Targeting fast or medium or slow growth?

[Yugang]

Context

Amongst high tech tankers, there seems almost a consensus that more CO2 injection gives better results, although also here the law of diminishing returns seems to apply: once CO2 is sufficiently available to the plants at a given light level, a further increase will not help much.

While for beginners a 1.0 pH drop is often recommended, experienced scapers often prefer to push with light intensity and pH drops exceeding 1.2 or even above 1.5.

Not many seem to be inspired slowing down a tank, minimizing CO2 injecting and/or light, and it may be interesting to understand why that is.

Driving on the fast lane is also a bit of a compromise. Any additional 0.3 pH drop (for example from 1.0 to 1.3) corresponds to 100% increase in CO2 ppm and similar increase of CO2 consumption and expenses. Plus, fast growing plants will require a lot of pruning, and the tank will soon look like a jungle if a pruning session gets skipped when life is too busy.

I have been pushing 1.5 – 1.6 pH drops for a long time, but am interested to explore the benefits of more lean CO2 dosing. I am now around 1.1, and at least with my limited skills do not really observe significantly less healthy plants than at higher CO2 ppm. My tanks growth rate is still a bit too high for me, and I would be interested to learn from fellow hobbyists, or explore myself, how I can slow down my tank, less light and less CO2 up to the point where I have a nearly uncompromised plant health, yet at reduced CO2 consumption and reduced pruning.

This poll is a bit experimental, but I hope it triggers some useful discussion. In the poll I used the growth/pruning rate as the key, which may or may not be a smart choice.

What would be great to learn:

• Fast lane (more than 20% of total plant mass pruned weekly), medium growth rate (10-20%) or slow lane (10% or less of total plant mass pruned weekly)
• Any data on CO2 ppm and if possible lighting PAR.
• What have been the trade offs and consideration when deciding for CO2 ppm and light intensity. Was it just a best guess, or a conscious choice?
• Any successful or unsuccessful attempts to achieve similar results with a lower growth pace (lower light and lower CO2 ppm) in the tank?
• What is believed to be the minimum CO2 ppm (let’s say expressed as it’s pH drop as a proxy) that allows for a virtually uncompromised high tech tank? How would we observe the tank starts deteriorating below this point?

 

[BigWave]

Light is the determining factor here. Lower light intensity and growth will slow down. Having algae problems, lowering the light intensity helps due to the plants being more able to get all the nutrients and CO2 need to sustain growth. Basically your matching your nutrient intake with the lower light which balances the system out. If you have high light and arnt feeding / dosing adiquitely you will see growth problems and also faced with the constant algae battle. Algae will most definetly take advantage of the situation or should i say inballance. If your limiting CO2 growth will slow down due to the plants not being able to get the need carbon. In essence your starving them of said nutrient so stunting, twisting leaves, poor new shoot development etc.
People dont realize that as the tank grows you have to feed it more. Increase that dosing and CO2 consumption. In stead of that 5 ml daily now you have to dose 10 or even 15mL daily to keep up. The more plant mass you have the more the tank is going to eat. The same goes for when you trim. What do you think happens if Im dosing 1 1/2 times EI with a very full tank say 80% plant mass then all of a sudden trim or butcher it down? Now you have 40% plant mass but are still pumping in fertz and Co2 at same levels as before. There is good reason the ADA dosing approach targets specific time frames / periods of the tanks life.
There is a huge difference between the general USA (west) vs European / Asian (East) way of dosing and keeping tanks. I do not know why but most in the US tend to dose per EI standards. Id say 85% of the commercial fertz are targeted to this approach. We blast CO2 like its no big deal. The other side of the hemisphere doses very lean and does not lard on the CO2. This is why you see all the posts about bubble counters and the like. The fertz are also targeted to this approach. Look at Masterline, Advanced Planted Tank, Fertilizanti etc they are all lean.

 

[Yugang]

Light is the determining factor here

Agree, the amount of light coupled with sufficient CO2 and nutrients, plus temperature, drives the growth.

I guess what I am aiming for with this thread is to discover why we are mostly driving for high light and high CO2, therefore high growth, and not more often moderating growth to a level that is more economical (light energy, CO2 consumption, pruning time, expenses). I am also referring to the thread "What do you spend most money on", where energy and CO2 score highest in the poll.

Could we enjoy same success at slower speed, approaching low tech, or do the best tanks always need the high energy. In other words, for really good tanks, can there be a compromise between high tech and low tech, and how far can we push the limits (down) without compromising on the plants ?

