Can nitrifying bacteria grow at a low PH?

swabler

Hi All,
I'm new to this board and think its a great place to hang out and learn.
I'm trying to cycle my new aquarium. Its been about 4 weeks with a few fish and constant ammonia at 1-2 PPM. Using prime and frequent water changes. The little guys have been fine. I have a low PH, fluctuating around 6.5, so I believe the ammonia is being ionized and harmless at that PH. Is this true?

But my main question is can I create enough beneficial bacteria at a PH of 6.5, which I've read is only 30% of optimal, to cycle my tank?

Thanks,
Lolita

1077

If you have live fish in the tank with ammonia level's posted,,I would be glad that the ph is 6.5 and would be performing water changes daily to lower it .
Bacterial colony will develop a bit slower but it WILL develop.
Water changes and reduced feeding's,and or live plant's will help fish survive.

swabler

Thanks 1077! I've been doing daily water changes and reducing their food and there are a few live plants. Also adding some bottled bacteria everyday but I'm not sure what that is actually doing besides making me poorer.

I was thinking of raising the pH just to get the bacteria going but, then again, at some point the ammonia will start to have an effect with the higher pH, right? Its a catch-22?

Anyway, haven't lost any fish yet though a Discus I bought from the LFS very cheap is showing signs of fin rot though it doesn't seem to very stressed at all right now. It was on its side in the pet shop when I bought it right after its arrival from who knows where. It was very cheap and I couldn't resist it. That was a mistake I guess.

Someone told me it must be a wild one to be sold so cheap and wild ones were full of parasites. I dont know what to believe about all this. Since I've started this hobby I've heard so many versions of the truth about everything. Its all confusing!

I really appreciate the feedback, thanks
Lolita

AbbeysDad

For what it's worth, I would never buy a fish that appeared sick or diseased or came from a tank that contained any sign of disease - not for any price or even as a gift. Imagine contaminating a large tank with a disease or parasite because I saved a buck on some sick fish?! - no thanks!

As far as your original question, I believe (not to be confused with facts!) that bacteria can exist in a wide range of water parameters...perhaps even wider than most fish. I don't think I'd attempt to routinely manage pH unless my water simply would not support fish (fortunately, I think my well water is pretty good in that regard).

Byron

There are a couple of issues in this thread which I will comment on individually. First, though, allow me to welcome you to Tropical Fish Keeping forum. Glad you joined us.

Always research a fish before buying it. Most have certain specific requirements that have to be provided for optimum health. Aside from the disease issue [and I agree with AbbeysDad on that], Discus should be in groups, they are shoaling fish. They need space, a 4-foot tank (55g) is minimum. Enough on that.

To the initial question on bacteria and pH. Nitrifying bacteria--and there are many types of bacteria at work in an aquarium, but we are here talking only about the bacteria responsible for the nitrification cycle--are impacted by water parameters such as pH and temperature. This is explained in more detail in my article, so please have a read so I don't have to repeat all that:
Bacteria in the Freshwater Aquarium

To summarize, nitrifying bacteria will slow considerably as the pH becomes more acidic, to the point where it stops completely. Fortunately, with live plants it doesn't matter much; the plants will assimilate all the ammonium [you were correct, in an acidic pH ammonia changes to ammonium which is relatively harmless to fish] and as they do not produce nitrite, that's the end of the matter. Some bacteria will colonize, but it will be minimal. You won't detect ammonia or nitrite with most test kits.

Which brings me to your ammonia reading. Have you tested your tap water for ammonia? Also test it for nitrite and nitrate; this is good to know just in case one or more are present in the source water. How large is this tank, how many and what type of fish are in it, and how many and what type of plants are in it?

Byron.

swabler

Thanks very much for the advice Byron. I've only started this a few months ago and have made plenty of mistakes along the way and have a ton to learn.

This past summer I set up a 65 gallon tank with a 5 gallon internal wet/dry trickle filter chamber. Originally I only had a few cups of bio-balls in the chamber but decided to submerge about a liter of ceramic balls and just recently another liter of seachem matrox and a bunch of nylon pot scrubbers thinking the more bio-media I had the better. For the chemical filter I used carbon and zeolite but removed this a few days ago when I started using PrimaFix and MelaFix for what I think is a fin rot problem with one of my Discus. The stressed one I foolishly bought in a LFS.

I have 3 other Discus that I bought from a breeder in NJ. Also there are 4 small angels, a golden nugget pleco who I hardly ever see and three silver dollars that are about to be donated to the LFS. And finally I have 2 small electric blue balloon rams that I love. The fish all seem healthy except for the suspected finrot in the LFS Discus.

Early on I made a mistake about 4 weeks into cycling by washing my bio balls in tap water. That set the tank back. But my biggest mistake was not waiting for the tank to complete its cycle before buying fish. I use prime and do frequent water changes. My tests dont show any ammonia in the tap water. I'm lucky that in New York the water has a low pH.

I put a 2 cup bag of crushed coral in one chamber to try to keep the pH above 6.5 when I was worried I wasnt creating nitrifying bacteria quickly enough because of the low pH. Last test I did yesterday before a 50% water change showed ammonia at 2 ppm, no nitrite or nitrate. I assume the ammonia has been ionized and don't worry much as the fish are looking happy even the yellow Discus.

My substrate is about an 1.25 inches of floramax and an inch of petco gravel mixed in with some petco sand.I never realized that the substrate was relevant for BB till I read your excellent article Byron. I have been vacuuming the gravel everyother water change. I'm just beginning to plant and have 1 pennywort (a favorite food of the silvers), 1 Anubias, 2 hogwort (not doing to well), a jave fern and some other plant i cant remember. I'm looking at extraplant.com and thinking about making an order for a bunch more. have a 65 watt coralife full spectrum that i keep on 10 hours or so.

Any thoughts, comments or suggestions are most welcome and appreciated.

Thanks,
Lolita

Byron

I would remove the crushed coral, but I am intrigued that with 2 cups the pH is not much higher. What is the pH of the tap water (presumably this is your source water)? And the hardness (both GH and KH)? I only have about 2 tablespoons of aragonite/coral mix in my 115g filter and the pH is around 7 (without the aragonite/coral it is at 6).

swabler

Thanks, the tap water pH is 6.4. I removed the coral. The coral was in for less then a week and there have been a few diluting water changes since. I've been doing 40% changes. Haven't tested for hardness yet but NYC water is known to be soft. I will test for that soon. It an area I don't know much about.

The pH was 6.6 today without carbon. Ammonia was 1ppm but I'm believing its ionized ammonia at this pH and not harmful to the fish? And the ionized ammonia will still trigger the nitrifying process in my bio filter.Is this OK. What am I missing? Thanks

Byron

If you already have the hardness test kit, fine, but if not, don't bother. You can find out the tap water hardness from the water supply people, some have a website or they can tell you directly. Unless you intend fiddling with hardness, that will suffice.

I would leave things as they now are, and keep tabs on the pH. Once we have the hardness numbers, we will have a better idea of how much it may lower and how fast it will do this. Continue water changes, normally I recommend once weekly with 50%, you have Discus so do whatever you've been doing previously.

The ammonia is ammonium at an acidic pH so that is no harm. And baqcteria will use ammonium/ammonia as the same, though more slowly as was explained previously. Live plants further assist this. At this stage I recommend letting things stabilize and monitoring the pH. Always test prior to a water change so you have an idea of where the tank is going.

Byron.