I have a ph controller, should I still turn co2 off at night?

[sherry]

my controller keeps my ph at 6.1.

at night I have an airstone.

I've always figured all that was happening by letting co2 run at night was that I was outgassing some, but that the controller kept the tank from suffering any real excess that could hurt the fish... and that maybe the fish were happier in teh consistent ph.

I have just read back 21 pages in this archive and I've seen Tom weigh in on this issue on both sides. Most often that co2 should be turned off at night, but at least once suggesting that this was not necessary with a ph controller.

So I'm asking for a tie breaker directly applicable to my situation.. If I have a ph controller, is it still better for tank and fish to turn co2 off completely at night? my co2 is in the form of mist as of this week!

Oh.. and one more quick question.. if I have kh2 naturally should I be one of those people who leave the kh alone.. or should I boost it to 3 with a 1/4 t of baking soda? I am already using gh builder.

 

[Grafalski]

Re: I have a ph controller, should I still turn co2 off at night?

I also have a ph controller and I don`t turn it off at night. It`s been like that for the last 6 months. I also keep my Ph level at 6.1 (KH 6) and my fish is OK in the morning. I tried to go lower with my Ph but at 6.0 or 5.9 fish was hiding or wasn`t eating.
Sometimes I can hear my co2 kicking in (myst) at night. It looks like I`m losing CO2 even at night (tank heavy planted) because of the surface movement.

 

[neil1973]

Re: I have a ph controller, should I still turn co2 off at night?

I also have a ph controler and run it constantly. Ph is 6.2, kh is 4 and ph drop about 1.5 which seems to be as far as i can go before the fish start to react. I have some surface movement but have still found that the min ph value wants to be determined by watching the fish in the morning before the lights are on.

 

[Tom Barr]

Re: I have a ph controller, should I still turn co2 off at night?

Most just let it run, I solve the issue by not using a pH controller.
You can turn it off at night(just the solenoid supplying the CO2, not the control unit), leave tthe the KH alone , 2 is fine if you do regular water changes(even 20% weekly etc).

Regards,
Tom Barr

 

[sherry]

Re: I have a ph controller, should I still turn co2 off at night?

I put the control unit on a timer the last couple of days, just to try to give the fish a break from the co2... (now I"m subjecting them to ph swings tho)

Kh 2 ... by leaving that alone, does that mean I am cutting back on the amount of co2 the fish get (since it takes less to drop the ph down and trip the controller)... I have controller set at 6.1/6.2 now... with kh2, should I lower that setting?

have tetras/pencils/apisto cacatoides and a couple of plecos.

I do 50 % water changes and EI (lowered dosing on po4 and no3 due to high fish load)

 

[Tom Barr]

Re: I have a ph controller, should I still turn co2 off at night?

The pH is irrelevant in this context(CO2 lowers it, not strong acids).
If you added a bunch of baking soda, that is much more serious.

KH high/low does not impact more/less CO2.

We add the same CO2 to hard as we do to soft water.
You still have the same ppm's in both cases.

Example:

See a KH 2 and a pH of 6.4
See a KH of 8 and pH of 7.0

Both have the same CO2ppm(24ppm).

If you stopped adding CO2 and waited 24-48 hours, the KH 2 and the KH 8 would have the same CO2ppm content also.

CO2 and O2 in fish respiration is a different set of issues than pH change due to buffers or strong acids.



Regards,
Tom Barr

 

[sherry]

Re: I have a ph controller, should I still turn co2 off at night?

but isn't co2 a weak acid.. and doesn't a swing of ph 6.2 to say ph 7 feel the same to the fish no matter how it is reached?


or even better.. if I eliminate all kh buffer.. my kh of 2 (or slightly less) may need to create a ph of below 6 to get 30 ppm co2.. is that okay?

 

[Tom Barr]

Re: I have a ph controller, should I still turn co2 off at night?

What happens when you do a 50-80% water change in a planted tank?

To the pH that is........
Does this hurt the fish in any way?
Do discus mine it?

Now try that same jump in pH by adding baking soda(not with your fish, but with a canary type of critter/fish, because it'll likely die)

Regards,
Tom Barr

 

[vidiots]

Re: I have a ph controller, should I still turn co2 off at night?

I am too am very new to using pressurized CO2 myself and have it on a controller which keeps it at a near constant level, it just seems to turn on less often at night.

Tom, you mentioned that the pH swing caused by CO2 wouldn't harm the fish but the same pH swing caused by baking soda would. Is this because the CO2 seems to only lower the pH and not change the KH, while from what I've read the baking soda should raise both the pH and the KH?

Just a note, I am not a chemistry geek, so too complicated of an answer might puzzle me even if helpful to others.

 

[sherry]

Re: I have a ph controller, should I still turn co2 off at night?

Tom, my kh from the tap seems to be closer to 1.5
I keep the ph at 6.0 since the ph from the tap is 6.5

If I do cut out the 1/4 t of baking soda I am using to bolster the kh, then in order to get the same amt of co2 I am getting now, my ph would end up dropping below 6.

Is that safe? I do keep SA fish.

If I try to keep ph at 6 and omit all buffering then I don't see pearling. I get pearling by using the baking soda to up the base kh/ph which allows me more co2 to bring tank down to that 6.0.