


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## MichaelJ (2 Jun 2021)

zozo said:


> Some people use vinegar in low-tech aquariums and report increased plant growth... I guess from a chemical view this is because any aquarium contains bases as well as acids... Adding an acid reacts with the bases and it releases CO².
> 
> 
> 
> ...


Hi @zozo I suppose that might work for a small amount of co2 for a short amount of time. I am wary about adding too many chemicals to my tanks as well - especially not knowing the potential downsides. I used to be caught up in targeting a specific PH range in part because of misconceptions about CO2. Months ago I essentially decided to not 'care about PH' anymore and just go with whatever my 50/50 tap/RO mix WC water is (somewhere around 7.2-7.4).  Even if I could boost CO2 by adding some chemicals / acidic substance I suspect the effect would be very short lived. I much rather have a lower, but consistent and sustainable CO2 level that balances with the plant mass and uptake that the plants have adapted to, than the occasional boost or spikes you might get from adding chemicals.  I do have drift wood in my tanks, mainly for decor, but that also tend to acidify the water a bit.

Cheers,
Michael


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## zozo (3 Jun 2021)

Here is a podcast about the subject from somebody who did.








						Dosing Vinegar in Your Aquarium | ScapeFu046 - ScapeFu
					

Learn why dosing vinegar, a carbon source, may be beneficial to your freshwater planted aquarium. It even fights cyanobacteria.



					scapefu.com
				




 Another theory I once did try in practice but was a rather short-lived experiment because the equipment broke down.
Since I have a tank with a wet and dry trickle sump and the bacteria in the trickle media excrete CO². Thus I did put a lid over the trickle part and did put in a small DC12 volt air pump salvaged from an old coffee machine. And hooked a ceramic diffuser to the tubing.

In theory, the naturally produced CO² from the sump is pumped back into the tank. Now I have absolutely no clue how much CO² will be produced in there, but whatever comes out of it definitively is being reused, and is a slight optimization.

It took a few months for the old air pump to break down and I didn't like the noise that much.  So I didn't continue the experiment. I wasn't planning to continue with placing a VAC 220 volt air pump in a wet environment. Also can't say it made a difference... But it doesn't change the fact that bacteria in trickle sumps fart a small amount of CO² while doing their job. Then why not catch it and use it, if it doesn't help then it won't hurt either.


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## Tim Harrison (3 Jun 2021)

I think soil substrate is an invaluable source of carbon and nutrients. Good oxygenation is really important too, increasing decomposition of the organic matter in soil and the subsequent release of CO2.

Hard water has its advantages. Some plants can manufacture carbon from bicarbonates and thrive in hard water, vallis, Anubias, Crypts, Aponogetons, Echinodorus to name but a few.

Also you're okay to reduce the temp of the tank to 23 degrees. All my tanks have been kept at that temp.


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## zozo (3 Jun 2021)

Another one, but this ain't optimizing but actually injecting... An old-school trick from gardeners used to grow better plants was the use of gas burners. Such as gas-burning greenhouse heaters. It heats the greenhouse and the gas flame produces extra CO². And this is a proven concept that works for terrestrial plants.

I actually have noticed myself in the past when we still had a water heater in the bathroom with an atmospheric gas burner and a pilot flame taking the needed air from and also exhausting in the same room. Anyway one day I noticed that the plants in this bathroom did exceptionally better than the same plants outside this room. I asked my neighbor farmer about it and he told me, so I learned about the use and benefit of gas-driven greenhouse heaters. And what my old-school water heater with pilot flame actually was doing, was filling the bathroom with extra CO².

Nowadays due to safety regulations, those water heaters are no longer in production.

Bottom line, terrestrial plants in a small room with a constant burning small gas flame definitively have an advantage from the extra CO² from the flame. 

I always wondered what if you would have an aquarium in such a room with an air pump and an airstone?

What about a fireproof cabinet with a tiny gas burner and an air pump in it?


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## MichaelJ (3 Jun 2021)

Tim Harrison said:


> I think soil substrate is an invaluable source of carbon and nutrients. Good oxygenation is really important too, increasing decomposition of the organic matter in soil and the subsequent release of CO2.


Very true. Walstad points that out as well.  I try to keep a good circulation with no stale or dead areas around the tank and try not to stir up the substrate too much when I clean during my weekly WC.



