Co2 And Ph

[Futralistic]

When you start injecting CO2 in a tank how much of a change in PH should be expected?

I just started injecting CO2 in my 55g tank yesterday with a 2-2 litre DIY setup (I plan on getting a pressurized system later). Over the course of the day (about 10-12 hours) my PH dropped 1.0, from around 7.6 to 6.6. I cut the CO2 off when I turned the lights off, and when I woke up this morning my PH was back up to around 7.6 again.

Is this normal or am I doing something wrong?

 

[RadaR]

How much your pH will change really depends on the KH. A higher KH and the pH wont shift much. A lower KH and the pH will fluctuate a bit. It seems as though you have a low KH. It's normal I wouldn't worry too much.

 

[Futralistic]

Thank you

 

[George Farmer]

A pH drop of one equates to approx. 30ppm CO2, no matter the KH.

 

[ShoC]

Good that will bring my 8.2ph down

 

[Futralistic]

I read somewhere that you are supposed to turn off your CO2 at night because CO2 levels will go up due to lack of photosynthesis with the plants.

Ive also read that it is ok to keep it on because fish in the wild are used to the PH fluctuations and higher CO2 levels at night.

Whats the truth?

BTW I have been turning my off at night.

 

[George Farmer]

You can keep it on at night providing there's enough oxygen. It's generally only an issue with no surface movement and/or overstocked fish.

I have my CO2 on 24/7 these day. The pH swing is lower than when turning it off at night.

My crypts seem very sensitive to pH swings, and 24/7 injection with plenty of surface movement all the time is the best method for me.

I go through more CO2 with the surface movement but it's cheap enough (£10 for 2Kg).

24/7 CO2 is more practical with yeast CO2 too.

 

[reggieschuey]

You can keep it on at night providing there's enough oxygen. It's generally only an issue with no surface movement and/or overstocked fish.

I have my CO2 on 24/7 these day. The pH swing is lower than when turning it off at night.

My crypts seem very sensitive to pH swings, and 24/7 injection with plenty of surface movement all the time is the best method for me.

I go through more CO2 with the surface movement but it's cheap enough (£10 for 2Kg).

24/7 CO2 is more practical with yeast CO2 too.

hey george just want to know whats the point of leaving it on at night as well? don't plants only need it during day time?

 

[George Farmer]

You can keep it on at night providing there's enough oxygen. It's generally only an issue with no surface movement and/or overstocked fish.

I have my CO2 on 24/7 these day. The pH swing is lower than when turning it off at night.

My crypts seem very sensitive to pH swings, and 24/7 injection with plenty of surface movement all the time is the best method for me.

I go through more CO2 with the surface movement but it's cheap enough (£10 for 2Kg).

24/7 CO2 is more practical with yeast CO2 too.

hey george just want to know whats the point of leaving it on at night as well? don't plants only need it during day time?

Yes, the vast majority of plants only need CO2 during lighting.

I inject it 24/7 as it keeps the pH more stable - that my crypts seem to prefer. I used to use a solenoid but suffered from melting leaves. When I switched to 24/7 they stopped. Could be coincidence though. I may try going back to solenoid just to see.

Using my drop checker filled with 4dKH reference solution I can see that CO2 is stable at 30ppm too, even at night. This is because I have a fair bit of surface agitation, to ensure CO2 doesn't build up to excess.

Another benefit to 24/7 injection is the CO2 is as good level as the lights come on. Those using solenoids can also achieve this by having the CO2 come on an hour or so before lighting.