co2 noob in need of assistance.

[Shaddex]

Hey all.
Not been on forums for a few years but now back in the hobby. Hope you are all doing good.

I have a 240 litre, high lighting and planted moderately and am interested in adding pressurised co2 to it.
I have been reading and watching everything known to man about co2 but need a few questions answered that I can not find.
I have a tap pH of 6.8 but really low kh at 1-2 degrees. If I add co2 to my tank as is, am I at risk with a pH swing as do not have adequate buffering ?

Do I need to get an alkaline buffer ? Will this incress pH while co2 lowers it ?

Hope you guys can help.

 

[PheonixKingZ]

Are you sure you want a Co2 system?

There are a couple of different Co2 systems. Gas, aerosol, and yeast.

Gas and aerosol are probably the safest method, but your fish can easily die if you don’t keep the amount of output in check.

Yeast Co2 may be much cheaper, but it’s a lot more dangerous. You see, yeast ferments, creating the Co2. But each yeast and yeast setup ferment at different times and at different speeds. That means you never know when you will get a sudden burst of Co2, killing your stock.

Co2 is definitely not recommended for beginners and it takes a lot of work to get it just right.

Maybe look into some root tabs/liquid fertilizers? (Since you are just getting back into the hobby)

 

[Shaddex]

Thanks for the reply.
Had my planted tank for 18 months and looking into getting more demanding plants to grow.
Already fert dosing just not getting the growth I want. Co2 is the next step. I have all the kit (pressurised, fire extinguisher etc), I just don't 100% understand the chemistry behind a pH swing and kh buffering.
As soon as I add the co2 to my system will the pH drop as I don't have a higher enough level of kh? If so, how do I raise my kh without it affecting my pH?
Hope that makes sense.

 

[PheonixKingZ]

Yes, the pH will drop once you start diffusing the Co2. To make your water harder, crushed limestone/coral is always an option.

I would read this article: https://aquariumplants.com/getting-...r-the-kh-ph-co2-relationship-myths-and-facts/
I would read this article: https://aquariumplants.com/getting-...r-the-kh-ph-co2-relationship-myths-and-facts/

(@Wills may be able to give first hand experience, because he has a Co2 system)

 

[Shaddex]

Interesting read. Thank you.
Need to read a few times I think.

 

[StevenF]

post error

 

[Colin_T]

I have a tap pH of 6.8 but really low kh at 1-2 degrees. If I add co2 to my tank as is, am I at risk with a pH swing as do not have adequate buffering ?

Do I need to get an alkaline buffer? Will this increase pH while co2 lowers it ?

If you have a low KH, then adding carbon dioxide (CO2) will cause the pH to drop.

You will need to add a KH buffer to raise the KH up to at least 8dKH to stop the pH from dropping. The KH will need to be checked regularly because the CO2 will continue to cause the pH to drop (CO2 is acidic), and the KH will get used up as it neutralises the acid.

-------------------
PhoenixKingz idea of adding limestone, shells or dead coral rubble will help stop the pH from dropping. These items are calcium carbonate and will neutralise acids in water and stop the pH dropping. However, if you have too much acid in the water, or not enough KH buffering capacity, the pH can still drop.

 

[Shaddex]

All good replies. Thank you.
Update.
Connected pressurised co2 up today and ran it at 1bps from 1 hour prior to lights on until 1 hour before lights off.
pH dropped from 7.2 (after water change before lights on) to 6.5
My in-tank Co2 indicator stayed blue so not enough co2 in water.
Going to get crushed coral tomorrow and increase co2 to 2bps.

 

[Colin_T]

If 1 bubble per second is dropping the pH from 7.2 to 6.5, you don't want it at 2 bps. You can't drop the pH that much that quickly or you will kill the fish. Get your KH up with buffers and dead coral rubble first, then see how the pH goes with 1bps. If it's ok for a week, then increase it to 2bps.

Don't add CO2 until the light has come on. Plants take an hour or so to wake up and circulate fluids through their system. They don't take up many nutrients (including CO2) during this first hour, so having the CO2 come on an hour before lights on, is not necessary.

 

[Shaddex]

Update:

Got some ntlabs kh buffer and now tank sits at 7.4 pH and 3 dkh before co2 and lights on.
According to the kh/pH table, I need to hit 6.5ph to get optimal co2.
Running at 2bps the pH does drop to 6.5 but only after leaving co2 on for 6 hours, an hour prior to it turning off.

So, do I increase co2 to get to 6.5ph quicker or add more kh up buffer ?
Any and all advise welcome.

 

[Colin_T]

add more KH to stop the pH dropping.

CO2 works in water with any pH so I have no idea why someone is suggesting a pH of 6.5

 

[Shaddex]

CO2/pH/KH table

Please ignore the recommended ranges for good/Bad CO2 ppm, they vary by tank and lighting and other factors, a good range to target initially is 30-40 ppm. Then adjust slowly watching plant health and vigor.

barrreport.com

That table. Seen a lot of reputable YouTubers refering to it.

Also, adding more buffer, will that increase my base line pH ? It's at 7.4ish at the moment.

 

[Colin_T]

I don't know where Tom Barr got the data from for his chart and don't understand how the CO2 is meant to increase as the pH decreases so I won't comment on that.

Depending on what fish are in the tank will determine what the pH can be. If you have fish that come from soft acid water, then having a low pH will be fine. If you have fish from water with a pH above 7.0, then they will probably struggle with acid water. All fish will struggle with fluctuating pH levels.

Some KH buffers will raise the pH but others shouldn't. It depends on what the ingredients are. Sodium Bicarbonate will raise the KH and if you add enough, the pH can hit 9.0 or higher. Calcium Carbonate is not meant to raise the pH as much but still does.

What plants do you have in the tank?
Are they fast growing plants or slow growing plants?

 

[Shaddex]

I have a mixture of tropica fast and slow growers.

After reading another million posts on the net, it would seem that a pH drop of 1 before lights on is the goal.
So from 7.4ish to 6.4ish. looks like I need more injection to achieve.
Just need to keep an eye on fish and drop checker.

 

[Colin_T]

Do the websites that suggest the pH drop have plant only tanks or do they have fish in the tank?

I can't agree with dropping the pH by 1.0 point each day. I have to say that any major pH fluctuations is going to be bad for the fish. If you want to change the pH each day, that is up to you but fish never evolved to tolerate major pH fluctuation, especially if it happens every day.

If you drop the pH and keep it on 6.4 continuously, that is not an issue but having it go up and down isn't good for the fish.