RO & CO2

[CeeJay]

Hi all

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.

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.

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? :?

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

 

[hotweldfire]

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.

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

Thanks. I finally get your Matrix reference now

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.

 

[CeeJay]

Hi hotweldfire

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

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

That made me smile

 

[hotweldfire]

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.

 

[ceg4048]

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,

 

[hotweldfire]

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.

 

[dw1305]

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

 

[CeeJay]

Hi all

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

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

 

[hotweldfire]

Hi All,

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