Can CO2 micro bubbles cause incorrect drop checker readings?

[Zeus.]

The solution I would like to see is a silicone membrane between the aquarium water and indicator solution interface, no air gap whatsoever.

Which would remove the x10,000 slower diffusion rate in air good thinking

 

[Simon Cole]

x10,000 slower diffusion rate in air

The opposite way around, faster in air. I was thinking that this would mainly block bubbles but also eliminate the phase transitions.
On a side note, does anybody use carbon dioxide titration test kits?

 

[Zeus.]

The opposite way around, faster in air. I was thinking that this would eliminate the phase transitions.

,👍

 

[xZaiox]

Once I got my Maxspect Gyres x2 and improved the tank flow/turnover I dialled back on the [CO2], which is the route I would advise if your [CO2] with 1.0pH drop isn’t doing what you had hoped

Zeus, what did you dial your CO2 back to? Do you now aim for a 1.0 drop or higher still? Did your plant growth take any hits from reducing the amount? I know you've improved the flow, but I'm curious if the plants that were previously in a good flow got effected by the reduction?

 

[Zeus.]

Zeus, what did you dial your CO2 back to? Do you now aim for a 1.0 drop or higher still? Did your plant growth take any hits from reducing the amount? I know you've improved the flow, but I'm curious if the plants that were previously in a good flow got effected by the reduction?

I cant remember how much I dialled it back but the DC was light green, I think the pH drop was reduced to about 1.3pH. With having a duel stage reg duel Solenoid/needle values and reactors it was very simple I just reduced the working pressure as counting the BPS was a little pointless.

Once I had reduced the CO2 working pressure it took 30mins to get the target pH drop I was happy with at the time, before that it took 20mins. When checked the pH wasn't stable from lights on till CO2 off so instead off reducing the CO2 injection rate on that line, I added a little timed loop on my PLC so the CO2 injection was on for say 10mins then off for 30 seconds and fine tuned the on/off loop till it was stable. Having a PLC and a duel injection setup made getting a stable [CO2] very easy compared to a normal single timer/injection setup.
The tank target [CO2] was well reduced in the Covid lockdown once my CO2 cylinders got low to very low levels as I could not get CO2. Reduced the lights and ferts at same time as well. Have since retired and moved and once moved the tank has been low tech since.

When I fitted the Gyres the plants just improved, it may of been lower [CO2] but the CO2 was delivered faster to the plants. Hygrophila pinnatifida never did well which i think was due to my very hard water.

The trouble with going for High [CO2] is when do you cut back if there's an improvement and how much do you cut back. Esp when you have a busy life at the time. It works so you continue. I would advise to always work on improving the flow once your at a lime green DC/1.0pH drop and your still having issues. Its just easier on most setups to dial the CO2 up a bit and improving the flow/turnover is harder, so we take the easy route as I did as my twin sparbar was maxed out

Plus ugly with pipework- which took 4-6hrs to clean.

My next high tech tank will be different again plan to use RO water, present house has a well so RO water will be relatively cheap compared to being on a meter where you pay per cubic meter twice once for supply the water and then for waste, which was one of the reasons I worked on the IFC remineralising sheet ( soon to be released). I do believe that remineralised RO water will enable me to achieve better results with some plants. I was never able to get Hygrophila pinnatifida to last more than 9 months with my hard water.
Think the vid below demonstrates the flow well

Getting good/great flow at substrate level in a three sided tank was the trick to the carpet which was over 50cm below water. It even had some MC in the carpet which got limited light and no elongated internodal stems the flow at the substrate level was so good.

 

[xZaiox]

Wow Zeus, what a beautiful tank, you've done a brilliant job! 😍 Excellent demonstration of good flow too - Some of my plants sway like that, but definitely not all of them. I'd like my monte carlo to grow better, and I'm assuming it's not getting enough flow being at the bottom of the tank. I had a look into that gyre pump you have, looks brilliant although quite costly.

