# RO & CO2



## hotweldfire (3 Jun 2011)

I've read Tom Barr's article on non-CO2 methods and worked my way through this sub-forum and have to say I'm very tempted to attempt this method on my new nano. I guess the thing I'm struggling with, which appears crucial to the method, is the lack of water changes. 

Whilst this is one of the advantages of this method it goes so against the grain of what I've learnt as an aquarist it's almost like losing my religion. My understanding of this is water changes result in a quick increase in CO2 levels in the tank which plants will try to adapt to in order to exploit it. When that burst is gone they will struggle to adapt back and the algae will move in to fill the gap.

Found this thread very interesting:

http://ukaps.org/forum/viewtopic.php?f=27&t=6638

I understand that tap water will have different levels of CO2 than the tank. Does this hold for RO? What about RO sitting in a bucket over night?

I assume the answer is yes as there's nothing in the RO (e.g. fish, soil in substrate, decaying organic matter) producing CO2. In which case I'd be removing CO2 from the tank rather than adding it.

If so, are the levels likely to be so different as to produce algae problems? Especially if I'm not using soil but something like nutrasoil or aquasoil?

Secondly, how do you go about starting it with an active substrate like nutrasoil which I assume, like ADA As, leaches considerable amounts of ammonia into the tank on startup? Surely this requires frequent and large water changes which will set the plants up to depend on higher co2 levels.


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## ceg4048 (4 Jun 2011)

hotweldfire said:
			
		

> ...the thing I'm struggling with, which appears crucial to the method, is the lack of water changes.
> 
> Whilst this is one of the advantages of this method it goes so against the grain of what I've learnt as an aquarist it's almost like losing my religion...


Well the aquarist religion is filled with a lot of dogmatic principles that are not based on facts. Barr cleverly de-constructed each principle to find the truth and constructed new principles over the rubble using the building blocks of the scientific method.

It may seem patronizing, but in order to start at the most fundamental level, it's important to understand exactly why we do water changes and to know just exactly what it is that we are changing. You do realize for example that there is really no point in changing the actual water molecules (H2O)? Water molecules don't go stale, or don't spoil or anything like that. So what we're removing in a water change are the solutes dissolved in the water. These solutes constitute only a tiny fraction of the total mass of the removed water. Despite their minority in mass, they are highly toxic. So the idea is to figure out what the constituents are, figure out their toxicology, and then figure out what happens to them in the planted tank.

Of course the most toxic constituent is Ammonia. It's origin is in the urine, faeces, animal and vegetable matter in the tank. Bacterial action starts the chain of events. In an unplanted tank the presence of ammonia is a hazard "fought" strictly by aerobic bacteria (we hope). In detoxifying ammonia the penalty is a reduction in the Oxygen levels. In an unplanted tank, we have chosen for our fish the lesser of evils - hypoxia instead of ammonia poisoning.

In a planted tank however, the plants uptake ammonia directly, removing it from the scene at only a slightly less rate than the filter bacteria. As a result of the uptake the plants reduce the amount of bacteria needed to detoxify, and they also significantly short circuit the Ammonia==>Nitrite part of nitrification, which reduce the amount of Oxygen pulled from the water column by the bacteria to perform this conversion. On top of that, the plants themselves produce Oxygen during the day. So the total amount of Oxygen available to fish is significantly higher. So the two most toxic components in polluted water is immediately addressed. Whatever ammonia escapes the plants and is used by bacteria, well, there is extra Oxygen so the fish are not robbed and the NO2=>NO3 part of nitrification is not a problem because the plants will easily uptake NO3 as well.

In fact, this system is so amazing that the plants will often run short of Nitrogen, and this is why Barr's method calls for an occasional (weekly or bi-weekly) addition of minor amounts of NPK.

Depending on the plant species, they will also remove other elements from the water such as Calcium and Magnesium. They do such a good job that it's often necessary to add these components along with NPK.

The solids that are pumped into the tank by fauna and flora, such as fats, proteins, enzymes and carbohydrates are also broken down into their constituent parts and are then removed from the water column leaving nothing but empty husks seen as detritus. If they become unsightly then they can easily be removed, and that's what the occasional water changes are used for in Barr's non-CO2 method.

