Clay Pellets and CO2 Problems

[Neilix]

Recently finished building a Paludarium that a managed to seed and obtain a good covering of Glossostigma on the floor. All looked good until I filled with water, and within two days it all started to die. After doing some research I came to the conclusion that there wasn't enough CO2 in the water. This was confirmed when I tested the water and found the levels were less than 3%. Much less than the 20% that there should be.

I than added a CO2 system in an attempt to bring the levels up, but nothing happened. I tried adding carbonated spring water to boast the levels. Which worked well, but within 24 hours they had dropped again to below 3%. This trick has now been repeated 4 times, but the spike in CO2 never lasts.

I did some further research, and I now believe the problem is the clay pallets, that I used to infill the areas under the land. It seems that clay pallets are very efficient at removing and storing CO2 from water. Unfortunately for me, these clay pallets probably account for about 1/5 of the volume of water, so the amount of CO2 they can extract is far beyond what I could have imagined.

I am still hoping that at some point the clay pellets must reach a saturation level, and will stop absorbing all the CO2 that is being added. But this for me is a complete unknown.

Has anybody else had a similar experience or knows more about the clay pallets in aquariums.

I have even started adding liquid CO2, in the hope that this will help. Although this doesn't seem to register on the CO2 monitor. But that could be due to the fact that its a chemical substitution for CO2 and the monitor may not pick it up.

 

[jameson_uk]

Recently finished building a Paludarium that a managed to seed and obtain a good covering of Glossostigma on the floor. All looked good until I filled with water, and within two days it all started to die. After doing some research I came to the conclusion that there wasn't enough CO2 in the water. This was confirmed when I tested the water and found the levels were less than 3%. Much less than the 20% that there should be.

Not sure where these percentages come from? IIRC water will generally end up at about 3 or 4 ppm CO2. If you want it higher then you need to add it. Are you sure your plant is actually aquatic? A lot of seed plants are not actually aquatic and will die as soon as they get wet.

I than added a CO2 system in an attempt to bring the levels up, but nothing happened. I tried adding carbonated spring water to boast the levels. Which worked well, but within 24 hours they had dropped again to below 3%. This trick has now been repeated 4 times, but the spike in CO2 never lasts.

What type of system? CO2 is going to get used up but will also gas off due to surface agitation

Has anybody else had a similar experience or knows more about the clay pallets in aquariums.

I doubt clay will hold onto CO2. I am sure some of the scientists can confirm. It is much more likely it has been used up, gassed off or was never there to start with.

I have even started adding liquid CO2, in the hope that this will help. Although this doesn't seem to register on the CO2 monitor. But that could be due to the fact that its a chemical substitution for CO2 and the monitor may not pick it up.

Liquid carbon is not CO2. Have a search here for glut and you will see plenty of discussion of what it is and how it works.

 

[Neilix]

Thought I should share an image. All the clay pallets are under the central land mass, across the back, and behind the waterfall. Unfortunately, 90% of the Glossostigma carpet has gone.

I am confident, if I can get the CO2 levels up, it will recover.

 

[Neilix]

CO2 levels comes from the indicator I have placed in the water. My mistake before I actually should have written 20mg/l. The monitor indicates anything below this is not enough.

As for the seeds. Around 10% still remain, and no more seem to be dying. So I am fairly confident the seeds are genuine glossostigma.

CO2 system. https://www.petsathome.com/shop/en/pets/tropica-plant-growth-system-60 nothing special, I was just I was in a hurry to try something, and got the first thing I could get my hands on.

The clay theory I have, came from research I read about carbon capture. It appears they are using clay pellets to capture CO2. Which can then be released when heated to high temperatures.

I appropriate liquid carbon is not the same as CO2. That's why I suspect adding this doesn't register on the monitor inside the tank. Hopefully, the remaining regions of carpet are getting some help and will recover once I can get the CO2 levels to remain stable.

 

[dw1305]

Hi all,
It looks good, but I'd probably go for a different carpet. I like moss, it is nice and low maintenance.

This was confirmed when I tested the water and found the levels were less than 3(ppm) Much less than the 20(ppm) that there should be.

Like at @jameson_uk says it is really difficult to measure dissolved gases in water.

Because of this difficulty people who add CO2 use a solution of known hardness (4dKH solution) and a specific pH indicator (bromothymol blue) <"in a drop checker"> to make use of the carbonate ~ CO2 ~ pH equilibrium and the experimentally derived pH ~ CO2 relationship.

The chart (below) only works when you add CO2.

If you don't add CO2 the amount of CO2 in the water is dependent on the amount of CO2 in the atmosphere and the temperature. At 20oC, and 400 ppm atmospheric CO2, you get somewhere around 1ppm dissolved CO2.

So I am fairly confident the seeds are genuine glossostigma.

We have a <"few threads on this">.

cheers Darrel

 

[dw1305]

Hi all,

The clay theory I have, came from research I read about carbon capture. It appears they are using clay pellets to capture CO2. Which can then be released when heated to high temperatures.

True, but you don't need to worry about it happening with your clay pellets.

