co2 question

[Swimfins]

I just set up a 2 litre do it yurself using the formula with sugrar and yeast.
I've got the tubing going into the intake of my filter. Tank is 20 g or so with 40 watts of light.

ph is now about 6.8, gh is 100 and kh is 50 according to my master test kit.

My tap water is 7.8.

What will happen during water changes when I introduce the higher ph to my tank? Is there anything I should do?

 

[djlen]

First run another kH test because you are posting a low kH that could be dangerous to your fish when injecting. You need a 3.0°H buffer(minimum) to be safe. You are reporting 2.8°H.
The reason I suggest another test is because it is unusual for a tank's kH to be that low with a 7.8 ph out of the tap. CO2 injection does not change a water's kH.
Your test kit probably requires a drop = 1°H(17ppm). Instead of using that formula, put double the amount of tank water in the vial and count each drop of test reagent as 1/2 a point(2 drops = 1 point, 5 drops = 2.5 points, etc.). This will give you a more accurate number.
If you still come up with 50ppm(2.8) you will need to mix in some baking soda to raise your kH up to 3.0 - 3.5. How much baking soda you'll need depends on the size of your tank. Crushed coral is a better long term option than baking soda, but since you are already injecting you can go with the soda and pick up the coral at the LFS for long term safety. Coral takes a longer time to become effective, but is more consistent at holding kH.
In answer to your other question, I keep my tanks at pH = 6.5 and my tap water is 7.4. I do weekly 50% or better water changes and the pH swing when changing water is minimal and doesn't affect the fish negatively at all. They like their water changes.

Len

 

[Swimfins]

Thanks for your reply. I just redid the test using a full test tube. Besides the initial first drop, it took 2 drops to turn the solution yellow.


according to the calculator in chuck's planted aquarium,

my ph is 6.8 kh 2.8 degrees or (50 ppm) and co2 is 13.3 which is safe isn't it?

 

[djlen]

What size(in gallons) is your tank?

Len

 

[Swimfins]

25g long

 

[djlen]

You are probably going to be alright with what you've got, but if it were my tank I would work to bring that kH up to 3.0 - 3.5.
We have had cases of pH dropping out and fish kills from too low kH buffer.
In a tank of your size, with only one bottle of mixture you may be OK. But I'd advise raising it a bit.

Len

 

[Swimfins]

ok thanks for the advice. I'm just a bit afraid to start messing and adding bicarb, everthing seems ok right now. The fish don't seem stressed, maybe the crushed coral might be a good idea however.