There is no need to change your water with RO if you decide that you want to do water changes anyway. Tap water will outgas CO2 overnight. In any case the idea of the method is to minimize the need for water changes, so it's up to you. AS discussed in the thread you can change the water during non photoperiod, you can let it sit and outgas, you can just top up, you can change only small percentages - you can do anything you want, but you don't have to do anything because the plants are doing your water change for you. That's the point.

Hope this helps.

Cheers,


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## CeeJay (5 Jun 2011)

Hi hotweldfire


			
				hotweldfire said:
			
		

> I guess the thing I'm struggling with, which appears crucial to the method, is the lack of water changes.


Trust me, it works   
One never 'truly believes' until you see it for yourself.
One of my tanks is 'low tech', in fact it should be called 'no tech'  because I don't do anything to it apart from clean the filter now and again and top up any water loss, which is very rarely, as mine has a lid on it.
The tank has been running for nearly 2 years and has only had one water change since it was set up   , and that was after a BGA attack in the beginning, which I now know was caused by low ferts. Once I got that bit sorted, everything has been fine ever since   . It has also still got most of the original fish in it, just had two guppies die on me, at different times, so obviously not related to any water quality issues.
Plants are slow growing, and some of them have taken a slightly different form to their CO2 supplied cousins, which is to be expected, but this is a seriously low maintenance tank     I would offer to post up a picture, but the true scapers round here would banish me from the forum as it's a bit of an overgrown jungle   
One thing that stands out a mile is the fishes behaviour. At feeding time in my CO2 tanks, the fish are like psycho's, gobbling up food at 100mph. At feeding time in the low tech, the fish just plod about, munching odd morsels here and there  :? 
All I know is the plants and fish are healthy with very little maintenance, so if that's your goal, I say go for it  Feed the fish daily, feed the plants once a week, clean the filter (when I get round to it  ). How simple is that?


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## hotweldfire (5 Jun 2011)

OK, I'm sold.

CeeJay, that was a very convincing testimonial.

CEG, I have a confession to make. I'm actually a research scientist by trade in psychology and psychiatry. I work for an organisation that is about evaluating interventions and promoting evidence based practice. What's interesting is the amount of crap that is done to people in my field by dodgy interventions supposedly based on good scientific principles. Of course they're actually interventions based on a fundamental misunderstanding of good scientific principles and aren't evidence based at all.

I think the parallels with the planted tank world are quite striking. People have adopted strategies for wont of solid understanding themselves because they have been pushed by people with a degree of authority. What gives them that authority is some success with their methods. But their methods aren't really evidence based, they've just been successful within certain parameters and are likely to fall flat in other parameters because they're dogma.

So I hope, given that context, you'll understand how much I appreciate your post. It's an argument properly based on first principles and I find it incredibly useful. Much respect mate.

So, that leaves me with one issue: how do I start this tank up? Nutrasoil will leach a bunch of ammonia into the tank. The sponge for the new filter is currently nestled amongst some siporax in the external of my main tank so should be mature in a week or two. 

Do I just lob the plants, water and filter in and assume they'll sort themselves out or is that asking for a major algae bloom? 

Or are lots of initial water changes necessary before gradually weaning the tank system off them?


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## CeeJay (5 Jun 2011)

Hi hotweldfire.

Great reply.
My start up was slightly different in the fact that it has 'el cheapo' inert substrate with Osmocote underneath, so I never had the Ammonia leaching problems. The only jump start I gave it was using mature filter media, which would obviously help in your case. 
I would suggest standard start up practice, e.g. short lighting periods, no livestock etc. etc.
What you could also do as a temporary measure is chuck in some Egeria Densa. Not the prettiest plant on the planet, but a true workhorse. This is sold in one of my LFS's to 'prevent algae'. The real reason it helps to 'prevent algae' is it's ability to use vast amounts of Ammonia (sound familiar, going back to your post   ).
You can always take it out after a few weeks and then 'scape' it how you like. That's what I promised myself I would do, but it's still in the tank nearly 2 years later


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## faizal (6 Jun 2011)

Hey Ceejay,...wouldn't it be a great idea if we could get all the members to show us their non co2 tanks,...it would give us beginners a much better idea on the aquascaping aspect and plant choices that we could use & try for our non co2 tanks. 

There's so much I feel we could learn by looking at their tanks and aquascaping techniques in a low tech aquarium.