I've just recently ordered a spray bar for my filter - I've seen Clive's posts and it seems to work for him, so thought I'd give it a go. I'm hoping they don't clog easily like I'm imagining they probably do lol.

 

[aquanoobie]

Hi @dw1305
What I am looking for is how much in ppm CO2 is going to have degassed water at atmospheric 2500 ppm CO2.

Hi all,


<"[CO2] = P/KH = 3.87 x 10-4 atm/29.41 atm M-1 = 1.32 x 10-5 M"> which gives you <"3.74 ppm CO2"> when you substitute "3.87 x 10-4" with "2.5 x 10-3".

cheers Darrel

Thank you @dw1305 very much for solving it. I was looking for this for some time and finally can see the light. So what is the result in terms of CO2 ppm at a given pH drop. We know from scientific papers and your calculations that atmospheric CO2 levels of ~400 ppm make water equilibrium of ~0.5 ppm. We also know that residential areas may have atmospheric CO2 as high as 2 500 ppm and thanks to you we now know what equilibrium this makes and that is 3.74 ppm. By having this data we can calculate tank CO2 ppm range of a typical pH drop,

1.6 pH, 19 - 150 ppm CO2
1.5 pH, 15 - 120 ppm CO2
1.4 pH, 12 - 95 ppm CO2
1.3 pH, 10 - 75 ppm CO2
1.2 pH, 8 - 60 ppm CO2
1.1 pH, 6 - 48 ppm CO2
1.0 pH, 5 - 38 ppm CO2

I don't know but these ranges, or inaccuracies, are posible and are dependent on the level of house ventilation function. Also this can explain why some people have success with 1.0 pH drop and others don't unless they go for larger drop.

 

[dw1305]

Hi all,

We also know that residential areas may have atmospheric CO2 as high as 2 500 ppm and thanks to you we now know what equilibrium this makes and that is 3.74 ppm. By having this data we can calculate tank CO2 ppm range of a typical pH drop,

I'm guessing that 600 ppm CO2 is a more realistic CO2 level for houses etc. There are <"figures for the pH of Oceans"> under various atmospheric CO2 level scenarios. It is a lot easier for sea water, because it is pretty consistent world wide and fully saturated with dKH.

cheers Darrel

 

[sparkyweasel]

I got a room CO2 monitor today. Only a cheap one so I don't know how accurate it is, but I think it will tell me the difference between a bit and lots, and whether it's increasing or stable. It also measures temperature and humidity, and those readings match those on another monitor I already have, so it may be reasonably OK.
It read 556ppm to start with. Then I sat in the room, breathing; went to 880ppm after 3 hours, flashing a yellow alert!
1205ppm after another hour and a half, orange alert!
I opened the window; dropped to 786ppm in an hour. Alert status; green.
All very interesting, and needing further thought.

EDIT; Two more hours with the window open and it's down to 527ppm.

 

[sparkyweasel]

I'm guessing that 600 ppm CO2 is a more realistic CO2 level for houses

It read 556ppm

Good guess.

 

[aquanoobie]

I got a room CO2 monitor today. Only a cheap one so I don't know how accurate it is, but I think it will tell me the difference between a bit and lots, and whether it's increasing or stable. It also measures temperature and humidity, and those readings match those on another monitor I already have, so it may be reasonably OK.
It read 556ppm to start with. Then I sat in the room, breathing; went to 880ppm after 3 hours, flashing a yellow alert!
1205ppm after another hour and a half, orange alert!
I opened the window; dropped to 786ppm in an hour. Alert status; green.
All very interesting, and needing further thought.

EDIT; Two more hours with the window open and it's down to 527ppm.

Hi @sparkyweasel
This is bombshell news in details thanks for sharing. What kind of CO2 monitor you got if I may ask.

 

[aquanoobie]

CO2 table

 

[sparkyweasel]

What kind of CO2 monitor you got if I may ask.

