pH Too Low For Fishless Cycle?

[RPMick]

First post, long time reader/lurker. Fish keeping for a little over 5 years now, all freshwater community and all planted. I just recently moved and I was forced to downsize considerably and can now really only work with 1 tank in the house. That tank is destined to become a discus tank. So, here I am, a month and a half from fishless cycle start date and my parameters are still stuck. Hoping someone can help let me know if I'm on the right track or not.

Tap water tests at: Ammonia, NitrIte, and NitrAte all 0 and pH 7.2.
For the last 6, aquarium water tests at: Ammonia - 4, NitrIte and NitrAte 0, and pH 6.0.

I thought the 7.2 to 6.0 drop seemed a little extreme for 5 pieces of driftwood but I've never paid too much mind to pH in the past and never had this much driftwood in an aquarium before. Now I'm reading that low pH can inhibit a cycle or even impact long term colonization of bacteria. I"m getting close to adding a bag of crushed oyster shells or crushed coral to the filter in an effort to bring pH back up but I'm really looking for a long term solution that won't include either of those. Do I just need to be patient and let this run its course or am I fighting a losing battle trying to cycle a tank that reads at 6.0? I did just order a GH & KH test kit so I'll those numbers on Tuesday night if that's critical information to be considered.

-Ryan


Tank Vitals:
75 Gallon w/ stock T8 light
Rena XP3 Filter
2 250W heaters at 81 degrees
2 air stones running full time
PFS Substrate
No chemicals except pure ammonia added

Tank image in case the one below won't embed: https://www.dropbox.com/s/xxbq3ewq77...photo.JPG?dl=0

[Second Hand Pat]

Try lowing your ammonia to 2.0 ppm. I think at 4.0 ppm it is stalling your cycle. The ph is fine.

[RPMick]

Can do. Will give that a go tonight.

-Ryan

[nc0gnet0]

Low Ph will indeed impede the growth of beneficial bacteria.

[Second Hand Pat]

Low Ph will indeed impede the growth of beneficial bacteria.

Rick has a point so...

pH

The optimum pH range for Nitrosomonas is between 7.8-8.0.

The optimum pH range for Nitrobacter is between 7.3-7.5

Nitrobacter will grow more slowly at the high pH levels typical of marine aquaria and preferred by African Rift Lake Cichlids. Initial high nitrite concentrations may exist. At pH levels below 7.0, Nitrosomonas will grow more slowly and increases in ammonia may become evident. Nitrosomonas growth is inhibited at a pH of 6.5. All nitrification is inhibited if the pH drops to 6.0 or less. Care must be taken to monitor ammonia if the pH begins to drop close to 6.5. At this pH almost all of the ammonia present in the water will be in the mildly toxic, ionized NH3+ state.

http://www.bioconlabs.com/nitribactfacts.html

If you do a 50% water change this should bring to ph up of a more friendly level.

[RPMick]

Alright...finished my 50% and I'm at 2 for ammonia and now about 6.4 for pH. I'm still blown away at the fact that this driftwood is really bringing pH down this far. I'll check pH again tomorrow night and see where it has settled in at.

-Ryan

[pcsb23]

I'd take the wood out for now until the filter establishes. You may need to keep the wood wet else it may not sink when it goes back in . 2ppm is better to start with.

[RPMick]

Even if I removed the wood for the purposes of cycling, I would expect the pH to settle back to the low 6's again once added back. Low pH inhibits cycle start so wouldn't it also have a long term impact on sustaining the BB even with a bioload following the cycle?

-Ryan

[nc0gnet0]

sustaining and growing are two different things, once established it should be ok.

[RPMick]

Right on, thanks. It's actually quite exciting to be learning things about the hobby that I hadn't thought I previously had a need to learn before now. Also read today that the tannins are likely the root cause of the steep pH drop. It's Malaysian driftwood and I've only experienced very minor tannin leak in the past from it but I think with there being 5 relatively large pieces at once, it must be making a larger impact on the water column. I soaked 'em in the sun in a rubbermaid for about a week but they still did manage to discolor the water for a water change or two anyway.