You'd probably think that your tank is not beautiful enough to post its picture but for someone like me (who's just coming into grips about planted tanks),...picture truly means a thousand words. So,.... pretty please  mate, 

Faizal


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## CeeJay (6 Jun 2011)

Hi Faizal

Mine's no aquascape by any stretch of the imagination  , just a tank full of plants   
Will try and post up some pics later on.


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## CeeJay (6 Jun 2011)

This one's for you Faizal   

Tank specs
95 litre
700lph External filter
200w Hydor in-line heater
No CO2
1 wpg, 7 hours a day
Ferts. James' All in One DIY TPN+ 40ml once a week   
No water change for nearly 2 years   

Plants
Limnophila Sessiflora (It got blown over by the filter so I left it there   )
Egeria Densa
Rotala Rotundifolia
Microsorum Pteropus
Microsorum Pteropus 'Needle Leaf'
Crypt. Wendtii Green
Crypt. Wendtii Brown
Crypt. Wendtii Mi Oya
Vallis. Spiralis
Echinodorus Rose (Not growing much, but also not dying   )
Echinodorus Osiris (Also not growing much, but also not dying   )
Hygrophila Corymbosa 'Compact' (the only one the Ramshorn snails eat   )

Livestock
Halequins
Pearl danios
Guppies
Neon Tetra
Ramshorn snails (lots)

So here's my 'no tech' tank

Left Side





Right Side




Front




Told you it was a mess


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## faizal (7 Jun 2011)

Thank you Ceejay!!!  

Such healthy looking plants!! Okay ,....so you didn't take the time to aquascape it,...so what? Your plants are looking amazing there. Dwarfism is supposed to be an expected trait in non co2 set ups,....correct me if I'm wrong please,...but your plants look huge there.

I could only imagine how that tank would have looked if you had actually aquascaped it, mate   !!!

Thanks again Ceejay  

Faizal


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## CeeJay (7 Jun 2011)

Hi Faizal


			
				faizal said:
			
		

> Dwarfism is supposed to be an expected trait in non co2 set ups,....correct me if I'm wrong please,...but your plants look huge there.


Some species stay small (Echinodorus in particular) and the Crypts are slow growing, but I have to uproot the Vallis now and again when it's runners grow in between the Crypts. The Rotala and Egeria Densa still have to be trimmed because they reach the surface, so they still attain their full height, just takes a lot longer that's all  
This tank was the result of a 'hi tech' strip down and the plants were just put in randomly, all over the place (as you can see   ). I just wanted to see for myself that 'it could be done'............and now I know it can


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## faizal (7 Jun 2011)

Ceejay,...did your Vals actually under go a severe initial melt down when you first planted them in that low tech tank? If so,...how long did it take for them to grow back new shoots? The reason i ask this is because some of the people I know have had Vallisneria in their non co2 tanks that underwent almost total meltdown ( I mean,...in a span of 2-3 weeks) & never re-grew back. 

Maybe their light levels were too high,......

P.S. --> Very sorry for the hijack


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## faizal (7 Jun 2011)

I know now that you have 1 WPG worth of lighting but what type of lights do you have on them please? T5,..T8


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## CeeJay (7 Jun 2011)

Hi Faizal


			
				faizal said:
			
		

> Ceejay,...did your Vals actually under go a severe initial melt down when you first planted them in that low tech tank?


No it didn't. However, the leaves that were near the surface did have an attack of BBA   , probably because of too much light and being dumped in a non CO2 environment, but the Ramshorns have munched it all and it hasn't come back  


			
				faizal said:
			
		

> I know now that you have 1 WPG worth of lighting but what type of lights do you have on them please? T5,..T8


Lighting is 1 x T8 tube on this tank.


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## dw1305 (7 Jun 2011)

Hi all,
My tanks are all low tech, heavily planted, no CO2 and nutrient depleted. Some of them are low light, but some are much more brightly illuminated including with natural light from the side, all have a covering of floating plants. I'm a fanatical water changer, with the proviso that I use rain water for my water changes, that it will be of a similar temperature to the tank water (re: Henry's law) and I only change a small amount (usually 10%) daily.

My tanks have a wide range of algae, covering all the groups, Chlorophyta, Rhodophyta, Diatoms and Cyanobacteria, but I rarely have very much of any of them and I can't remember ever having had an "outbreak" of any alga in an established tank. In my particular circumstances I'm not convinced by the "_fluctuating CO2 = algae_", although I have no experience of high tech., EI fertilised, CO2 rich tanks, where this may apply. 

