Seisage
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Apologies for the long post ahead. Alright, so, I'm currently working on constructing an Ucayali River biotope. I just set up the tank yesterday and I'm really at a loss for how to cycle it.
My tap water's KH (and GH) is naturally extremely low, at around 35ppm (~2 degrees). The tank's pH is currently at 6.8, although my tap water is ~7.2. These parameters are near perfect for a blackwater tank, and that is exactly what I'm shooting for, as many parts of the Ucayali are soft, acidic, and tannin stained. Now, the problem is, of course, that traditional nitrogen cycling requires higher KH and ideally a higher pH. Many sources I've found recommend simply adding a source of KH to raise it. I really don't want to have to do this, as it would require constant maintenance to keep KH levels up long-term and I'd worry about how bringing the KH back down later would affect the bacterial colony. However, basically all sources say that traditional cycling simply isn't possible with KH below 50ppm.
Researching blackwater tank cycling or low KH cycling in general unfortunately hasn't been very helpful. I've found a lot of conflicting or otherwise unhelpful information. Many people recommend maintaining KH with regular additions of tap water, which... will not help in my case with my ridiculously soft water. Or, people recommend converting an existing tank to a blackwater one, but that requires having a cycled, mature tank to convert. Other people say don't even bother trying to cycle since the low pH means ammonia is non-toxic anyway. If possible, I'd like to avoid making that gamble and potentially losing fish because of it... There's nitrite to worry about too, anyway.
Now, I hear that the set of nitrogen-processing organisms in blackwater conditions is completely different than the typical players. Different bacteria, archaea, etc. How do I go about growing them? I imagine I should probably add leaf litter and botanicals now to get to a stable pH before trying any sort of cycling process, correct? Once pH is stable, what steps should I take to make sure the tank can handle fish bioload? How long does it usually take for the bacteria/archaea colonies to grow? I hear it takes at least a few months. Is it possible to add any fish at all before then, or do I just need to be patient and wait it out? If at all possible, I would appreciate somewhat direct instructions. Vague answers just leave me with more questions... If no instructions are possible, then so be it, I suppose.
FYI: I am aware of the recent blackwater cycling thread here, but it's ultimately more about maintaining a blackwater tank rather than setting one up.
Context which is likely important:
My tap water's KH (and GH) is naturally extremely low, at around 35ppm (~2 degrees). The tank's pH is currently at 6.8, although my tap water is ~7.2. These parameters are near perfect for a blackwater tank, and that is exactly what I'm shooting for, as many parts of the Ucayali are soft, acidic, and tannin stained. Now, the problem is, of course, that traditional nitrogen cycling requires higher KH and ideally a higher pH. Many sources I've found recommend simply adding a source of KH to raise it. I really don't want to have to do this, as it would require constant maintenance to keep KH levels up long-term and I'd worry about how bringing the KH back down later would affect the bacterial colony. However, basically all sources say that traditional cycling simply isn't possible with KH below 50ppm.
Researching blackwater tank cycling or low KH cycling in general unfortunately hasn't been very helpful. I've found a lot of conflicting or otherwise unhelpful information. Many people recommend maintaining KH with regular additions of tap water, which... will not help in my case with my ridiculously soft water. Or, people recommend converting an existing tank to a blackwater one, but that requires having a cycled, mature tank to convert. Other people say don't even bother trying to cycle since the low pH means ammonia is non-toxic anyway. If possible, I'd like to avoid making that gamble and potentially losing fish because of it... There's nitrite to worry about too, anyway.
Now, I hear that the set of nitrogen-processing organisms in blackwater conditions is completely different than the typical players. Different bacteria, archaea, etc. How do I go about growing them? I imagine I should probably add leaf litter and botanicals now to get to a stable pH before trying any sort of cycling process, correct? Once pH is stable, what steps should I take to make sure the tank can handle fish bioload? How long does it usually take for the bacteria/archaea colonies to grow? I hear it takes at least a few months. Is it possible to add any fish at all before then, or do I just need to be patient and wait it out? If at all possible, I would appreciate somewhat direct instructions. Vague answers just leave me with more questions... If no instructions are possible, then so be it, I suppose.
FYI: I am aware of the recent blackwater cycling thread here, but it's ultimately more about maintaining a blackwater tank rather than setting one up.
Context which is likely important:
- The tank is planted with frogbit and hopefully soon with water lettuce too
- No botanicals are added yet, except for foraged branches and twigs, but there is no visible staining (tank pH = 6.8)
- I'm aiming for a pH between 6.2-6.8, so nothing crazy (the species I plan on keeping aren't super fussy about pH). I'm not looking for advice on how to decrease my pH, since I expect leaf litter to do that well enough on its own
- Running a sponge filter, so no filter compartments or media bags to add anything to
- I have an existing planted 5.5gal which I believe is cycled, but I adopted it, so I didn't go through the cycling process with it. This tank's water is, of course, also very low KH. I seeded the new tank with gravel from this one and was planning on adding filter media from it to the new tank as well to help with seeding. This tank is at a pH of 7.2, so I suppose even if these bacteria are adjusted to low KH, they likely won't survive the pH shift with the humic substances anyway.
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