Tim Harrison said:


> Hard water has its advantages. Some plants can manufacture carbon from bicarbonates and thrive in hard water, vallis, Anubias, Crypts, Aponogetons, Echinodorus to name but a few.


Agreed. Eventhough I keep mostly soft water fish, I do try to not go too soft (currently around GH 5-6) and my Crypts, Anubias (a couple are flowering now) and Swords are doing great. My Vallis are struggling a little bit, probably due to the soft water.


Tim Harrison said:


> Also you're okay to reduce the temp of the tank to 23 degrees. All my tanks have been kept at that temp.


I've seen that recommendation before. I think 23 C is too cold for my livestock (in particular the Rams and Cardinals). My current compromise is 25 C - some claims thats the lower end for Rams, but mine are doing fine it seems.




zozo said:


> What about a fireproof cabinet with a tiny gas burner and an air pump in it?


Now that's an idea that has "DANGEROUS FUN" written all over it    Not to mention the fury of my wife



zozo said:


> But it doesn't change the fact that bacteria in trickle sumps fart a small amount of CO² while doing their job. Then why not catch it and use it, if it doesn't help then it won't hurt either.


I like the alternative ideas, but I think I am just going to rely on what the substrate in the tank will do when organic matter decomposes.

Cheers,
Michael


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## Tim Harrison (3 Jun 2021)

MichaelJ said:


> I think 23 C is too cold for my livestock (in particular the Rams and Cardinals


For what it's worth, I've kept both at that temp, often together, and both species thrived. But you're the best judge of what works in your tank


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## MichaelJ (3 Jun 2021)

Tim Harrison said:


> But you're the best judge of what works in your tank


Not always, that's why I am asking experts such as yourself  Cardinals in their natural habitat So much for 23 C being too cold for cardinals... I always thought Cardinals would be better off in the higher 20 range... turns out to be more like mid 20


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## John q (3 Jun 2021)

MichaelJ said:


> My current compromise is 25 C - some claims thats the lower end for Rams, but mine are doing fine it seems.


 Rams are a bugger to keep at the best of times due to mass farming and inbreeding etc, I think if you've gotten decent stock then they may well tolerate slightly lower temps but I've personally never had any luck with them below 25⁰c. 


MichaelJ said:


> My Vallis are struggling a little bit, probably due to the soft water.


I have vallis in lowtech softwater tanks 2~3 kh and 3~4 gh and they grow like weeds. I add a few catappa leaves to lower the ph a bit, not sure if this helps them in any way.


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## MichaelJ (3 Jun 2021)

John q said:


> Rams are a bugger to keep at the best of times due to mass farming and inbreeding etc, I think if you've gotten decent stock then they may well tolerate slightly lower temps but I've personally never had any luck with them below 25⁰c.


@John q  Yes, I am _mostly_ concerned about the Rams. I think the stock I have are decent. I am hovering around 25 - 25.5 C right now. I might be able to squeeze the temp a tiny bit more - perhaps 24.5 C.  Of course the point of all this per my OP is to slow the plants metabolism a bit - lower the CO2 demand and slightly increase CO2 uptake from the air. I have no idea how much to expect - maybe a ppm of CO2 perhaps.



John q said:


> I have vallis in lowtech softwater tanks 2~3 kh and 3~4 gh and they grow like weeds. I add a few catappa leaves to lower the ph a bit, not sure if this helps them in any way.


The Vallis are not doing terrible, just not as well as they used to. Could be they liked the water that was a tad more acidic. They should have a fairly wide tolerance range though. I think they may bounce back eventually - I had that happen before.

Cheers,
Michael


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## MirandaB (3 Jun 2021)

zozo said:


> In some old-school LFS's you still can find Oakleaf extract which is also a rather acidic solution. I know it was very popular in the past for adding humic substances and regulating Ph. It might still be used today.


Amtra do an Oak extract but crazily you can't get it in the UK


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## sparkyweasel (3 Jun 2021)

zozo said:


> What about a fireproof cabinet with a tiny gas burner and an air pump in it?


