In search of middle-earth - a quest for a middle energy tank

[Art]

Hey man, sorry for not posting much here, it has been a busy year.

@Dennis Wong we know you are building a successful business and producing a wonderful site for the hobby. You are welcome here whenever you can find the time. Thanks for all you do.

This thread has really taken on a life of its own and some wonderful topics discussed. Some that need further thought and study for sure. In reading some of your responses, I wish Diana Walstad was here to add to the conversation.

My hope with this thread was to provoke thought on finding a middle ground that give more buffer to aquarists in terms of husbandry but that also allowed for a greater variety of plants in the aquarium. That's where I'm aiming my tank after the reset. Let's see how successful I am.

At the moment, I tend to agree with @Krandall in that I think CO2 is the limiting factor in non-injected tanks. Anyone have a different view?

 

[Yugang]

With all due respect to my fellow and more knowledgeable hobbyists, I have stopped recommending no-CO2 tanks to beginners.

For historical reasons, I believe, we have made CO2 injection more complicated for beginners than necessary. True, for some of the top ranking tanks we want a lot of CO2, and want it to ramp up fast and then be very stable. But is this really a necessity for a beginner, and wouldn't it be better to settle on a good-is-good-enough advice to beginners so that they can start on the learning curve?

As an example a thread that is active right now on another forum, where the OP question is "How do you know the correct injection rate for Co2, is it possible to know before adding plants?". Here are some quotes from some of the most experienced and respected members in that thread:

• "I use a drop checker and setting CO2 injection rate just takes a few days."
• "Can take quite few days/weeks to get a stable pH, lots of fine tunning"

These people know what they are talking about, and their advice is indeed how we approach it in the hobby. But reading this, a beginner may think twice if he/she is committed to go into that rabbit hole.

We are not yet quite there, but I believe the advice for future first time users of CO2 would be:

1. From your tank surface area, you calculate the correct CO2 Spray Bar to give you 15 ppm CO2. The Spray Bar will cost you 5 USD.
2. Keep your CO2 on 24/7, so that you don't need to worry about ramp up/down or instabilities. CO2 consumption will be very low.
3. Drop checker is optional, not required, and you don't need any knowledge about KH or water chemistry for correct CO2 dosing.
4. Install your CO2 Spray Bar, inject enough for it to release a bubble a few times per hour in overflow mode, and you're all good. Don't worry about your regulator stability, as long as the Spray Bar overflows you are good enough.
5. Stop worrying about CO2, you will have a 15 ppm and perfect stability and can focus on other aspects of a successful tank.

It can be that simple. The hobbyists can later decide when it is time to start playing with controllers, reactors, ramp up/down or pushing the maximum CO2 without gassing the fish. This is a learning curve, and some may soon try, while some others are just forever good enough with a stable 15 ppm and no worries.

I step off my soapbox, thanks for reading

 

[Yugang]

I am now about 2 months into my experiment with 15 ppm CO2, and perhaps I post an update for comparison In search of middle-earth - a quest for a middle energy tank and after.

For the first period I kept CO2 on 24/7, as consumption was really low anyway and I wanted to eliminate any instabilities. Recently I have started to use timer/solenoid again, with CO2 on for 12 hours. Inspired by @sudiorca , I have not reduced my lighting, which still is about 100-120 PAR at substrate. Ferts is about 50% EI.

Intitially my plants almost stopped growing, clearly from a need to adapt to the change from >30 ppm to <15 ppm. Growth then picked up again, but I would estimate on average now 50% reduced compared to high CO2. I enjoy this, I can do my maintenance more detailed, and don't feel after 4 days that all the good work has been eliminated again by new growth.

I wanted to give this experiment some time, two months now, as my experience is that plants may have some reserves before crashing, or changing shape, so I wanted to be sure that I waited long enough and have the full picture.

I am posting this FTS, the tank clearly needs some pruning and scaping, as an illustration that I feel that my plants are still doing pretty well. I am starting to be a little impatient, and plan to push the limits further and see where that leads to.

 

[sudiorca]

I have not reduced my lighting, which still is about 100-120 PAR at substrate.

Here is a slide from my AGA talk which elucidates the importance of maintaining medium to high light in low CO2 environment (provided other important factors such as substrate quality, water parameters, temperature, good maintenance etc; have been taken care of).
Panel A shows effect of light intensity on wildtype (fully capable to activate RuBisCo upon illumination) and mutant (mostly unable to activate RuBisCo) Arabidopsis.
Panel B is in vitro experiment showing similar results as panel A but the activity is saturating around 100-120 PAR which is most likely caused by the excess supply of Mg and ATP (since it is an in vitro study with high available resources unlike Panel A which is an in vivo study and cells usually operate in non-saturating conditions).


As we can see from the above slide that RuBisCo activation in dependent on RuBisCO activase enzyme and this enzyme's activity is dependent on light intensity.
This is great but how medium to high light is beneficial in low CO2 environment? Let me try to explain in layman's terms:
I think it is really important for everyone to first understand that in order to successfully carboxylate Ribulose 1,5-bisphosphate or RuBP (substrate of RuBisCo which incorporates the other substrate, CO2), CO2 has to first come in contact with RuBisCo (collide with RuBisCo). Now, if CO2 collides with an "active" RuBisCo, carboxylation of RuBP will happen (photosynthesis) but if RuBisCo is not active then the collision will be futile.
Now, let's consider a low CO2 and low light tank. In this condition, there is less availability of CO2 as the name suggests which means the probability of collision with RuBisCO itself is low and then if the collision somehow happens, it is more likely to be a futile one as low light means fewer "active" RuBisCO.
This relationship flips in pressurized CO2 injected (hightech) tanks. In these type of tanks, there is plenty of CO2, so the probability of collision with RuBisCO is quite high. That's why these tanks do just fine even in relatively lower light intensity with fewer number of "active" RuBisCO as there is higher probability of collision with CO2.

Summary: Medium to high light intensity in low CO2 tanks ensure higher number of "active" RuBisCO which compensates for the low level of CO2 to some extent, so most collisions between RuBisCO and CO2 are going to be successful (provided other important factors have been taken care of as I have mentioned many times).

 

[Yugang]

Thank you so much for your insights @sudiorca . I had no idea that this is the good reason to keep relatively strong lighting, I was keeping light at 100 PAR under the less valid assumption or hope that I could try and avoid the plants reaching for light and for that grow less compact.

I am not sure how to take my tank further with discovery and probably failure at some point. I am hoping for what looks like a real high tech tank, as you succeed in doing, but with much much less CO2 injection. I can't try to replicate the conditions that you create, as I am not into dirt substrates, do not have 0 d KH nor do I have low temperature.

My tank is at about 2-3 dKH, depending on season, and with lowering CO2 injection I guess that at some time pH will increase to the level (like 7.3) where it starts to affect the CO2/bicarbonates ratio. By measuring with a drop checker however, I can target my measurement on dissolved CO2, whatever the total DIC is.
My tank water is typically 27 C right now, which again is not optimal and higher than your recommended setting.

After 2 months of testing I see very little compromise (at least with the plants I have) with 15 ppm injection, and am contemplating if I want to start using a 1 dKH drop checker and target for about 8 ppm "free" dissolved CO2 in the water with an even smaller CO2 Spray Bar in overflow mode. Will this push the limits too far, and will my tank look and grow like we expect from most low tech tanks, or could I mimic a true hight tech tank that just grows much slower?

 

[Marwen]

I used to define "energy" in high/medium/low energy tanks as light+CO2 levels.

I now define it as only CO2.

I've seen successful tanks with very strong light and low CO2. If the profile of available nutrients is complete (as in no deficient nutrient) and the tank is clean, plants will just adapt their growth rate and form to the available CO2.

