Old school co2 method.

zozo

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Interesting.

What colour is your drop checker ?

You could use multiple drop checkers with indicator/solution diluted 50:50 with distilled water to read colour change at 30ppm, 15ppm and 7.5ppm ?

Haven't yet installed one.. And i have to search for it, i have only one left somewhere. Not have used any co2 for over 2 years.. Than i have to make me some fluid too.
Seeing the ph profile from previous experience it think it should be on the tipping point of green. :) I'll cook me up some dkh4 and see what it tells us.
 

zozo

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Same rate of disolvation as mine. I refill my in tank bottle from the yeast/sugar mix that has been pressurising from the previous day. Quick squeeze in the morning and I'm set for the day (check valve stopping back syphon )

Well so far the easthetic problem looks partialy solved.. Having the bottle above the surface works as good..

The results so far makes me want to experiment with a vacuum co2 chamber in the sump.. Seeing the rate it dissolves this could easily be automated to refill at the same rate it dissolves.. In the sump invironment parameters at least can be kept relative stable regarding temp swings.
 

zozo

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Impressive result, if the tank had plants in the CO2 would be used faster during photoperiod! or I would expect to be :rolleyes:

Yes it obviously would, i stripped this little tank down from a lot of plants lately and gave them away. It indeed is very sparsly planted.. Now it only contains a few plants dwarf sage, crypts and some mosses. It's my plant bin for things i don't like to dispose off... I'll drop in an extra bunch of potamogeton gayi from the garden and some bacopa. Got to much of it anyway.. :)

But as stated in the video, it seems to dissolve quicker with more demanding plants in the tank.. In how far it equals out the numbers i have no idea..
 

zozo

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:) did put some more consumers in it.. Later on i will put in the drop checker.. For now it stabelized steadily at pH 7.7 in this natural rather low light cycle.

DSC_0134.jpg
 

zozo

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Another point of concern, the bottle doesn't only releas its co2 contents to the water, the water also degasses back into the bottle. As shown in the pictures above it doesn't empty completely after 24 hours about 1/4 of the bottle is still filled with gas. Than you if refill it from bellow, but it aint only co2 what's left in there. It possibly is part co2 and part oxygen etc. the water degasses back into the bottle. Thus refilling it with this so called poluted co2 bubble left in the bottle you put less co2 back.

I noticed a signicficant 0.4 less pH drop after the 3th refill.. This can only proof the above. Took the bottle out and started with a full fresh co2 refill again the pH drop was again as before.

So for optimal result you should empty old gas left in te bottle before you refill..

Best practice for this method would be installing a hose connetor to the bottles top side with a small valve. Degass it and refill it from above and not from bellow with the a bubble left in there.. :thumbup:
 

ian_m

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Another point of concern, the bottle doesn't only releas its co2 contents to the water, the water also degasses back into the bottle. As shown in the pictures above it doesn't empty completely after 24 hours about 1/4 of the bottle is still filled with gas.
Well spotted & deduced batman, as they say !!!.

I suspect you will find it will be both nitrogen and oxygen being released from the water as these are about 100 times less soluble than CO2. Next time you end up with this left over "gas" :cool: stick a burning match in it and see if it extinguishes the match, I suspect it will be nitrogen whose solubility is less than oxygen, (0.02ppm as opposed to oxygen 0.04ppm), thus will not so easily re-dissolve back in the water.
 

zozo

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Thank you ian_m.. :)

stick a burning match in it and see if it extinguishes the match,
But if you manage to get a burning match in there like this
dsc_0131-jpg.jpg

You're probably going to make David Coperfield feel very invious..

btw this pic was after the first night over.. Noticed the left over bubble getting bigger the 2nd night over after that.. :)
 

zozo

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The Tropica version of this says it needs to be vented once a week, which I guess is to resolve that issue: https://tropica.com/en/plant-care/co2/system-60/

Once a week? seems a bit long to what i experienced. Seen the pH drop from 8.3 to 7.6 and after the 3th refill it stopped dropping at 8.0. Relatively a drastic reduction quite soon. I would rather say vent it daily or at least once every 2 days.

Or monitor it and decide from there when it's necessary..
 

