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Matnez

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9 Jan 2013
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Hello, I’m new to the world of co2 injection and I’m looking for some advice regarding my co2 levels.

I have a small 30l cube aquarium and I’m running a nano regulator from co2 supermarket.

In the attached picture is my current ph profile.

My co2 comes on at 10.00 my lights start to ramp up at 12.00 and are at full power (80%) by 13.00.

Co2 goes off at 18.30 and then lights start to ramp down at 19.00 and are off at 20.00.

I’m reaching a steady drop of 6.36 by 16.00.

To reach this drop sooner is it just a case of increasing my co2 rate? By doing this is there a risk my ph could drop lower than 6.36?

Thanks


09.00 7.14
10.00 7.14
11.00 6.83
12.00 6.60
13.00 6.53
14.00 6.44
15.00 6.41
16.00 6.36
17.00 6.36
18.00 6.36
19.00 6.44
20.00 6.55
 

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Zeus.

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To reach this drop sooner is it just a case of increasing my co2 rate?

Classic mistake, made by many

By doing this is there a risk my ph could drop lower than 6.36?

Yes, a higher injection rate will change the peak pH/[CO2]

Lowest pH by lights on ( a little drop is acceptable), then the time it takes is the time it takes

The lights coming on will cause a net shift in the pH/[CO2], I would have the lights on 1hr sooner and redo pH profile.

I would have CO2 off sooner
What I mean is that if you are struggling with CO2 stability, or are having difficulty keeping high concentrations, then it's best to focus efforts on the first half of the photoperiod and not worry so much about the second half. If you are running very strong lighting then you are really pushing the plants and it's necessary to have the CO2 going. After 4 hours, if you turn the gas off, the water stays saturated for a couple of hours after the valve closes and the concentration trails off. So if you have an 8 hour photoperiod and you turn the gas on 2 hours before lights on, you can turn the gas off after 6 hours. So the gas is still running for 8 hours but it's on-off cycle is offset by the amount of time you turn it on prior to lights on.

There is no need to run the gas for 10 hours therefore.

Plants don't really run their photosynthetic machinery for the full day anyway. Under normal conditions, after 4 hours or so they start to shut down, so that's why CO2 isn't really needed for the full photoperiod.

Long photoperiods benefit algae more than they do plants, especially if it is high intensity.
The long photoperiod is more or less for our enjoyment.

Hope this makes sense!
 

Matnez

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9 Jan 2013
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Thanks for the reply.
So what is the benefit in my case of turning the light on 1 hour earlier?

Also if I’m having them on 1 hour earlier should I be turning them off a hour earlier as well so I have the same photo period?
 

ceg4048

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To reach this drop sooner is it just a case of increasing my co2 rate? By doing this is there a risk my ph could drop lower than 6.36?
The goal is a 1 pH unit depression by lights on and If your starting pH is 7.1 then your target pH should be 6.1 and that 6.1 should happen at lights ON. The trick is to have an injection rate high enough, and to start the injection early enough to achieve 6.1 by lights on and to not have the pH driven much lower than 6.1. Keep it at 6.1 (or thereabouts) for 4-5 hours and then turn the gas off.

Any injection rate can only saturate the water with CO2 to a certain extent. The saturation means that the amount of gas being dissolved is only fast enough to compensate for the amount of gas coming out of solution and escaping the tank in addition to the amount of gas being consumed by the plants. So we're hoping to maximize the saturation, i.e., "bottom out" the pH and keep it there by the time the lights turn on. After 4-5 hours the plants start to reduce their consumption, so the gas can be shut of and the residual dissolved gas will suffice until the next morning.

Cheers,
 

JanisF

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4 Apr 2021
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Southampton, Hampshire, UK
Good morning
I don't want to hijack the topic but reading this I got curious, and that's probably due to lack of knowledge.
Correct me if I'm wrong but reading above seems like rather large pH swings throughout the day, every day. How is this not affecting the animals - fish, snails, shrimp?

Also, if KH would be high enough, let's say 8, would I still see swings in pH when adding CO2?
 

Matnez

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9 Jan 2013
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55
The goal is a 1 pH unit depression by lights on and If your starting pH is 7.1 then your target pH should be 6.1 and that 6.1 should happen at lights ON. The trick is to have an injection rate high enough, and to start the injection early enough to achieve 6.1 by lights on and to not have the pH driven much lower than 6.1. Keep it at 6.1 (or thereabouts) for 4-5 hours and then turn the gas off.

Any injection rate can only saturate the water with CO2 to a certain extent. The saturation means that the amount of gas being dissolved is only fast enough to compensate for the amount of gas coming out of solution and escaping the tank in addition to the amount of gas being consumed by the plants. So we're hoping to maximize the saturation, i.e., "bottom out" the pH and keep it there by the time the lights turn on. After 4-5 hours the plants start to reduce their consumption, so the gas can be shut of and the residual dissolved gas will suffice until the next morning.