From one of my dad's old books, _Tropical Aquariums, Plants and Fishes_ by A Lawrence Wells, 1937;


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## MichaelJ (3 Jun 2021)

@sparkyweasel  That is pretty hard core low tech and hilarious!  ... and you can tell swords were popular even back then even


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## zozo (3 Jun 2021)

sparkyweasel said:


> From one of my dad's old books, _Tropical Aquariums, Plants and Fishes_ by A Lawrence Wells, 1937;
> View attachment 170261View attachment 170262


I've also seen drawings like this with candles from victorian times. Where the bottom of the tank was described as from a thick piece of slate to withstand the heat. But that's a nice book you got there dating 1937...  Seems to be in excellent condition as well... Keep it like that, one day it might be worth something.

I guess back then they didn't really know the benefit of CO² in the planted aquarium or else there definitively would be an air pump in it as well with a gas flame. Since CH4 + 2O2 -> 2H2O + CO2


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## zozo (3 Jun 2021)

MirandaB said:


> Amtra do an Oak extract but crazily you can't get it in the UK



I only found it once a few years back as New Old Stock, but unbranded, in a very old LFS and I bought it. And I actually don't know why... I guess I was intrigued, but never really used it all. Still have that bottle standing somewhere with at least 1/3 of its contents. 

Edit:
Found it... This is bought about 8 years ago, never seen it again somewhere.

It says in English Oak Bark Extract.


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## John q (3 Jun 2021)

MichaelJ said:


> Of course the point of all this per my OP is to slow the plants metabolism a bit - lower the CO2 demand and slightly increase CO2 uptake from the air. I have no idea how much to expect - maybe a ppm of CO2 perhaps.


Probably very marginal gain by dropping the the temp by 0.5c, a much better gain would be gotten by reducing the light intensity; simple cheap and easy, but folks can't grasp it. 


MichaelJ said:


> Could be they liked the water that was a tad more acidic. They should have a fairly wide tolerance range though.


Maybe, maybe not. The oak leaf solution mentioned above lowers the ph, adds tannins and humic acids. Catappa leaves do a similar thing.. maybe it's the tannins that help?


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## MichaelJ (3 Jun 2021)

John q said:


> a much better gain would be gotten by reducing the light intensity; simple cheap and easy, but folks can't grasp it.


Absolutely agree.. low light intensity (not necessarily the hours in my experience) is the key for low tech tanks... and probably the one key reason my plants in both tanks are doing so well without injection. 

Cheers,
Michael


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## tiger15 (4 Jun 2021)

Since indoor air has higher CO2 than outdoor air, good surface agitation / aeration can enhance CO2 recharge from the atmosphere to replenish depleted CO2 from photosynthesis.  I am deducting this from monitoring the CO2 level in my zero tech shrimp bowl in which CO2 is stripped to 0.2 ppm at the peak of sunlight period.  If I could provide good aeration, it would restore CO2 to equilibrium level with the atmosphere of at least 3 ppm.


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## Tim Harrison (4 Jun 2021)

sparkyweasel said:


> From one of my dad's old books, _Tropical Aquariums, Plants and Fishes_ by A Lawrence Wells, 1937;
> View attachment 170261View attachment 170262



Amazing, I love old books like this, thanks for sharing. I had a very similar book I wrote about in the History of Aquascaping, where it recommended the use of a methylated spirits burner to heat an aquarium made out of an old biscuit tin.


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## JozefSC (4 Jun 2021)

Hello everyone

I am not worried about CO2, it is in the title non CO2 tank, you just have to go with the flow it slowly growing tank and it always will be, that's the beauty of it, low maintenance, plants stay nice for longer same size no need for constant trimming. Once the tank is established it is very stable environment with no hassles, no algae etc. The CO2 is there, it come from fish, plants at the night time and surface movement.
If you want bust your CO2 just do DIY CO2 that will bring the CO2 higher but not too much, it will be big difference to it, and don't worry about fluctuations of CO2 as long you periodically refill the bottle and don't increase you light and you have the right temperature.


I had low tech tanks for ever(mostly for breeding fish), in my low tech tank I don't use liquid CO2, low light up 8 hours, 23'C, tab water, quite small internal filter, lean fertilizing and gravel no soil, but I have been adding some tropica tablets recently, up to now I wasn't, just fish waste and I believe big part of success in this are snails red-rimmed melania they are helping with oxidation in the gravel for bacteria and movements in there and I don't siphon the gravel at all(I know sounds mad) I have plants rated medium such as Monte Carlo, rotala, super red mini and rotala wallichii rated advance, I am not saying that the plant are thriving in its best, but they are growing slowly and healthy, even my rotalas are getting bushy after trim 2-3 stems coming out of one stem. Anubias, buce are flowering regularly. I don't want to spam it here with my photos for visual "prove". There are some photos of the low tech tank on Instagram @jozef.sc but if you are interested I can put some here. It fully planted tank with no more space for plant so I guess the amount of plant mass is not the issue, I would say more the better. 


I have learn from old school guys to don't put crypts and vallesneria to the same tank as each plant is changing the environment to its own standards and one doesn't like the other, depends which plant is stronger in the tank, or if there is balance or big volume of water then can be doable. Please don't quote me on this one, I have never used both together, so non experience with it.

Regards
Joe


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## MichaelJ (4 Jun 2021)

JozefSC said:


> If you want bust your CO2 just do DIY CO2 that will bring the CO2 higher but not too much, it will be big difference to it, and don't worry about fluctuations of CO2 as long you periodically refill the bottle and don't increase you light and you have the right temperature.


Hi @JozefSC   I was thinking about that, but then again, if I go down that route I might just get a small CO2 system and inject low levels for a couple of hours before and after the lights come on. My goal is to keep it as is and work with whatever I can do to squeeze out that extra CO2... it seems like I might already be there with the addition of a slight tweak to temperature.



JozefSC said:


> I don't siphon the gravel at all(I know sounds mad)


I've backed away from being too rigorous with the gravel siphoning as well (gravel cleaning is detrimental according to D. Walstad - a bit extreme perhaps...). I just get rid of obvious plant waste and detritus.



JozefSC said:


> I have plants rated medium such as Monte Carlo, rotala, super red mini and rotala wallichii rated advance,


Impressive. I've tried Rotala W long ago (bought in ignorance not knowing its a "high CO2" plant) - faded away in a week.



JozefSC said:


> I am not saying that the plant are thriving in its best, but they are growing slowly and healthy, even my rotalas are getting bushy after trim 2-3 stems coming out of one stem. Anubias, buce are flowering regularly. I don't want to spam it here with my photos for visual "prove". There are some photos of the low tech tank on Instagram @jozef.sc but if you are interested I can put some here. It fully planted tank with no more space for plant so I guess the amount of plant mass is not the issue, I would say more the better.


Your tanks indeed looks great! - yes, please share 1-2 pics of your low-techs (as not everyone here is on instagram).

Cheers,
Michael


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## JozefSC (4 Jun 2021)

Well great is a bit too big word, it is my first planted tank and it will one year now since I started focusing on plant and scape.

Now I am hoping that my plant identification was correct as I brought the plant without label and emersed, Rotala W should be the one top right corner. 
Photo 7th April





8th May


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## MichaelJ (4 Jun 2021)

JozefSC said:


> Well great is a bit too big word, it is my first planted tank and it will one year now since I started focusing on plant and scape.


I like it... so much going on there in a good way! 



JozefSC said:


> Now I am hoping that my plant identification was correct as I brought the plant without label and emersed, Rotala W should be the one top right corner.
> Photo 7th April


Not sure if it is... the Rotala W I got looked like this - for a few days at least 

Cheers,
Michael


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## JozefSC (4 Jun 2021)

Yes, definitely not that colour, structure is same. I am sure someone here will know and tell us.


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## JozefSC (3 Sep 2021)

Hello, how is the tank? Did go CO2 or not?


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## MichaelJ (3 Sep 2021)

JozefSC said:


> Hello, how is the tank? Did go CO2 or not?


Both tanks are doing great. Besides what I mentioned in the OP, the only change I ended up doing with respect to "CO2 optimization" was lowering the temps to 24 C.  I never really considered going down the CO2 route - it's too much hassle for what I possibly could gain with the plants I keep. I believe I found a very good balance between fertilizer, light intensity, filtration/flow and plant mass - I just have to try and maintain that.
Cheers,
Michael


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## JozefSC (3 Sep 2021)

Great, balance it always the key good look.


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