fishless cycling - pH problem?

Thusly "muddyfox" Spake Unto All:

I'm trying to cycle my new aquarium using Ammonia. Things seem to be
on track except that the pH is climbing to very high levels (pH 8.4
today) and I'm concerned that the bacteria I need for my nitrogen cycle
will not do well in these conditions.

Ammonia has a pH of about 10-11 so it's not all that surprising that
adding pure ammonia causes pH to rise.
pH 8.3 is also the equilibrium point for hard water, so if your water
has high KH that's the pH you're going to have when the CO2 in the
water is in equilibrium with the CO2 of the atmosphere.

That said, a pH of 8.4 wont inconvenience your de/nitrifying bacteria
in the slightest. You don't want the pH to go over 9.5, though.

I see others have suggested the rising pH may be due to
limestone-containing sediment in your tank, but that'll not be the
case - one can't raise the pH of a tank to 8.3 with limestone. I wish
one could, but the equilibrium point will be in the region of 7.5-7.7,
because the limestone dissolves so slowly.

Also, like others have noted, your tank is already cycled, as ammonia
& nitrite is zero, and nitrate is 30 ppm.

On a sidenote, using pure ammonia isn't really necessary, one can also
simply feed the tank sparingly (without any fish being in it). The
food will rot & provide ammonium for the de/nitrifying bacteria. I
don't know why so many seem to prefer to use ammonia; possibly it
seems cleaner & more controlled.

Mean_Chlorine wrote:
Thusly "muddyfox" Spake Unto All:

I'm trying to cycle my new aquarium using Ammonia. Things seem to be
on track except that the pH is climbing to very high levels (pH 8.4
today) and I'm concerned that the bacteria I need for my nitrogen cycle
will not do well in these conditions.

Ammonia has a pH of about 10-11 so it's not all that surprising that
adding pure ammonia causes pH to rise.
pH 8.3 is also the equilibrium point for hard water, so if your water
has high KH that's the pH you're going to have when the CO2 in the
water is in equilibrium with the CO2 of the atmosphere.

Yes the water is very hard around here and 8.3 is about where the tanks
are at my local fish shop so that all fits perfectly.




That said, a pH of 8.4 wont inconvenience your de/nitrifying bacteria
in the slightest. You don't want the pH to go over 9.5, though.

That's a real relief to know. I will keep an eye on it though, to
check it doesn't go up to 9.5.


I see others have suggested the rising pH may be due to
limestone-containing sediment in your tank, but that'll not be the
case - one can't raise the pH of a tank to 8.3 with limestone. I wish
one could, but the equilibrium point will be in the region of 7.5-7.7,
because the limestone dissolves so slowly.

Also, like others have noted, your tank is already cycled, as ammonia
& nitrite is zero, and nitrate is 30 ppm.

Unfortunately the nitrate I have comes directly from the tap water
rather than a completed cycle, in fact I think it's just over the level
which is regarded as safe in drinking water so I have reported it to
the water quality dept in our local water company.



On a sidenote, using pure ammonia isn't really necessary, one can also
simply feed the tank sparingly (without any fish being in it). The
food will rot & provide ammonium for the de/nitrifying bacteria. I
don't know why so many seem to prefer to use ammonia; possibly it
seems cleaner & more controlled.


Well I wanted to do it this way originally because it seemed more
natural and I wouldn't then have to muck about with ammonia but three
things put me off.

One was that someone said (somewhere on the internet) that this can
give artificially high levels of phosphate which, apparently, is bad.

Another was that I didn't really know how much food to give or what to
give. (Some folk put lumps of raw fish in the tank, others high
protien solid food and others flake.

Finally, people seemed to say different things about cleaning the tank,
some said syphon off the food every day, some said leave it all there
and other folk said everything else in between! I couldn't get a clear
protocol so I went for the ammonia in the end.

You sound very experienced. I would still prefer to use fish food so
if you have a clear way of doing this I'd love to hear it.

Many, many thanks for your very helpful advice and insight,

Muddy

Hi All,

Thanks very much for all your messages. You've really helped me out.
The pH fell back to 8.3 tonight and the tank began to cycle - Nitrite
at 0.50 ppm!!!



Really appreciate all your help,

Cheers,

Muddy