CO2 measurements dont add up!? - The Planted Tank Forum
 
LinkBack Thread Tools Display Modes
post #1 of 7 (permalink) Old 03-14-2006, 09:49 PM Thread Starter
jkc
Guest
 
PTrader: (0/0%)
Join Date: Dec 2005
Posts: 3
CO2 measurements dont add up!?

Hi All,

Ive done a lot of reading on this forum & there seems to be a wealth of knowledge so im hoping you can help.

I currently have a 48hx20wx28h planted tank with discus & corys & dither fish.

I currently dont inject CO2 but I now have a pressurized system that I would like to set up (eventually, when I get things sorted).

Over a little while now I have been bringing the water parameters up a bit as my PH was 6.6 & KH 30 mg/l (ppm). I wanted to get the KH to somewhere over 5

The readings I took yesterday PH 7, KH 90 mg/l (ppm).

I was running an airstone simply because if I didnt the discus seemed to be gasping for air.

Today I turned the airstone off durring the day as I was at home all day. The fish were fine up until this evening when they started gasping again. I took some readings PH 6.8 KH 70 mg/l (ppm). Now using Chucks CO2 calculator that gives me 33ppm CO2. Im not injecting so whats going on??

I have been using a mix 50/50 of RO and HMA/CBR 2 carbon filtered water so I did a little experiment and left some of the CBR 2 water in a jug to stand over night. The readings I took at the start were PH 7.4 KH 150mg/l (ppm) TDS 290. After 24hrs results were PH 7.4 KH 170 mg/l (ppm) TDS 297. According to the CO2 calculator thats 20ppm CO2.

Whats going on??

Phosphate reading is currently 2.5 ppm.

Fish must be gasping for a reason right??

Any help greatly apprecated!
jkc is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 03-14-2006, 10:01 PM Thread Starter
jkc
Guest
 
PTrader: (0/0%)
Join Date: Dec 2005
Posts: 3
Just to addthe airstone has been runnig for about 20 minutes now and the fish seem to have stopped gasping!! I cant see any other reason than the CO2 being high, but im not injecting so I just dont get it!???

HELP needed!!
jkc is offline  
post #3 of 7 (permalink) Old 03-14-2006, 11:22 PM
Guest
 
PTrader: (0/0%)
Join Date: Feb 2004
Posts: 197
if you arent adding any co2 then you dont have 20ppm of co2 theres got to be some thing in your tank thats thats messing up the test are u adding any ph down???
John S is offline  
 
post #4 of 7 (permalink) Old 03-14-2006, 11:50 PM
Guest
 
PTrader: (0/0%)
Join Date: Feb 2006
Posts: 214
Humm!

Did you aerate your replacement water?

The CO2 in a Tank without injection should be around only between .07mg/l(ppm) to .6 mg/l (ppm), depend of surface agitation.

I think the gasping is probably due to low oxygen in the water...

—> do you have lot of water movment
—> do you have pearling of your plant
—> what type of filtration

The Chart become unusable in presence of any type of buffer, acid (peat, ph minus etc or alcali (CACO3, ph +)

You have to use Krause system to find your co2 content :

Hanns-J Krause CO2 Test
Author Handbook Aquaria Technology
Krause recommends a different method to measure CO2 content. That method is insensitive to the presence of unusual buffers.

Step 1: Take another water sample with some pH indicator and run the hose from an air pump into the sampe for a few minutes. This sets the CO2 level at 0.6ppm.
—>Measure pH of the water (=X).

Step 2: Take small water sample with some pH indicator. Stick a straw into the water and exhale through the straw into the water sample for two or three minutes. This sets the CO2 level at 60ppm.
—>Measure pH of the water (=Y)

Step 3:
The optimum CO2 concentration of 10-20ppm is at the pH value about 2/3 of the difference between X and Y:
pH,opt = X +.67*(Y-X).

As an example, if you measure pH 8 with the first sample, and pH 6.5 with the second sample, a tank pH of 7 corresponds to 30ppm CO2, regardless of any buffers that might otherwise confuse a CO2 test or distort the charted values.

PH Opti (6.995) = x(6)*(y(8)-X(6)
Glouglou is offline  
post #5 of 7 (permalink) Old 03-15-2006, 04:25 PM
Guest
 
PTrader: (0/0%)
Join Date: Feb 2006
Posts: 8
For the Hanns-J Krause method, it says take a sample.
Questions.
1) How big of a sample, can you just fill up a regular test tube?
2.) Are you supposed to add the pH first or after you add o2 or Co2?

Thanks,
wguttrid is offline  
post #6 of 7 (permalink) Old 03-18-2006, 12:03 AM
Guest
 
PTrader: (0/0%)
Join Date: Feb 2006
Posts: 214
Krause method

I use hagen ph kit, I use the normal sampling required for the test.
Yes for the regular test tube...

You add the reagent (as indicated for the test kit you use) after oxygenation and after CO2 saturation.
Glouglou is offline  
post #7 of 7 (permalink) Old 03-18-2006, 02:35 PM
Wannabe Guru
 
RoseHawke's Avatar
 
PTrader: (9/100%)
Join Date: Mar 2004
Location: Central Alabama
Posts: 1,878
Send a message via AIM to RoseHawke Send a message via MSN to RoseHawke
Just a guess, but it sounds like the problem is more lack of O2 rather than too much CO2. This is a discus tank, yes? My understanding is that water doesn't hold as much oxygen at higher temps.

Sláinte!
Cindy



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
— 2wpg CF lighting; pressurized CO2; 18 watt Turbo-twist UVS; Eheim Pro II 2028; eco-complete; 2 Pearl Gouramis; 7 Harlequin Rasboras; 3 Otocinclus catfish

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
— lo-tech; 1.8 wpg DIY CF light; no CO2; Aquaclear mini; Schultz substrate; java fern; java moss; 7 Neon Tetras; 1 flame dwarf gourami
RoseHawke is offline  
Reply

Tags
None

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the The Planted Tank Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome