Recommended Ph Range For Ammonia-Bacs Versus Nitrite-Bacs

[Gvilleguy]

One thing I am not clear about is what level of pH is recommended for transitioning from the ammonia phase to the nitrite phase of a fishless cycle. I've seen posts that say the nitrite bacteria might grow better at a lower pH level, compared to the ammonia bacteria that prefer 8.0 - 8.4.

1. At what point in the cycle would you think someone should lower the pH from the 8.0 - 8.4 range during the ammonia phase? When ammonia first drops to zero, or perhaps when it's going to zero in 24 hours?

2. Does anyone know what pH level the nitrite bacteria might prefer?

Thanks,

GVG

 

[Whitey_144]

One thing I am not clear about is what level of pH is recommended for transitioning from the ammonia phase to the nitrite phase of a fishless cycle. I've seen posts that say the nitrite bacteria might grow better at a lower pH level, compared to the ammonia bacteria that prefer 8.0 - 8.4.

1. At what point in the cycle would you think someone should lower the pH from the 8.0 - 8.4 range during the ammonia phase? When ammonia first drops to zero, or perhaps when it's going to zero in 24 hours?

2. Does anyone know what pH level the nitrite bacteria might prefer?

Thanks,

GVG

i assume people will advise not to mess around with the PH at anytime, so including the cycle.

what PH is yours? mine is 8 and both A bacs and N bacs seem to be doing what i expected, i think the nbacs colonise slower anyway.

 

[Gvilleguy]

It's fine to mess with pH during a fish less cycle. It's just not recommended once you have fish in the tank. My pH is 6.0, so if I didn't raise it my cycle would not happen at all. I've already completed all my cycling, I'm just curious about the nuance of modifying pH for A-bacs versus N-bacs.

 

[Aqua Tom]

A ph of 8ish is what you are after. If you have a low ph you can raise it with bicarbonate of soda.
1 teaspoon per 10 gallons, obviously this can only be done with a fishless cycle.
Once the cycle is over you will do a massive water change to get rid of the bicarb.


~Tom~

 

[waterdrop]

The 8.0 to 8.4 pH range is optimal for both of our autotrophs. The idea that it was only one or the other must be some artifact of the communications passed around in the last few months (you know that game with the circle of chairs and the phrase is whispered to the person on your right all the way around until when you get the phrase back it has altered?... )

While the graph or information that that shows the 8.0 to 8.4 plateau for peak growth rate comes from Hovanec when studying Nitrospira, it seems to hold basically true for both of ours (and probably a whole range of similar autotrophs) and of course on a practical level we have to always keep in mind that the tools we hobbyists are using (dosing bicarb) don't give us much precision anyway. I suppose theoretically one might wonder if someday someone will put up a lab full of tanks and measure peak growth rate directly for Nitrosomonas and find it is a small bit different from Nitrospira but first I'd not hold my breath for that (probably Tim has a family to worry about by now, lol) and secondly I'd venture to guess the optimal is probably right in the same range if not identical.

All of this still falls into the "tweeking" catagory, although there are certainly circumstances (like me and GV for instance, with our soft, acid water!) where I think bicarb can really help, big time. I've grown less and less hesitant to recommend it, even early in the game, over time. There is an school of thought though that if one's tank pH (after dechlor and settling into the tank but before fishless cycle is started) is reasonably high enough, say 7.6 and up perhaps, then one might just leave well enough alone and wait to see how the carbonate hardness situation plays out. If the cycling process does indeed knock it lower over time (and the process will always be pushing in that direction of course) then at some point later bicarb can begin to be used.

What I'm saying is that plenty of people can happily fishless cycle without this intervention and it should never be thought that it is some sort of must if the pH is not in the 8.0 to 8.4 range. Instead, it should be understood that it gradually increases in desirability as one's hardness/pH situation decreases numerically.

~~waterdrop~~

 

[Gvilleguy]

Thanks, guys. That clarifies for me a great deal. I don't want to pass around bad advice, so this helps a lot.