From personal experience of both working with landfill leachate (a liquid with a very high BOD) and keeping low tech tanks, I think that A1Matt's point is the important one:


> Water turbulence on a non CO2 tank is a good thing because it will allow the natural equilibrium to be replenished much quicker. The plants will use CO2 and returning to equilibrium takes time so the water turbulence means it will happen much faster.


This would also be a reason why I'm also very keen on "wet and dry" trickle filters, which have an enormous area for potential gas exchange.

cheers Darrel


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## CeeJay (7 Jun 2011)

Hi Darrel
Nice to have your input here.


			
				dw1305 said:
			
		

> In my particular circumstances I'm not convinced by the "fluctuating CO2 = algae",


I am, honest, especially BBA in the high light, high tech tanks.
But what I am now convinced about too, is that BBA will appear if there is too much light and not enough CO2 in the high light, high tech tank. Not just CO2 being unstable.
I may be wrong, but it certainly appears that way in my tanks


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## dw1305 (7 Jun 2011)

Hi all,


> But what I am now convinced about too, is that BBA will appear if there is too much light and not enough CO2 in the high light, high tech tank. Not just CO2 being unstable


 Which is interesting, as my highest light tank is definitely the one with the most BBA in it. 

cheers Darrel


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## plantbrain (7 Jun 2011)

CeeJay said:
			
		

> Hi Darrel
> Nice to have your input here.
> 
> 
> ...



Plants will adapt to various CO2 levels.

Say 0-3ppm range.
and say 30-50ppm range etc.
Even middle ranges, say 15-20ppm.

Once cannot pull out light intensity independently, they ar elinked and this is BASIC stuff here, photosynthesis equation etc.

Light + CO2 + water(we got plenty of that)= sugars basically.

More light= more reductants(NADPH) and ATP's available to run more CO2 fixation.

If you run the CO2 all over the place, then the enzymes and the chemicals required to do this "work" cannot run at peak efficacy. Plants will chew up and dispose of excess enzymes if they are in excess and compete for energy and resources. they will make more if things become limiting. These adaptations have their limits and when they are exceeded, then algae seems to take a hold, looking for that window.

If you measure the amount of Rubisco in a plant grown in low CO2 vs high CO2 water, there is a massive significant increase in the plant grown in the low level CO2. If you take a plant that is grown in a high CO2 level, then switch to low CO2, it will do poorly. This is why higher CO2 and higher light tanks often have far more algal issues than non CO2, the other is simply the CO2 is more stable, even if limiting. There is no train wreck potential with the non CO2 approaches.

Growth is slow, demand is slow and the plants are adapted.

One of big issues, I think this applies to both CO2 (where CO2 is mildly limiting particularly and where biomass has increased a fair amount over time) and non CO2 tanks is competition between plant species. Lots of talk about algae, less about the plants  

I'd argue the plants are the focus and goal here, algae are secondary issues.
Much like weeds in farmland, if the crops are grown well, rotated well(pruned), then the weeds are rarely an issue.
The crops covers the weeds and the weeds die back once the crop has been well established. Corn etc is a good example. Others are not, like Rice. Flooding/drying and wet paddy culture helps though.


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## CeeJay (8 Jun 2011)

Hi all


			
				dw1305 said:
			
		

> Which is interesting, as my highest light tank is definitely the one with the most BBA in it.


These were only my observations. I may be barking up the wrong tree altogether. 

What I do know is that I have lowered my light intensity by around 50% for the last 6 weeks and no BBA. CO2 was left as it was. Although the BBA only seemed to affect the slow growing plants in high light areas. Now I know we have many other factors at play, e.g. bigger plant mass in 6 weeks, which affects CO2 delivery etc. etc. But as stated on here many many times, lower lighting certainly gives you more 'wiggle room'. 
I'm sorely tempted to get shot of my T5's 

Thanks for your input Tom. Interesting read, once again. 
Your input is always valued & appreciated


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## faizal (8 Jun 2011)

I was just wondering,....would these values seem okay for a non co2 tank with regards to PAR?

Substrate : 30-40micro molles/sec/m2
Water Surface: 100-110 micro moles /sec/m2

Are they too high for a non co2 set up?

