co2 affecting fish?

[bluefire]

im going to put a diy co2 on my 39gal planted tank and i was wondering what can possibly go wrong and affect my fish and how do i prevent it, like how ive heard if the kh is wrong the ph will drop to 4?

 

[blue_ram]

im going to put a diy co2 on my 39gal planted tank and i was wondering what can possibly go wrong and affect my fish and how do i prevent it, like how ive heard if the kh is wrong the ph will drop to 4?

By DIY CO2, do you mean yeast+sugar mix CO2? Here are links to some disaster stories.

CO2 doesn't have any affect on KH, and vice versa; KH will remain constant, regardless of added CO2. Low KH value doesn't matter because KH will not buffer carbonic acid (CO2 dissolved in water). What this means is that adding CO2 will gradually lower your pH regardless of the KH. The amount of pH lowered depends only on the amount of CO2 dissolved in the water. Here's a link that explains more in detail.

You can control the pH drop by controlling the amount of CO2 added to the water. So can your pH 'crash' due to too much CO2? Absolutely. High pH/KH value won't help you in this case.

 

[smithrc]

Actually the higher the KH the the more Co2 you can add with out it effecting the PH.

Test your hardhess (KH) and you can then work out what sort of CO" figure you'll get with the PH staying safe.


I've got a KH of 8. this allows me to get arround 30ppm of CO2 int the water with the PH at 7.0.

By monitoring the PH you can see what the Co2 is at and change it if needed.

Start slow (eg a 500ml mix) and work up. for a well planted tank 30ppm is about right.

Just make sure you keep an eye on the PH and you'll be fine.

 

[Def]

PH isn't your only issue. If your CO2 runs 24hrs a day (and if you use the homebrew stuff, it will), you're going to have to watch your fish very carefully overnight. I nearly lost a lot of fish when using a CO2 - woke up one day and found them all gasping at the surface. Plants produce CO2 and use O2 at night, and if you're addding to the CO2 load you need to be really careful.

 

[bluefire]

well i have 2 air stones in the tank so i don't think lack of oxygen will be a problem. also is there any way i can do this safely without a kh test kit?

 

[enchanted]

It has been proven that airstones do not add any viable amount of oxygen to the water and CO2 has no relationship to the amount of O2 in the water.

What you need to watch for is an overdose of CO2, but if you do it right this will not happen.

When I say do it right I mean add 1 bottle, monitor for the amount of CO2 being produced into the water, add the second bottle, monitor again. You can get a good gauge of what each is adding so you know when you are getting close, but most people don't go over 3 bottles and on a tank that size 2 should be enough to get a reasonable level.

 

[bluefire]

i was only going to add one bottle. do you think that i should just add it because its hard without knowing the kh?

 

[smithrc]

just watch your ph - if it dosn't fall your ok.

Buy a KH kit though - it'll aid you in the long run.

If you've got the air stones in there though they will undo the work you put in because CO2 is easily taken back out of solution. the surface disturbance will get rid of it very quickly.

Edit for grammer

 

[smithrc]

what lights do you have BTW?