I know first hand what high CO2 like 40+ ppm does with high PAR. My tank will measurably eat up tons of NO3 and PO4 when run in that mode. 15 ppm NO3 and 6 ppm PO4 will easily disappear to 0 ppm by the end of the week. Still kinda blows my mind. (For PO4 it ain't the soil, it's already saturated. I know because when I lower the CO2, NO3 and PO4 uptake drops measurably).

Trying leaner regimes under such conditions has lead me to issues. Mainly the plants start pulling macros from their older leaves = prematurely weakened leaves = algae on them. I don't know how some guys can have "high" CO2 and dose 1 ppm NO3 per day. I could never make that work. Either we have different definitions of high, or their soil is supercharged with nutrient supplementation (I haven't tried that yet so I can't tell), or their CO2 is lower than they think. As in believing having 30 or 40 ppm, but really having 20 ppm so more of a medium energy tank.

 

[Yugang]

I am now about 2 months into my experiment with 15 ppm CO2, and perhaps I post an update for comparison

As a reminder, against conventional wisdom I kept my light at full throttle, 100 Watt LED on a 50 gallon tank, about 100 PAR 10 hrs. As I did not want to change too many parameters, I kept dosing about half EI. Tank temperature at a not so optimal 27 degrees.

We are all aware that one tank is no scientific experiment, so all that I learn should be taken with a grain of salt. Also, I am definitely not a top scaper and my observations may not be relevant to the real connoisseurs on this forum.
With all these caveats, my take away after more than 2 months is that 15 ppm CO2 gave me less plant growth, but overall I can hardly see any compromise compared to the 1.5-1.6 pH drops (yellowish 4 dKH drop checker) that I did in the past. Perhaps I have been lucky, perhaps my tank balanced on a knife edge yet never fell off, or perhaps it was good maintenance and low waste organics. Who knows, but I did not come to regret this experiment at all.

A few days ago I have modified my CO2 Spray Bar to a smaller size, giving me a lower stabilised injection rate in overflow mode. I am now using a drop checker at 1.6 KH, which should give lime green at about 10 ppm CO2. Drop checker is green, perhaps lime green but definitely not yellow. I believe I am now at 10 ppm CO2, perhaps slightly less.

I have really been contemplating what to do with light. Nearly all experienced hobbyists would advise to lower light, but I am really fascinated by @sudiorca result and his theoretical explanations. So I have decided to keep my light full throttle, and only intervene if I see catastrophe developing. I keep ferts the same, and especially during the transition period will do meticulous maintenance to try and avoid an algae invasion.

I can't say that I am very confident this will work, but it is worth the try. I will intervene when things go wrong, my tank is in the living room and my fan base will not appreciate an algae farm. If it goes well, then I'll probably keep it like this for at least a couple of months to better understand this low CO2 and highish light setting.

 

[Yugang]

A few days ago I have modified my CO2 Spray Bar to a smaller size, giving me a lower stabilised injection rate in overflow mode. I am now using a drop checker at 1.6 KH, which should give lime green at about 10 ppm CO2. Drop checker is green, perhaps lime green but definitely not yellow. I believe I am now at 10 ppm CO2, perhaps slightly less.

When experimenting with CO2 I usually try to keep as much healthy plant mass as possible, avoid touching the substrate and do proper maintenance with big water changes. So far I have been able to keep algae under control, including BBA.

30% change in injection, from 15 to 10 ppm CO2 is quite a bit and will give a shock to the tank for the first week or two. As I wanted to have a good baseline for my observations what will happen with the 10 ppm I have still taken the decision to do quite some pruning, and while uprooting stems I had to touch the substrate as well. The water has not yet completely cleared up.

So here is my tank for comparison what will be happening in the next weeks and months under 10 ppm CO2 and full light. If I can keep it like this I will be very happy, and may not want to look back. Worst case, I go back to the 15 ppm CO2 that gave me the tank below.