I know that LCP for most plants are at 10-20 micro moles /sec/m2

So in a non co2 set up would these values be okay or should I lower it a bit further still?


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## ceg4048 (8 Jun 2011)

hotweldfire said:
			
		

> ..I have a confession to make. I'm actually a research scientist by trade in psychology and psychiatry. I work for an organisation that is about evaluating interventions and promoting evidence based practice. What's interesting is the amount of crap that is done to people in my field by dodgy interventions supposedly based on good scientific principles. Of course they're actually interventions based on a fundamental misunderstanding of good scientific principles and aren't evidence based at all.


Wow, powerful stuff mate. You've summarized the very essence of The Matrix quite brilliantly.



			
				hotweldfire said:
			
		

> I think the parallels with the planted tank world are quite striking. People have adopted strategies for wont of solid understanding themselves because they have been pushed by people with a degree of authority. What gives them that authority is some success with their methods. But their methods aren't really evidence based, they've just been successful within certain parameters and are likely to fall flat in other parameters because they're dogma.


Yes, that's right. Part of the problem is that our reaction to the product that is the planted tank is primarily emotional. This makes us susceptible to emotionally based arguments or propaganda, where we are less likely to question the validity of those arguments. Here is a classic example of a company, with establish authority in the field discussing some principles of lighting => Dennerle Aquaristik Lighting

In the opening statement it is argued that:


> Thunderstorms regularly darken the skies in the tropical habitats which are home to most aquarium plants,  It is thus advisable to give plants a break and switch the lighting off for between two and four hours around midday.


But where is the evidence? No data is provided and the logical leap between darkened skies and darkened aquarium is completely speculative. Someone just "came up" with this connection. It seems plausible, so all of a sudden, this becomes an authenticated fact by a well known aquarium plant company with no evidence whatsoever.

The opera continues with:


> In order to flourish, aquarium plants need plenty of light from the red colour range, with only a minimal blue component and minimal or no UV radiation. Algae, on the other hand, thrive above all in blue light and a high UV component.


Did they set up a series of tanks, some illuminated with blue and others with red, and then draw this conclusion based on the evidence of the results? No, someone just "reasoned" this out which somehow justifies the spectrum of the bulbs being offered for sale.

So the path to knowledge becomes a minefield and only the evidence of our own testing can confirm or refute the argument presented. Few bother to do this, so again, it becomes accepted as truth, when in fact it's complete rubbish.



			
				hotweldfire said:
			
		

> So I hope, given that context, you'll understand how much I appreciate your post. It's an argument properly based on first principles and I find it incredibly useful. Much respect mate.


Thanks mate. Freeing our minds from the tyranny of The Matrix is the most important step into the world defined by the most basic and repeatable axioms.



			
				hotweldfire said:
			
		

> So, that leaves me with one issue: how do I start this tank up? Nutrasoil will leach a bunch of ammonia into the tank. The sponge for the new filter is currently nestled amongst some siporax in the external of my main tank so should be mature in a week or two.


Well, further to what Chris mentions, there really are a couple of options. 
1. You can mineralize the Nitrogen in the sediment by baking it for a few hours. 
2. You can also dry start the tank for four or more weeks to get the sediment bacteria up and running. The bacteria do the nitrification which will significantly reduce the ammonia level. 
3. If you don't want to go through all that trouble, you can simply put the sediment in a bucket for that time and just cover it to keep it moist without any plants. You will still generate bacteria and nitrification of the ammonia.
4. You can also just chuck them in and with daily Liquid Carbon doses and then wean the plants off the carbon enrichment over a period a several weeks/months.



			
				CeeJay said:
			
		

> Hi Darrel
> Nice to have your input here.
> 
> 
> ...


The problem with this observation is that we don't always have the ability to measure the instability. It may not be obvious what the mechanism of the instability is. Furthermore we must consider that high light exposes the instability more so than lower light simply due to the fact that the commanded CO2 uptake rate is higher than under lower intensity light. Everything is higher and faster under higher PAR. It can easily be, for example, that the instability mechanism is the CO2 diffusion rate across the boundary layer and across the bio-film into the membrane. Under high lighting, the uptake rate may cause CO2 evacuation within the boundary layer and it may take time for this layer to become saturated again, possibly causing a cyclic CO2 loading instead of a chronic low CO2, which is more typically associated with hair/thread. I'm just speculating based on some of the data I've seen, based on my own empirical evidence, as well as based on adhering to the fundamental axioms.