It's this one;
Meter
Lots of sellers have what looks to be the same one, some are a bit cheaper but slower to arrive.
In fact mine was £12.55 but they have now put it up to £12.99, - I must be an influencer.

 

[aquanoobie]

It's this one;
Meter
Lots of sellers have what looks to be the same one, some are a bit cheaper but slower to arrive.
In fact mine was £12.55 but they have now put it up to £12.99, - I must be an influencer.

Funny, I didn't know they are so inexpensive, I must be living under a rock. So, what about a homework, can you find under water one in this price range?

 

[sparkyweasel]

can you find under water one in this price range?

I wish

 

[Hanuman]

got a room CO2 monitor today. Only a cheap one so I don't know how accurate it is,

It's this one;
Meter
Lots of sellers have what looks to be the same one, some are a bit cheaper but slower to arrive.
In fact mine was £12.55 but they have now put it up to £12.99, - I must be an influencer.

Funny, I didn't know they are so inexpensive, I must be living under a rock. So, what about a homework, can you find under water one in this price range?

Be aware that those are not real CO2 detectors. They are actually extremely inaccurate and use a simple and cheap TVOC sensor which by design and specification are not meant to detect CO2 or measure in any way CO2 since they only output one signal. CO2 concentration is then extrapolated, calculated and faked through a chip. Proper CO2 detectors use what we call an NDIR CO2 sensors (nondispersive infrared sensor) which by themself are pricy. The component alone will cost ~30/40USD sometimes more depending the manufacturer. So any CO2 monitor out there retailing for less than 100/150USD or less will just be a scam and you can be warrantied that what you see on the screen of your cheap Chinese made device is no where close to the real concentration of CO2 in the air at any given time of measurement.

 

[Simon Cole]

@Hanuman So a bit like that guy who made £50 million during the Iraq wars selling £13 novelty golf ball finders as bomb detectors to security forces worldwide at £27,000 each. You've got to pity Trading Standards somewhat.

 

[Hanuman]

@Hanuman So a bit like that guy who made £50 million during the Iraq wars selling £13 novelty golf ball finders as bomb detectors to security forces worldwide at £27,000 each. You've got to pity Trading Standards somewhat.
View attachment 188407

Thailand's Royal Army did purchase those at some point. I remember the scandal. The Army even tried BSing the public into believing this wass all legit and highly technologically advanced and people were too dumb to understand. It was brushed under the carpet following the backlash.
edit: typo

 

[Hanuman]

For anyone wanting to have a proper CO2 sensor, this is the cheapest I've found. It's a DIY kit that will require some soldering and a bit of coding skills, but nothing too extreme.

The AirGradient DIY Kits

When we started to give away the AirGradient PCBs and only charged shipping costs, we got a lot of requests from builders about complete kits.

www.airgradient.com

There are other CO2 DIY projects out there but you need to source the component yourself and the monitor will end up costing more. For example:

https://www.the-diy-life.com/all-in...ality Monitor With CO2 Sensor - The DIY Life/

OR

You can go and buy a commercial CO2 sensor for the modicum price of 229USD 🙂

Airthings Wave Plus | Smart radon and indoor air quality monitor

Smart, battery operated, indoor air quality monitor with 6 sensors: radon, CO2, humidity, temp, airborne chemicals (VOCs) and pressure.

www.airthings.com

You will probably find cheaper ones but nothing that is genuinely a CO2 sensor for sub 100USD

 

[aquanoobie]

Proper CO2 detectors use what we call an NDIR CO2 sensors (nondispersive infrared sensor) which by themself are pricy.

Hi @Hanuman
Would this product qualify?
It says, "With 2 different sensors: NDIR and TVOC provide 2 options for you, you can choose based on your requirement." And it costs CAD $36.

Amazon product

It looks identical to what @sparkyweasel has.

3 IN 1 Portable LCD CO2 Meter Air Quality Carbon Dioxide Detector Tester Monitor | eBay