the right amount of co2

[trong]

i want to know if i got this (finally)!!! my 80 gallons of water in the 90gallon tank has a Kh of 1. between 15 and 20 mg/L CaCo3 before lights on, with a new pair of calibrated pinpiont ph probes, one on each side of the tank ph reads 6.45 and 6.44 the tank also has a grounding probe in it. 1 hour and 15 min before lights on, co2 turns on. when lights come on ph is at 6.09 and 6.05. this tells me (if im right that i have close to 30ppm co2) as the photo period goes for its 9 hour cycle the ph drops to 5.95 and 5.89. this is OK, right? do i have this? or is co2 to high ? i remember reading something about the kh shifting slightly when lights and co2 start but i'm fuzzy on what that was.. can anybody clarify?

 

[trong]

i forgot to mention the drop checker with 4kh solution at the bottom front of tank is green always.

 

[dbazuin]

What kind of fish d you have. 5.95 is to low for most fish I know.
KH 1 is very low for adding CO2. I think 4 is the minimum.
The reading of the drop checker means nothing if the KH of the solution is 4 and your tank 1. The trick is that you get both the same.

 

[trong]

thanks for your responce dbazuin, but may i suggest you reread the intell on the drop checker and calibrated solution. as for my fish i'm sure you've heard of cardinal tetras. they come from very acidic water with low kh. as do angel fish.
thanks again for your responce

 

[Gerryd]

Trong,

Please note that a green color does not indicate sufficient c02.

1. checkers have a 1-2 hour lag in response time.
2. It is at a fixed position

So all you really know is that 1-2 hours ago the c02 may have been good.

Many folks have a yellowish color in the checker..

You really should try and move it around some to get a better idea. Using 2 is not a bad idea.

Ideally, c02 should be adjusted SLOWLY and CAREFULLY...

You have enough when the plants all grow well with NO ISSUES and you have minimal algae...

AND fish are also okay!!!!!! This is often overlooked in a blind desire to increase c02 for the plants...

Relying on a checker and ph values (no matter how accurate) will not ensure stable or sufficient c02 levels.

Hope this helps

 

[dbazuin]

My info tells me that the cardinal tetra (Paracheirodon axelrodi) can be hold in a PH range of 6.5-7
So 5.89 is to acid I think.
I personally would not risk it.

I have always been told that adding CO2 with such a low KH is very risky. The PH can suddenly drop.

Maybe there is someone here who can tell us more.

 

[hani]

same problem here, kh1-2, ph6.7 at am co2 off, i went down to ph5.4 with co2, been like that for 3-4 days, rcs still alive as my SAE and Oto.

 

[Tom Barr]

i want to know if i got this (finally)!!! my 80 gallons of water in the 90gallon tank has a Kh of 1. between 15 and 20 mg/L CaCo3 before lights on, with a new pair of calibrated pinpiont ph probes, one on each side of the tank ph reads 6.45 and 6.44 the tank also has a grounding probe in it. 1 hour and 15 min before lights on, co2 turns on. when lights come on ph is at 6.09 and 6.05. this tells me (if im right that i have close to 30ppm co2) as the photo period goes for its 9 hour cycle the ph drops to 5.95 and 5.89. this is OK, right? do i have this? or is co2 to high ? i remember reading something about the kh shifting slightly when lights and co2 start but i'm fuzzy on what that was.. can anybody clarify?

So is there anything that makes you suspicious that there's not enough CO2?
Or too much?

I have a KH of 1, no issues.

I watch the CO2 carefully, some tanks are easy, some are harder, more troublesome to get the CO2 just right.

I obviously have a lot of Cardinals:

It's tough to say what the CO2 really is or is not.
At least with the methods we have, none are that good truthfully.

I think unless there's an issue, like a Biological "test", is better for most, dial it in with the DC and the pH, then eyeball and progressively adjust slowly and in small increments.
If you have good current and moderate/low light, there's never much of an issue here.

FYI, cards........I've seen them in pH of 3.7-4.2 pH.
No KH was measured etc........

CO2 gassing from respiratory issues, not pH ......is what stresses/kills fish.

Regards,
Tom Barr

 

[Tom Barr]

BTW. Discus, full large size breeding adults and some rarer plecos are the most sensitive species as far as CO2/O2.

More so than any shrimp also.

Regards,
Tom Barr

 

[hani]

Tom, how long after the co2 turns ON will you say it takes you to hit your target Co2?

 

[trong]

my names not tom but ,it depends on surface movement and setting of bubbles per second and flow through reactor and a ton of variables

 

[shoggoth43]

I recall Tom posted a graph of one tank with the CO2 graph showing a build up of 30 - 45 minutes to reach the desired amount. It had gassed off completely within about ten minutes or so.

Your results will vary depending on delivery method and surface ripple.

-
S

Tom, how long after the co2 turns ON will you say it takes you to hit your target Co2?

 

[scottward]

There is a CO2 input rate (mainly from your CO2 delivery method + CO2 from fish + CO2 from bacterial action etc) and there is a CO2 output rate (usage by plants + degassing at surface ripple).

As the CO2 level in the water increases, I understand that it becomes progressively more difficult to add more CO2. So the level of CO2 over time is steeper at first and gradually starts to flatten out (ideally should plateu?).

I think the general consensus is that if the CO2 input kicks in 1 hour before the lights come on (which increases the CO2 output rate as the plants start photosythesising), 1 hour should be enough to take the CO2 level up to the point where it starts to plateu?

 

[csmith]

Mine comes on 2 hours prior. When the lights come on my drop checker is green. At lights off it's the lime green-ish color. It's a crude measurement, but my shrimp are still alive so I'm not overdoing it. Like shoggoth said, it all depends on what you do.