Cheers,


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## CeeJay (8 Jun 2011)

Hi all


			
				faizal said:
			
		

> So in a non co2 set up would these values be okay or should I lower it a bit further still?


You could lower it further, or alternatively use some floating plants to diffuse the lighting further.



			
				ceg4048 said:
			
		

> The problem with this observation is that we don't always have the ability to measure the instability. It may not be obvious what the mechanism of the instability is.


I find this is certanly true of the planted tank.



			
				ceg4048 said:
			
		

> It can easily be, for example, that the instability mechanism is the CO2 diffusion rate across the boundary layer and across the bio-film into the membrane.


Now this statement would certainly answer some of my questions e.g. Why no BBA anywhere else?  :? 



			
				ceg4048 said:
			
		

> I'm just speculating based on some of the data I've seen, based on my own empirical evidence, as well as based on adhering to the fundamental axioms.


As you have done far more testing than I will ever do in my lifetime, I will always value your input. You've helped me no end on my journey into the planted tank world so far. Thanks Clive


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## hotweldfire (8 Jun 2011)

Two (related) arguments here, it seems to me. One is around what is the best way of ensuring highest CO2 levels in a non CO2 supplemented tank are. The other is about what causes BBA.

Re: the first, it appears to me that whether you think water turbulence is a good idea in a low tech tank is driven by whether you think there's more or less CO2 in the tank than in the surrounding air. If there's less then, yes, it would make sense to bring it back to a higher equilibrium by disturbing the surface and thereby drawing co2 from the air into the tank. If you think that the tank has more, which is what Diana Walstad appears to be arguing, then you should be doing everything you can to avoid it getting out therefore minimal water disturbance.

Re: the second, my experience tells me that fluctuating CO2 leads to BBA but addressing the issue doesn't necessarily deal with it and high light plays a part. I only got a serious BBA problem in my main tank when my crap regulator started playing up and ended up pumping a different level of CO2 into the tank every day. Suddenly it's all over my cyperus helferi. Which, by the way, is a slow growing plant nearest the lights. It's hardly anywhere else in the tank. I have done my best to deal with what I reckon is the main cause but it ain't going away. Once it's in it's a bugger to get rid of.

I'm sure Tom's right, plants will adapt to different CO2 levels. But when you massively increase growth with high levels of injected CO2 and high light there's no wiggle room. When your regulator is changing it's rate at 10-20 bpm a day (randomly in both directions) and you can't correct it you gonna have problems under high light.



			
				ceg4048 said:
			
		

> Wow, powerful stuff mate. You've summarized the very essence of The Matrix quite brilliantly.



Thanks. I finally get your Matrix reference now  



			
				ceg4048 said:
			
		

> Well, further to what Chris mentions, there really are a couple of options.
> 1. You can mineralize the Nitrogen in the sediment by baking it for a few hours.
> 2. You can also dry start the tank for four or more weeks to get the sediment bacteria up and running. The bacteria do the nitrification which will significantly reduce the ammonia level.
> 3. If you don't want to go through all that trouble, you can simply put the sediment in a bucket for that time and just cover it to keep it moist without any plants. You will still generate bacteria and nitrification of the ammonia.
> 4. You can also just chuck them in and with daily Liquid Carbon doses and then wean the plants off the carbon enrichment over a period a several weeks/months.



I fear after a couple of beers at lunch time I have chosen to do none of the above but have instead just chucked everything in and ran it. Would have used liquid carbon but have put a lot of coral pelia in there which I understand doesn't much like it.

Let's see what happens.  Probably a disaster. You can watch the car crash on my journal.


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## CeeJay (9 Jun 2011)

Hi hotweldfire


			
				hotweldfire said:
			
		

> Two (related) arguments here, it seems to me. One is around what is the best way of ensuring highest CO2 levels in a non CO2 supplemented tank are. The other is about what causes BBA.


Sorry for the hijack. We digressed  . 
As you can see, BBA was first mentioned by me when asked how did my Vallis. respond to being dumped in a non CO2 tank.
Apologies for that.
Still, some very informative reading, for me at least  



			
				hotweldfire said:
			
		

> I fear after a couple of beers at lunch time I have chosen to do none of the above


That made me smile


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## hotweldfire (9 Jun 2011)

Absolutely no need to apologise. BBA is a current concern of mine and not that off topic. Anyway, if I can encourage an interesting debate then I'm a happy chappy.