Cheers,
Thank you for your detailed response. I have up'ed my co2 injection rate today but I'm still a long way off that 1ph drop by the time the lights are on, so I will keep gradually adjusting as the days go on.

As my lights ramp up over the period of an hour should I be aiming for that 1ph drop when they start to ramp up or when they have reached their maximum brightness?
 

Matnez

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Thread starter
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9 Jan 2013
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Good morning
I don't want to hijack the topic but reading this I got curious, and that's probably due to lack of knowledge.
Correct me if I'm wrong but reading above seems like rather large pH swings throughout the day, every day. How is this not affecting the animals - fish, snails, shrimp?

Also, if KH would be high enough, let's say 8, would I still see swings in pH when adding CO2?
I don't know enough about it all yet as I'm still learning but from my understanding the 1ph drop that we are trying to achieve is tolerated by a lot of fish. Some sensitive shrimp apparently don't do well with it but I have read that people keep red cherry shrimp in co2 injected tanks with no issue.

Mine is only a small 30L tank and I have a few amano shrimp, guppies, oto's and a nerite snail and so far the are all happy. But as you have probably read I'm not where I need to be with my co2 levels yet so time will tell.
 

Nick potts

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25 Sep 2014
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Torbay
Thank you for your detailed response. I have up'ed my co2 injection rate today but I'm still a long way off that 1ph drop by the time the lights are on, so I will keep gradually adjusting as the days go on.

As my lights ramp up over the period of an hour should I be aiming for that 1ph drop when they start to ramp up or when they have reached their maximum brightness?
I would aim for the 1ph drop by lights on.

As well as increasing the rate of injection, it might be a good idea to have your co2 come on earlier, try and hour earlier and go from there.
 

Nick potts

Member
Joined
25 Sep 2014
Messages
560
Location
Torbay
Good morning
I don't want to hijack the topic but reading this I got curious, and that's probably due to lack of knowledge.
Correct me if I'm wrong but reading above seems like rather large pH swings throughout the day, every day. How is this not affecting the animals - fish, snails, shrimp?

Also, if KH would be high enough, let's say 8, would I still see swings in pH when adding CO2?
Most fish etc are fine with the PH drop from CO2 injection, there maybe really sensitive species that don't like it but i don't know.

With a high KH you will still get a PH drop when injecting CO2
 

Matnez

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One thing I don’t fully understand is that even with the ph profile I posted above with a maximum drop of 0.78, by the time my co2 turns off my drop checker is yellow. Is this ok or is my drop checker showing my co2 levels are too high?

If I start aiming for a 1ph drop it will definitely be yellow not lime green.
 

MrClockOff

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20 Aug 2020
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Bournemouth
One thing I don’t fully understand is that even with the ph profile I posted above with a maximum drop of 0.78, by the time my co2 turns off my drop checker is yellow. Is this ok or is my drop checker showing my co2 levels are too high?

If I start aiming for a 1ph drop it will definitely be yellow not lime green.
I’ve similar issue with my drop checker once my PH drops by 1 it gets yellow. My only guess is that too many undissolved CO2 bubbles reaching the water surface inside it. I can see how CO2 mist is moving from one corner of fish tank where the diffuser is located into opposite corner where the drop checker is attached. Mist is getting inside drop checker.. so it’s pretty much useless
 

Nick potts

Member
Joined
25 Sep 2014
Messages
560
Location
Torbay
One thing I don’t fully understand is that even with the ph profile I posted above with a maximum drop of 0.78, by the time my co2 turns off my drop checker is yellow. Is this ok or is my drop checker showing my co2 levels are too high?

If I start aiming for a 1ph drop it will definitely be yellow not lime green.

I’ve similar issue with my drop checker once my PH drops by 1 it gets yellow. My only guess is that too many undissolved CO2 bubbles reaching the water surface inside it. I can see how CO2 mist is moving from one corner of fish tank where the diffuser is located into opposite corner where the drop checker is attached. Mist is getting inside drop checker.. so it’s pretty much useless

Just remember that the drop checker is just a guide (much like a PH profile).

Your fish will tell you if there is too much CO2 in the water, lethargy and gasping at the surface are signs to look out for.
 

ceg4048

Expert/Global Moderator
UKAPS Team
Joined
11 Jul 2007
Messages
9,188
Location
Chicago, USA
Good morning
I don't want to hijack the topic but reading this I got curious, and that's probably due to lack of knowledge.
Correct me if I'm wrong but reading above seems like rather large pH swings throughout the day, every day. How is this not affecting the animals - fish, snails, shrimp?

Also, if KH would be high enough, let's say 8, would I still see swings in pH when adding CO2?
Hello,
As noted above fish really do not care about pH, which is really just a calculation of the ratio of the concentration of acid ions (H+) to the concentration of the alkaline ion (-OH). Since this is a ratio, by itself the number itself does not tell us much and does not mean much until it is put into context with the agents in the tank water. I've discussed this in greater detail in the following two posts:
What is worse: permanently high CO2 or dramatic pH swing?
Whats the importance of KH ?

Cheers,
 
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