Note: I have tried to replicate what @sudiorca is doing with his fantastic non CO2 supplemented tanks, but believe that my tanks 84-85 F temperature contributed to my failure. I have seen a large and beautiful display tank in a non air-conditioned shop in HK, likely at same temperature, with just a small CO2 diffuser. Could it be that just a little of CO2 supplement helps to overcome the challenges of non supplemented low tech?

 

[Art]

Thanks for posting this @Yugang, should make for a good and thought-provoking discussion.

I think everyone will have an opinion here except for the newbies. The newbies will likely just want to be told what to do to get a nice tank going without algae. However, for more experienced folks, I think we each will have a different approach.

Mine is based on my current interest in stem plants and my gear choices. I aim for a moderate growth pace because I think this gives my tank the best result and doesn't require multiple trimmings weekly.

A few thoughts. First and foremost is that I think we need to think of a tank depending on its plants. What we want to achieve is a tank that is not "limited" based on its plants. For example, X amount of CO2 may be too little for fast-growing stems but just fine for slow-growing anubias. So, provided we are not limiting the tank, then you can control the amount of CO2, light and fertilizer to manage growth rate.

Limiting, in this case, is not providing the adequate amount necessary by the tank's plants. This amount is variable for each tank and we must all find that point through experience with the tank.

Once I have a sense for the amount of CO2, light and fertilizer I need to keep the tank healthy, then I usually think of lighting (like @BigWave said) as what will throttle rate of growth. Kinda like the accelerator in the car.

You can have the accelerator floored but without gas, you're going nowhere. The gas in my example is CO2 and fertilizer. I will focus on having enough CO2 and fertilizer and then adjust growth mostly with light level.

But, this is just me. Would love to see what everyone else does.

 

[Yugang]

I think everyone will have an opinion here except for the newbies.

I agree to everything you say @Art . One takeaway for me, at least so far, is that even the majority of experienced hobbyists don't find this a very interesting topic. The topic of this thread is not how we tune in CO2 and light, or use light as the accelerator, but it is the question why we think more is better. For most of us this is a non issue, but I am stubborn like to explore and learn.

X amount of CO2 may be too little for fast-growing stems but just fine for slow-growing anubias

When as usual we provide our plants with 'unlimited' CO2 and light, some will live up to the expectation and be considered 'fast growing stems'. Is this indeed a built-in feature of this plant species, or a result of the conditions that we created? Is it there a possibility that we could make 95% of plants perfectly happy at 15% ppm CO2 and medium light, and with that create a great looking high tech tank?

I need to refill my CO2 about every 3 months, for my 50 gallon tank and about 1.1 pH drop from degassed. I have already slowed down growth since I came from 1.5-1.6 pH drop, but still feel 4-5 days after a maintenance session that many plants are ready for the next haircut to bring the tank in optimum shape again.
Now consider that I bring down my pH drop from 1.1 to 0.5. This would correspond to about 4 times saving of CO2 consumption. I would refill my bottles only annually, and I hope with slowed down growth my tank always looks as if it just had its last pruning session.

Here is my tank, no ambition to win a competition but happy with it. Could I maintain a similar level at a much reduced growth speed, lower light and lower CO2 injection? How far can I push down, lower and lower CO2 injection?

 

[Art]

but it is the question why we think more is better. For most of us this is a non issue, but I am stubborn like to explore and learn.

I'm very similar to you. I ask questions. Some like it, some don't. It's OK. There are always people that think like you do and appreciate a nice conversation and some thoughtful discussion. Thanks for bringing this up.

Could I maintain a similar level at a much reduced growth speed, lower light and lower CO2 injection? How far can I push down, lower and lower CO2 injection?

These are great questions. IMHO, the answer depends on who is asking.

For you, these questions may be very meaningful and a good goal. For others, there is no need to ask these questions as their objective is not to reduce the work or the CO2 consumption.

You ask the question, why is more better? My 2 cents is that more may be better or it may not be. It depends on your perspective. Perhaps, we should ask, what is better for you?

You may be at a life point where you need to keep plant growth healthy but slow. Or, you may want to truly push your plants to be at their optimum growth level. This is the beauty of this hobby. You make it what works for you. The common theme is healthy plants. But, after that is satisfied, pace of growth is entirely up to you (mostly).

I am no Tom Barr, Vin Kutty or Gregg Zydeck when it comes to growing healthy plants. I am also no Mike or Jeff Senske, Josh Sim or Masashi Ono when it comes to aquascaping. That said, I have been doing this since the mid-1990s and now truly find joy in the craft of horticulture.