 

[Yugang]

A quick update after weekly maintenance and water change. Slow growth, especially given the fact that I have not reduced light intensity, and some plants have suffered a bit when reducing CO2 from 15 to 10 ppm. Wallichi seems to have accepted its new home, and shows relatively healthy tops again. Virtually no algae, or any signs of trouble yet.

I have decided to install my old water spray bar again, full tank length, as I like the flow pattern better than the FX4 outlet that is visible in the previous FTS. The compromise here is that the CO2 Spray Bar, visible on the top right, gets very little flow and gives a clearly lower rate of injection. My current best estimate, without having a full set of data, is that the rate of injection from a CO2 Spray Bar under strong flow, compared to very little flow is about a factor of 2. So I changed from a 10 cm CO2 Spray Bar to 20 cm length to compensate for the low flow, and am back again at about 10 ppm CO2.

 

[Yugang]

I am now 3 weeks into my experiment with 10 ppm CO2, while keeping the light at full intensity.

I start seeing part of the picture, but would definitely think that more time is needed to see how the tanks evolves. I have been very careful with maintenance initially, as I was concerned that the tank might spiral out of control after depriving it of CO2. Last week I did some major maintenance, taking about a quarter of the soil out, cleaning it and back into the tank, and I can't complain about the robustness of the tank so far. I have seen one strain or thread algae, I have not had that for a long time, but hope that will not develop into an issue. Overall the tank seems to have stabilised very well, and until now I notice hardly any compromise (other than growth speed) as compared to higher CO2 ppm.

Many questions remain. How will the tank develop over the next months? How critical is the relatively high light intensity for success? When I buy new plants, how easily will they adapt to submerged and a new environment? Is there a chance that the tank will be less robust, ie recovers less well from issues? How much 'luck' is involved, or is my experience typical and easy to replicate?

I am not saying that I don't like pumping 50 ppm CO2, especially now that is so easy with a horizontal reactor. But what I like about my current experiment is that I don't need a reactor at all, use only 1.2 bps CO2 per second for overflow mode on a 50 gallon tank, have a more reasonable growth rate and virtually no compromise with regard to the tank's appearance. For me this looks and behaves like a full high tech, yet at a reduced cost and complexity.

 

[Yugang]

I'm going to try and focus a bit more on the scaping, and am especially interested to explore how new plants added to my tank adapt. I have no doubt that an abundance of CO2 helps a plant to acclimatise and overcome challenges, but would be interested to discover the limitations of 10 ppm CO2.

Yesterday I rescaped, and tried not to disturb the tank more than necessary while adding some 5 new plant species. In this phase I am interested in stability and have the plants succeed. The next weeks I'll try to grow these new plants out, and see if I can make the scape look a bit better.

Hong Kong is still warm, even in October, and tank temperature is 28 degrees C / 82 F. Light full intensity, and as usual dosing around half EI.

 

[Art]

Hey @Yugang, interested to see how this goes for you. Thanks for posting.

I too am making a change to my tank. I've accepted that my life requires me to balance the time I spend on the tank (read "spend less time on it"). It has been a difficult decision for me because I really do love the look of the garden style. The reality is, however, I don't have the available time to consistently trim, replant, etc in order to keep it looking the way I want.

As many of you know, when your tank doesn't look the way you want, it leads to frustration and mental angst. Not what I want from my planted aquarium.

So, all that to say, stay tuned for a re-scape this weekend pointing in the direction of middle earth.

 

[Yugang]

"spend less time on it"

So, all that to say, stay tuned for a re-scape this weekend pointing in the direction of middle earth.

Have you decided yet what will be your approach?

For a tank that needs less maintenance I could see various different strategies. Go low tech. High tech with a selection of plants that don't grow fast. High tech with lower light, but still plenty of CO2 and ferts. To mention a few.