Zeus.

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Trouble with having the bottle above the water is there will be a negative pressure once the water rises above the level of the water in the tank so it may be hard to get all the CO2 to dissolve. If/when the bottle is emersed in water completely the pressure of the CO2 in the bottle will be higher so it should dissolve better - well thats my thoughts on it ;)
 

Marc Davis

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Trouble with having the bottle above the water is there will be a negative pressure once the water rises above the level of the water in the tank so it may be hard to get all the CO2 to dissolve. If/when the bottle is emersed in water completely the pressure of the CO2 in the bottle will be higher so it should dissolve better - well thats my thoughts on it ;)

your typical drinking bottle is going to stand out in the water, yes. But the tropica "box" is really quite discreet. Especially if the tank is heavily planted. Im going to buy the system later i think just for the box. Once the co2 spray can has run out, ill just attach my yeast/sugar bottles to it.
 

zozo

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I saw the colombo version in the LFS also very discrete little container. Smaller then 500cc it looks like a 250cc to me, but didn't check . Tho i might also effectively only fill 400cc in a cut pet bottle.. I bought the colombo refill can..

But seeing the pH profile, it is remarkably stable during the intire light cycle.. If refilled every morning and the bottle slowly empties the co2 and refills with water. By the time it reaches the point it reduces the pH the light cycle is over. Next morning when it needs a refill pH is back at 8. From that perspective it kinda works a charme, having an almost 1 unit drop.. Since it is in my case from a rather high over pH8 starting point it aint enough to make the dropchecker react very much it stays in the blue range. But for a small low energy tank i guess it's a decent helping hand.

I'll give it a try with the bottle submersed and see if the water gasses out less into the bottle. Not going to make predictions, was far off with the first one too, this time i look before i leap.. ;)

But a vent is necessary anyway.. I don't see much waste venting it every 2 days to have the optimum out of it. It is a darn waste with using the spray cans, that's a complete rip off, no fun with almost € 1 for 1 gram of Co2.
 

zozo

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Trouble with having the bottle above the water is there will be a negative pressure once the water rises above the level of the water in the tank so it may be hard to get all the CO2 to dissolve. If/when the bottle is emersed in water completely the pressure of the CO2 in the bottle will be higher so it should dissolve better - well thats my thoughts on it ;)

Reading back on @Marc Davis reply and his 500cc submersed coke bottle empties in about the same time span.. Than i doubt there will be a huge difference.. Anyway the pressure on the surface is 1 atmosphere, so the updraft pressure in the vacuum bottle on the co2 is the same. Since 1 atmosphere is 10 metre water column, it is easy to calculate the extra pressure if 12 cm submersed.. So each cm depth is 1/10000 bar extra..
 

Edvet

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Anyway the pressure on the surface is 1 atmosphere
So submerging the bottle will increase pressure , not as much as a diver going to the Mariana trench, bit there will be an increase:)
 

zozo

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I was more aiming my arrows on this, since i live close to the border i have a German delivery address, no international shipping cost as local a pic up. :)
https://www.ebay.de/itm/Kohlensaure...910803?hash=item56b2338ed3:g:468AAOSwX0xbPEIq

So submerging the bottle will increase pressure , not as much as a diver going to the Mariana trench, bit there will be an increase:)

Probably, i'm not into the mater enough to say something conclusive about it.. As said each 10mm down is a 0.0001 bar pressure buld up. If you can speak of a pressure increas, relatively.. I have no idea on the numbers of the force needed for co2 compresion as in boyls law. There obviously will be a form of counter pressure by the gas. I would need to dig realy hard for numbers and formulas. To calculate which force is the greatest.

For now obviously the upwards pressure on the co2 in the vacum is 1 atmosphere. If the level of co2 is 15cm bellow the surface it will be 1.0015 atmosphere.. I guess the whole only can be theoreticaly calculated without an accurate barometer measuring the invironmental air pressure which next to that never is constant. Without it we assume it is 1.. If it isn't you always will be a few 1/10000 units off.

Neglecable if you ask me.. If it wasn't we didn't use 1 as a starting point for calculation. :) And an atmosphere pressure sensor would be common tool as must have.
 
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