I really don't plan to add my discus to this tank until sometime early next year and this is part of the reason to not make introducing them a priority. Like to have this thing well established before spending a large sum of money on fish. Am I being over cautious to a certain extent or would a pH gradually moving from 6.0 to 7.0 over a period of time be perfectly fine for the fish?

Thank you everyone for the input so far. Solid sources of information on here.

-Ryan

[adapted]

"The pH is also a vital factor in nitrification. Maximum rates of nitrification occur at pH values above 7.2, peaking at 8.3 (a common pH for marine tanks) then falling at higher values. What surprised me was the rate at which the effectiveness of nitrification dropped in acidic pH values: to less than 50% optimal efficiency at pH 7.0, to just under 30% at pH 6.5, and to just over 10% of maximal efficiency at pH 6.0. At these low pH values, nitrifying bacteria don't die, they just stop metabolizing and reproducing. Of course in these acidic conditions, most of the toxic NH3 is ionized to non-toxic NH4. But I had been under the impression (and had mentioned here) that the pH needed to drop quite low, below pH 4.8, more like the acidity of a peat bog rather than conditions in a home aquarium, to repress nitrification. Not so."

http://www.skepticalaquarist.com/nitrogen-cycle

[pcsb23]

I've got posts on here that show that nitrification MUST be happening at pH of well below 4 ...

A word on tannins, they are a bactericide so may be having an effect on the developing the filter bacteria, another reason to remove the wood.

[RPMick]

Update on my situation...pulled the driftwood out, did 75% water change w/ Prime, pH returned to 7-7.2, and here about 5 days later I have nitrIte showing up. Many thanks to those of you who provided input and information along the way. Finally feel like this aquarium is starting to move forward.

I'm certainly going to wait until the cycle completes before the driftwood & plants go back in, but can I expect long term challenges in bacteria growth when new stock is added? If i'm going with a large number of tetras, would the low pH make conditions ripe for an ammonia spike?

My only other complaint is the dual heater setup. Running two 250w Jager heaters, keeping the aquarium at 81 +/- 1, and one of the heaters seems to want to be always on and the other perks up only periodically. I calibrated both of them to 81 individually, but now they have minds of their own...but I digress. I'll roll this conversation over to the equipment board though. Thanks again!

-Ryan

[MendoMan]

If you want to get the tannins out and you have a pot big enough you can boil them out. I did my large pieces with an outside burner in a big pot. Worked great. The only way I know that you can get both heaters to operate exactly the same is to have them on a controller.

[pcsb23]

Update on my situation...pulled the driftwood out, did 75% water change w/ Prime, pH returned to 7-7.2, and here about 5 days later I have nitrIte showing up. Many thanks to those of you who provided input and information along the way. Finally feel like this aquarium is starting to move forward.

I'm certainly going to wait until the cycle completes before the driftwood & plants go back in, but can I expect long term challenges in bacteria growth when new stock is added? If i'm going with a large number of tetras, would the low pH make conditions ripe for an ammonia spike?

My only other complaint is the dual heater setup. Running two 250w Jager heaters, keeping the aquarium at 81 +/- 1, and one of the heaters seems to want to be always on and the other perks up only periodically. I calibrated both of them to 81 individually, but now they have minds of their own...but I digress. I'll roll this conversation over to the equipment board though. Thanks again!

-Ryan

Ryan, once you get your filter colony established, provided it gets food (i.e. ammonia) then adding back the wood won't be an issue. Even without adding the wood back the pH will fall as this is a consequence of the nitrogen cycle - the end result is a form of nitric acid.

I'd be happier of you set you heaters to cycle at 82 to 83 f for discus and the best way to deal with two heaters is to use an external controller and feed both heaters of the same controller.

Oh, and imo/e tannins are a good thing