• You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up

Having difficulty hitting the right CO2 concentration

corymbosa

New Member
Joined
2 Feb 2022
Messages
22
Location
Singapore
Hi guys! It's my first time doing a high-tech tank and I need some advice regarding the adequate CO2 concentration for my setup (1 week old). Livestock has not been added to the tank yet.

IMG_0109.JPG

Hardware:
Tank: 90x30x30cm (81L)
Effective water volume: ~60L
Hardscape: Spider wood, seiryu rocks, tropica aquasoil in filter bags capped with ADA sand
Lighting: Week Aqua P900 at 30% intensity for 8 hours a day
CO2: Too many bubbles to count, but it gets turned on 1 hour before the lights go up and stops one hour before lights retire
Filtration: Oase biomaster 350


Plants:
Background:
Pogostemon erectus
Rotala macrandra
Alternanthera reineckii ‘Rosanervig’
Rotala green

Midground:
Anubias nana
Anubias barteri
Anubias nana ‘golden’
Eriocaulon sp Vietnam
Bucephalandra ‘green broad leaf’
Bucephalandra ‘velvet’
Bucephalandra ‘kadagang’
Cryptocoryne lutea ‘hobbit’
Cryptocoryne balansae
Echinodorus ‘reni’
Staurogyne repens
Hygrophila pinnatifida
Hygrophila polysperma ‘rosanervig’
Hydrocotyle tripartita

Foreground:
Marsilea crenata

Water parameters:
I'm using a cheap pH meter and API test kit to test for pH.

Aerated tank water (bubbled overnight)
pH (meter): 8.33
pH (API): LR7.6, HR8.4
GH: 8
KH: 8


Fresh tank water before CO2 injection
pH (meter): 7.67
pH (API): LR7.2, HR7.4
GH: 8
KH: 3


CO2 injection pH stats
CO2 gets turned on 1 hour before lights go up. So at the 1 hour reading, that's when the lights just start.

1 hour: 6.6 (API), 6.84 (Meter)
2 hours: 6.4 (API), 6.64 (Meter)

Will be updated~


Optimal CO2 concentration based on pH drop
What I understand is that the optimal CO2 concentration is achieved with a pH drop of 1. But which starting pH should I be looking at? Fresh tank water or aerated tank water?

What should be the pH my tank water should stabilize at during CO2 injection hours?
 
Last edited:
I use a drop checker rather than profiling because I run a low tech with added CO2. I do understand that profiling is the best way to go for high tech though. From the figures you’ve given you do seem to be adding too much, maybe others with experience of profiling can offer different advice but I’d say dial it back a bit and aim for the 1ph drop. Of course if you don’t intend to add livestock then I believe it’s less important and you can go with a bigger drop. If you are going to add fish or shrimp then in my experience its safer to add them before the CO2 switches on (or even better, turn the CO2 off on the day you introduce them) to give them a better chance to acclimatise.
Hope this helps, good luck 👍
 
With a nearly 2ph drop, that would indicate that ur pumping a metric ton of Co2 in there and/or your surface agitation is low. 😂

I like to use a two pronged approach and always have a Co2 drop checker in place as this gives a quick easy to read ‘condition’ report as such. Right now yours would be very very yellow.

If you intend to add livestock at any point, I would start dialling back now and aim for that 1ph stable drop and maybe get a drop checker as a back up to give you some extra comfort. Some scapers will run at higher than 1ph and with a drop checker at lime green to yellow but you need a bit of experience with the system and with recognising fish stress signals etc to do this well, so if you are new to the Co2 game, I would definitely be going for a green drop checker and no more than 1ph drop.

Make sure you have your Co2 within those reasonable parameters before any livestock are added as ideally you don’t want to be experimenting and tweaking quite so much once they are in. Minor adjustments are fine and often necessary as the tank grows in but you want to get the big stuff out of the way.
 
With a nearly 2ph drop, that would indicate that ur pumping a metric ton of Co2 in there and/or your surface agitation is low. 😂

I like to use a two pronged approach and always have a Co2 drop checker in place as this gives a quick easy to read ‘condition’ report as such. Right now yours would be very very yellow.

If you intend to add livestock at any point, I would start dialling back now and aim for that 1ph stable drop and maybe get a drop checker as a back up to give you some extra comfort. Some scapers will run at higher than 1ph and with a drop checker at lime green to yellow but you need a bit of experience with the system and with recognising fish stress signals etc to do this well, so if you are new to the Co2 game, I would definitely be going for a green drop checker and no more than 1ph drop.

Make sure you have your Co2 within those reasonable parameters before any livestock are added as ideally you don’t want to be experimenting and tweaking quite so much once they are in. Minor adjustments are fine and often necessary as the tank grows in but you want to get the big stuff out of the way.
I managed to lower the co2 injection rate to around 3 bubble per second and here are my pH readings (de-gassed water pH is 8.33 (meter) and 8.2 (API):
1 hour - 7.24 (meter), 6.6 (API)
2 hours - 7.1 (meter), 6.6 (API)
3 hours - 6.97 (meter), 6.4 (API)
4 hours - 6.95 (Meter), 6.4 (API)

Its interesting that both meter and API readings agree with each other at higher pH (>8), but at lower pH they don't.
 
Back
Top