<"Scientists"> are looking at using expanding (2:1 smectite) clays to capture gaseous CO2 from low temperature industrial processes. These are the sort of clay used in drilling mud, expanding cat litter etc. We've just had "bentonite" injected into the <"lake dam on campus">.

I assume that your pellets are a fired clay, like <"Hydroleca" or similar">, and I've used them a lot in trickle filters etc. and they are good stuff.

The actual process of CO2 capture is similar to the "Ion Exchange" process that occurs with ions in solution and <"active substrates">. You lose a lot of the CEC of a clay when it is fired, as well as its ability to expand and contract.

cheers Darrel

 

[Neilix]

Interesting.. well if it's not the clay pallets, then there is something else causing the co2 levels to crash. I just done a dip test just now, and I have pH7 and KH40. I notice the chart you posted only goes to 20 for KH°. So I am hoping there is difference between KH and KH°

 

[dw1305]

Hi all,

well if it's not the clay pallets, then there is something else causing the co2 levels to crash.

The CO2 hasn't crashed. Any CO2 you add will equilibrate with atmospheric levels, you have to keep adding it if you want to achieve more than 2 or 3 ppm CO2. Have a look at the <"Bouncy Castle"> analogy.

Liquids can potentially hold a lot of CO2 (think of a can of coke), but that excess CO2 will eventually all escape into the atmosphere. Once the excess CO2 has escaped your coke is then both flat and strange tasting because it has lost the bubbles and the acid component (the additional dissolved CO2).

You can use a drop checker to estimate CO2 level, but you can't directly measure CO2 in your water, unless you use a very expensive dissolved gas meter (or you are good at maths and have a <"CO2 coulometer">. All the methods of estimating CO2 are titrimetric and rely on an acid/base titration with a base (a H+ ion acceptor) of known alkalinity, using the assumption that the acid (H+ ion donor) in the water comes from the small proportion of CO2 that dissolves as carbonic acid (H2CO3 ~ dissolved as H+ and HCO3-). This assumption isn't always (often?) true.

If you aren't adding CO2 you always have the same amount of total inorganic carbon (TIC), but occurs in three states. The graph below shows the TIC/pH curves for water and atmospheric levels of CO2 (From <"https://www.ukaps.org/forum/threads/reconstituters.55797/page-2">).

I just done a dip test just now, and I have pH7 and KH40. I notice the chart you posted only goes to 20 for KH°. So I am hoping there is difference between KH and KH°

They are both dKH (the "°" and "d" both abbreviate "degrees"). The chart only goes up to dKH 20 because water is fully saturated with carbonates at about 18 dKH, when you have calcium present. You can <"get higher values in solutions"> (using a salt like sodium bicarbonate (NaHCO3)), but as soon as you have any calcium ions (Ca++) present then the dKH will stabilise as lime scale (CaCO3) is precipitated.

The definition, and derivation, of the various hardness measurements are in this thread <"the Krib: Hardness>. Also you didn't actually have dKH 40 and/or pH7, these figures are an artifact of the way the kit works, not the content of the water.

cheers Darrel

 

[Neilix]

Thank you for that, really helpful. So its obvious the co2 system I am using it not capable of getting the levels up to around 15-20ppm. I guess I will have to invest in a better kit.Back to the researching google....

 

[ian_m]

CO2 system. https://www.petsathome.com/shop/en/pets/tropica-plant-growth-system-60 nothing special, I was just I was in a hurry to try something, and got the first thing I could get my hands on.

So its obvious the co2 system I am using it not capable of getting the levels up to around 15-20ppm

Looks like it. The Tropica system looks an excellent way to move your wallet contents to the retailer without have to worry about gassing any fish in the process.

Decent regulators and injectors from either of these two suppliers.
https://www.co2art.eu/

https://www.co2supermarket.co.uk/

I have a single stage dual gauge regulator from the 2nd link, bought in 2012 and works fine on a fire extinguisher along with an inline diffuser. Easy peasy to reach 30pmm (or more).

Whoops...

 

[dw1305]

Hi all,

Back to the researching google....

Search on this forum. I'm personally not a CO2 user, but we have plenty of <"practical expertise">.

cheers Darrel

 

[sparkyweasel]

Agreed, there are lots of people on here who really know their stuff, plus they're not trying to sell you anything.
There's lots of misinformation, outdated ideas, and bad 'science' on the net. On this forum you get steered in the right direction, lots of practical experience, and backed up with real science if you want to look into the theories behind it.
Not blowing my own trumpet here, because, like Darrel above, I don't inject CO2 either, but the guys who do so will put you right.

 

[Simon Cole]

Hi Neilix,
You've got some great advise above. I would like to trow a few ideas into the pot. The first would be to review whether you have enough lighting because your paludarium is quite tall. Wickes do some neat 30W slimline LED floodlights for about £12 that could help to get things going. I am a CO2 user and I've got three systems running. The simplest is second-hand fire extinguisher and welding regulator, which was sensitive and didn't need a needle valve. It cost about £30 to make. I've also got a top range CO2 Art system. When I started dabbling with CO2 I gradually changed systems from the one that you had, to yeast based, single use cylinders, glut, right up to what I use today, which includes reactors. I wish I had the right advise to start with - but this forum has been a fantastic place to get help and learn.