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## ceg4048 (9 Jun 2011)

You might find it useful to review the thread Co2 Fluctuations and BBA which talks about BBA and CO2 instability, and is basically the long version of what Tom just described in his post. We have to remember that the adaptability of the plants is also a key factor in the dynamic of BBA. Not all plants have the same adaptability and not all have the same efficiency of uptake. This inequality also applies to individual specimens within the same species based on their current health.

Cheers,


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## hotweldfire (9 Jun 2011)

Interesting read Clive, thanks. Am keen to continue that discussion but don't know if it should be off-topic here or thread necromancy there.

Returning to the problem at hand, the tank is up and running. There are not fish in there producing co2 and no fish food/waste producing NPK. The latter is not a problem for most of the plants I guess as they're getting what they need from the substrate. But not the coral pelia. Will it be ok for a few weeks without the nutrients that the fish will produce? Or should I start dosing something now? Dropped in 1ml each of green brighty step 2 and brighty k on startup but that won't help the pellia's NPK needs.

More importantly the CO2 issue. Clive, I am sorely tempted to try daily excel dosing in the short term and then wean off. Two reasons I'm hesitating:

1) I don't want something this toxic lying around with a 2 year old in the house. It will be out of reach but they're ingenious things 2 year olds
2) Coral pellia. I understand it doesn't fare well with liquid carbon. 

If I went for rec daily dose do you think it would be ok? Really do not want to lose it as it is glued in between the rocks and I can't replace without ripping up the whole scape as the rocks are supporting the substrate at the back.


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## dw1305 (9 Jun 2011)

Hi all,


> If there's less then, yes, it would make sense to bring it back to a higher equilibrium by disturbing the surface and thereby drawing co2 from the air into the tank. If you think that the tank has more, which is what Diana Walstad appears to be arguing, then you should be doing everything you can to avoid it getting out therefore minimal water disturbance.


This isn't quite true, she is arguing that minimal surface disturbance retains the CO2 released by natural processes in her organic matter rich substrates, and that the substrate is providing much of the CO2 that the plants are utilising, rather than the 3 or 4 ppm of CO2 from atmospheric diffusion (page 100 of "The Ecology.......Aquarium"). 

I've got a lot of time for her, but in this case I think that she is wrong, or at least that this isn't true for the vast majority of substrates. There is always more CO2 in the atmosphere (388ppm and rising by about 2ppm annually) than in the tank water, usually by at least one order of magnitude. In a modern home you could easily have 600 - 800ppm CO2 in the rooms. The solubility of CO2 is dependent upon all sorts of things, but at 25oC it is about 1.5g of* pure* CO2 in 1000g of H2O, but CO2 only forms at minute fraction of the atmosphere and saturation level is 0.43 mg/l (in pure H2O at 270C and 1 atmosphere pressure).

You would have gassed all of your inhabitants long before you got anywhere near 400ppm in a tank, it will depend on the fish (and the amount of dissolved O2), but some-one will have some figures from when they (accidentally) gassed their own fish. 

If you don't have any fish you could ramp the CO2 right up, somebody will be able to tell you how high you can go, but for terrestrial plants with abundant PAR you can get up into the thousands, with about 1000ppm giving maximum efficiency for Tomato, and even for humans you need to get to about 40,000 ppm CO2 (4%) to cause rapid death. 

cheers Darrel


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## CeeJay (9 Jun 2011)

Hi all


			
				hotweldfire said:
			
		

> Anyway, if I can encourage an interesting debate then I'm a happy chappy.


So you should be, you've got all the 'big guns' involved in this one   

Thanks for the link Clive, I missed this when it was originally posted   


			
				ceg4048 said:
			
		

> We have to remember that the adaptability of the plants is also a key factor in the dynamic of BBA. Not all plants have the same adaptability and not all have the same efficiency of uptake. This inequality also applies to individual specimens within the same species based on their current health.


Kerching! The lights have finally come on   
That explains so many events in my early tanks


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## hotweldfire (10 Jun 2011)

Hi All,

Please disregard my questions about dosing ferts and CO2 - have asked these on my journal instead


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