My experiment, low CO2 yet full light and ferts, is mostly because I feel that @sudiorca method hints that perhaps we could have a tank that looks and feels like high tech, yet with much less CO2 than what is mostly recommended for high tech. I've now been experimenting for three months, first at 15 ppm CO2 and later further down to 10 ppm, and I am not disappointed with the results. One of the observations that is surprising for me is that a very strong reduction of CO2 ppm, like 50-80% reduction, gives so little changes in the plants (as long as light and ferts are unchanged), and for most plants around 50% reduction in growth rate, but not more than that.

Even if the low CO2, high light, approach turns out to work well, how many hobbyists would think this is a better approach than just larding on 30 ppm CO2 and more? Maybe cost savings? Fish and shrimp health? It will reduce the time spent on the tank maintenance., but less than I had hoped for.
Is it perhaps a solution looking for a problem?

Back to my question @Art , what approach will you be taking?

 

[Art]

Is it perhaps a solution looking for a problem?

Hmm, I've been thinking about this question a lot on several fronts lately. I'm not sure in this case.

My particular problem has been that my available tank time is inconsistent given my current lifestyle. My work takes me away from home unexpectedly. Sometimes a couple of days, sometimes for weeks. Layer on that I'm an empty nester and we like to travel, consistency goes out the window.

Up until this point I've tried to fight it using automation. While it's been a partial solution, it doesn't replace being there. So, I've taken some wise advice and am accepting my reality. I will try to make my tank work in a way that fits my reality.

I plan to maintain automation but go middle energy using CO2, medium light and medium ferts. My plant choice is switching from pure stems to slower growing epiphytes, crypto-cor-i-knees, mosses and few grass-like plants that will result in easy trims as needed.

I will post more details in my Art's Tank Journal and will post a summary here to keep this thread going for people to read.

 

[Yugang]

An update on my 10 ppm CO2, medium-high light, experiment.

Having started very conservative, trying to avoid bad surprises, I've now cleaned up about half of the substrate, uprooted most plants and done a rescape of the middle, and am now discovering how new plants will adapt to this environment. When doing some major work, I avoid disturbing the rest of the tank, hence the jungle on the right remains untouched and hopefully helps me with tank stability.

So far, perhaps surprisingly, it all seems to work very well despite the 'suboptimal' CO2. Only 1.2 bps CO2 on a 50 gallon tank, CO2 Spray Bar in overflow mode, but CO2 on 24/7 for optimal stability. Full intensity light, around 100 PAR, is now on for 11 hours, to help me make best use of experiment time. 27 C / 81 F, which is a challenge in itself.

This is a time stamp on this journey. Some plants have shown they are perfectly happy after adaptation, some others we'll see how it develops. No significant algae or other surprises.

An evening shot, as I like the relaxed mood with fish playing in the dimmed light on a HK Saturday night.

 

[Joel Armstrong]

An update on my 10 ppm CO2, medium-high light, experiment.

Having started very conservative, trying to avoid bad surprises, I've now cleaned up about half of the substrate, uprooted most plants and done a rescape of the middle, and am now discovering how new plants will adapt to this environment. When doing some major work, I avoid disturbing the rest of the tank, hence the jungle on the right remains untouched and hopefully helps me with tank stability.

So far, perhaps surprisingly, it all seems to work very well despite the 'suboptimal' CO2. Only 1.2 bps CO2 on a 50 gallon tank, CO2 Spray Bar in overflow mode, but CO2 on 24/7 for optimal stability. Full intensity light, around 100 PAR, is now on for 11 hours, to help me make best use of experiment time. 27 C / 81 F, which is a challenge in itself.

This is a time stamp on this journey. Some plants have shown they are perfectly happy after adaptation, some others we'll see how it develops. No significant algae or other surprises.

An evening shot, as I like the relaxed mood with fish playing in the dimmed light on a HK Saturday night.

View attachment 6347

I love following along on your tank here Yugang.

It's great to see your experiment with what's considered 'suboptimal' CO2 combined with your level of lighting.

