7 Weeks Into Fishless Cycle And Ph Has Crashed Again

[yabadaba]

Hi, I'm into the 7th week of my fishless cycle and believe it's very close to completion, but today I noticed that the ammonia had not been processed back to zero as expected, so tested my pH and found that is back to 6 again. This happened for the first time about 10 days ago and a 50% water change rectified things, so I guess I'll have to repeat that. But, what I was wondering is whether the low pH has any effect on the beneficial bacteria - i.e. does the low pH simply stall the ammonia processing or can it actually kill-off the bacteria and set the cycle back?

 

[waterdrop]

No, the more rapid drop of the pH through the 6's shocks the bacteria into inactivity. Even at a very low pH they would eventually begin to slowly process again but at a much, much lower rate than if the pH were up in the 7's or 8's. This inactivity and slow revival though is way too slow for a fishless cycle. I'd recommend that if you -do- do a water change that you take the time to do it all the way down to the substrate and actively gravel clean while the water is going out. This gets the nitrite & nitrate compounds (which hang closer to the gravel sometimes) out to a much larger extent than a partial change and you might also consider dosing baking soda (not baking powder) at a rate of 1 tablespoon per 50L to help raise the KH and pH. The baking soda leftovers will all go out with the big water change before fish.

~~waterdrop~~