Co2 and pH problem

[Afishperson]

I'm having a problem with my Co2 causing my pH to drop. The tank lights and co2 are on from 9:00 AM to 5:00 PM. this morning I tested the pH before the lights and Co2 came on and it was between 7.2 and 7.6. But I just tested again at 3:30 PM and my pH tested at 6.4! My tank is still cycling (with plants in it) so there are no fish to worry about. My KH is 53.7 ppm. The Co2 is around 1 bubble per second. Could it be my KH is to low? I have a fluval Co2 checker and its always green so I'm assuming my Co2 is at an acceptable level.

Thanks!

 

[flash2121]

Seems you just described my tank. Hoping to see what people say.

 

[Old Scales]

Dear Fishperson,
I had to do some goggling to find that your 53.7ppm equals only 3 degrees KH. That's really soft water. My water is very soft also. (2 dKH in winter & 4 dKH in summer) When I when pressurized CO2 my pH would go from 7.0 to 6.2. I dosed a small amount of Baking soda (sodium bicarbonate) just enough to bring it up to 5 dKH. Now my pH swings from 7.0 to 6.6 which is safer and about normal for CO2. I measured and tested and found that 1 teaspoon in 25 gal. raises KH by 2 degrees. I put it in a small amount of water and mix until dissolved then put in the tank after each WC. Remember though that you don't automatically add 1 tsp each WC as some will still be in the water. You can test your KH after the WC and dose the baking soda at the amount to stay at 5-6 dKH.
For your calculation, 1 degree KH is 17.848ppm. Hope this helps. OS.

 

[Afishperson]

Dear Old Scales,
Thank you! That was very informative. Hopefully my tank will be fit for fish soon.
I'll try to post again to tell you how it goes.

Thx