How long have you been providing 11 hours of light for?

I definitely agree, very relaxing looking tank, and I think the colours are just beautiful.

Fantastic!

 

[Yugang]

How long have you been providing 11 hours of light for?

I had full light for 10 hours and brought that to 11 hours a week ago.

When I started experimenting with low CO2, 3 months ago starting with 15 ppm, I was concerned about the light intensity as it goes against most conventional wisdom in the hobby to reduce CO2 but not light. Over the last months I have build confidence that at least in my tank (who knows what other parameters are at play) I get away with it and have not had any bad experience. So I am now pushing the limits a bit further and working from the assumption that I give the tank all the light I have, and for a longer period as well.

The last two weeks I bought several new plants, trying to make the scape a bit better but also to find out if there are any plants that really don't like what I am doing. Following the inspiration from @sudiorca I am now hoping that more and longer light will help the plants with energy to adapt to their new home and grow a bit faster into a nice scape. I may up the lighting period to 12 hrs if everything continuous to go well. In the evening I have a couple of hours dimmed and relaxed light, I don't count these in the lighting period. My tank is fully dark for 10 hours.

 

[Joel Armstrong]

I had full light for 10 hours and brought that to 11 hours a week ago.

When I started experimenting with low CO2, 3 months ago starting with 15 ppm, I was concerned about the light intensity as it goes against most conventional wisdom in the hobby to reduce CO2 but not light. Over the last months I have build confidence that at least in my tank (who knows what other parameters are at play) I get away with it and have not had any bad experience. So I am now pushing the limits a bit further and working from the assumption that I give the tank all the light I have, and for a longer period as well.

The last two weeks I bought several new plants, trying to make the scape a bit better but also to find out if there are any plants that really don't like what I am doing. Following the inspiration from @sudiorca I am now hoping that more and longer light will help the plants with energy to adapt to their new home and grow a bit faster into a nice scape. I may up the lighting period to 12 hrs if everything continuous to go well. In the evening I have a couple of hours dimmed and relaxed light, I don't count these in the lighting period. My tank is fully dark for 10 hours.

I like to see, and hear about different ways to manage a planted tank..

Very well done

 

[Count Krunk]

Very interesting thread. Tank is looking great @Yugang .

 

[Yugang]

Four and half month into my experiment: 10 ppm CO2 24/7, 100 PAR and 50% EI Ferts. Temperatures got a bit lower recently in HK, more like 25C / 77 F.

If I had expected or hoped for some surprises when lowering CO2, it did not happen. The best I can summarise my experience is that growth is a bit slower, but other than that I find it really hard to pin point where my plants are doing less well, while I am now injecting less than 20% of what I used to do. Perhaps some plants that are struggling a bit would be more vigorous with more CO2, but I have always had a few plants not so well for no particular reason, while most are doing well.

I am contemplating what's next. I may just stick with this 10 ppm CO2 approach indefinitely with the arguments that

• I pay no attention at all to my CO2. Inject 24/7, because who cares at only 1 bps. Perfect stability.
• No need pH probe, as my stability is automatically optimised by overflow mode, as well as 24/7 injection. I verify my drop checker, which is always the same colour, no matter what time of day.
• No need for a reactor, I just use a simple 20 cm CO2 Spray Bar in overflow mode.
• My regulator is really not very stable, but I don't care as the overflow mode stabilises CO2.
• I don't expose my fish and shrimp to high CO2, or CO2 variations and hope that this is more comfortable for them
• My plants grow a bit slower, therefore lower maintenance
• No algae worth mentioning, although I do sometimes remove some BBA from hardscape.

My tank, at least how I perceive it, looks and feels like uncompromised CO2 injected, and I believe the limitations are more a result from my limited skills than anything related to low CO2. I do love my reactor, and it is interesting to push more CO2 again and see if I could bring the tank and my skills to a higher level.

Not sure yet what is next ....