I enjoy tuning out the noise of life and fully focusing on the craft of trimming, vacuuming and cleaning my tank. It's a mindful meditative practice that is good for me. I also don't fight against my choice of doing it weekly. When life becomes busy and I can't trim a particular week, it's OK. I don't obsess over it.

I find this creates a harmony between the tank and myself that is very rewarding for myself and the ecosystem that is my tank.

Sorry about going meta (I think that's what my kids would call this post), but your probing question got me thinking and appreciating where I am now in my planted tank journey.

 

[Yugang]

I am no Tom Barr, Vin Kutty or Gregg Zydeck when it comes to growing healthy plants. I am also no Mike or Jeff Senske, Josh Sim or Masashi Ono when it comes to aquascaping

They, and a few others of comparable expertise, usually lead by example with high light, high CO2 and all else that is thought to be needed for a top tank. Only @sudiorca works at a no-compromise level without CO2 injection, but he needs low temperature for that. How much could we learn if these most experienced scapers demonstrate what is possible on the continuum between low tech and high tech, and break the conventional wisdom that the world is divided between high tech and low tech?

This was really the aim of this thread, trying to learn from others who have already tried 'lean CO2 injected tanks', succeeded or perhaps less successful.

I am using my Horizontal Reactor in overflow mode and would have to adjust the size again if I want to further reduce CO2 injection. Besides that, the tank would suffer if I again start reducing CO2 significantly. Anyway, I have adjusted my light level down by 20%, and who knows when I let CO2 follow ...

 

[Art]

@Yugang there have been people I know that believe 30 ppm CO2 is too high. I know many in Europe/Asia believe it’s too high and run closer to the 10-15 ppm level. Marcel Golías did some experiments in 2017 about the management of CO2 and his thoughts on the subject.

 

[TRyan]

@Yugang there have been people I know that believe 30 ppm CO2 is too high. I know many in Europe/Asia believe it’s too high and run closer to the 10-15 ppm level. Marcel Golías did some experiments in 2017 about the management of CO2 and his thoughts on the subject.

I've been curious about this. If 30 ppm CO2 is a 1.0 pH drop, is 15 ppm CO2 going to equal a .5 pH drop? How is one to tell?

 

[Yugang]

I've been curious about this. If 30 ppm CO2 is a 1.0 pH drop, is 15 ppm CO2 going to equal a .5 pH drop? How is one to tell?

We can start with one caveat, this is that pH drop is used as a proxy for CO2 ppm, and when we dive deeper in the scientific basis there is a problem with stating that 1.0 pH drop corresponds to 30 ppm CO2.

An alternative approach to CO2?

Inspired by the thread on CO2 controllers, and @Art experiment with modified pH probe / drop checker, I came up with what is to the best of my knowledge a new approach for our hobby. I am not strong on the chemistry of CO2 in water, so it would be great if others chime in and comment if this...

scapecrunch.com

As most of us can't measure dissolved CO2 ppm directly, we could take practical approach and refer to pH drop while accepting that we actually do not know the correct CO2 ppm. What we do know however is that CO2 ppm and pH drop have a logarithmic relationship. As an example, 0.3 change in pH drop corresponds to a factor of 2 in CO2 ppm.

So keeping it simple and ignore the complexity above - If you would assume that 1.0 pH drop corresponds to 30 ppm, this is a big 'if', then 0.7 pH drop would correspond to 15 ppm CO2 and 1.3 pH drop would correspond to 60 ppm.

 

[TRyan]

We can start with one caveat, this is that pH drop is used as a proxy for CO2 ppm, and when we dive deeper in the scientific basis there is a problem with stating that 1.0 pH drop corresponds to 30 ppm CO2.

An alternative approach to CO2?

Inspired by the thread on CO2 controllers, and @Art experiment with modified pH probe / drop checker, I came up with what is to the best of my knowledge a new approach for our hobby. I am not strong on the chemistry of CO2 in water, so it would be great if others chime in and comment if this...

scapecrunch.com

As most of us can't measure dissolved CO2 ppm directly, we could take practical approach and refer to pH drop while accepting that we actually do not know the correct CO2 ppm. What we do know however is that CO2 ppm and pH drop have a logarithmic relationship. As an example, 0.3 change in pH drop corresponds to a factor of 2 in CO2 ppm.

So keeping it simple and ignore the complexity above - If you would assume that 1.0 pH drop corresponds to 30 ppm, this is a big 'if', then 0.7 pH drop would correspond to 15 ppm CO2 and 1.3 pH drop would correspond to 60 ppm.

Thank you for this very detailed answer! I'll check out the article.