PH crash during fishless cycle

I'm in the middle of a fishless cycle. Things had been moving along nicely - 2ppm of ammonia (Dr. Tim's Aquatics) drops to 0 in about 48 hours, nitrites are spiking (over 2ppm at least but I find it hard to read the colour beyond that), and nitrates are starting to build. Since I set the tank up at the beginning of April until a few days ago, pH was holding steady at 7.0. Today when I tested it bottomed out the API pH test. So I bought a pH meter and the tank pH is testing at 5.6.

I'm not sure exactly how/why the pH has dropped so much in, at most, 3-4 days when it was steady before. Or whether the low pH is going to negatively impact the fishless cycle.

Is this going to stall the cycle? Should I do a water change to bring the pH back up a bit? Just monitor the cycle closely and see how it goes? Any other suggestions?

Water parameters (today)

Tank:
pH - 5.6
Ammonia - 0.25
Nitrite - 2.0+
Nitrate - 20
KH - 0
GH - 4

Tap:
pH - 7.2
KH - 2
GH - 4
Ammonia/Nitrite/Nitrate - 0

 

Change your water....as much as you want really.

Your KH is so low that the nitrate is causing your PH to bottom out. You need some sort of buffer in your tank (maybe crushed coral) to help raise your KH and it will help your PH stay a bit more steady.

What type of organic material do you have in your tank? And plants, wood, leaves etc?

 

Yeah sure just do a 100% water change, that’s one easy way to hopefully resolve the issue.

 

test your source water and it's KH2, GH4.. this is low KH and low side GH. the GH is ok at 4, but it's low. the KH being 2 is the problem and why your pH is unstable. Both parameters should be between 4-8

And yes, as Bwood22 said, the nitrate is killing what little KH you have and this will give you wild swings of your pH in short periods of time. Lowering the nitrates won't help and a water change will just bring you back to 2 KH which will get rocked again by the nitrates.
Calcium Carbonate is the answer, baseline for it is really 1 pound per 10 gallons in the substrate. this will raise your calcium content and your GH, and also raise your carbonate content and your KH. of your water to stable levels and if there's a change to pH, more or less will be released and stabilize your pH without it going wild on you.

Calcium carbonate is Crushed coral, Limestone, oyster shells, cuttlefish bone, there's a lot of different sources you can use, But you need more than a little bit in order to have it really affect things and have reserves available to become dissolved solids in the water when needed for longevity.

I find cycling moves quickest, best beneficial bacteria reproduction and growth of the biological filter at 78-80F temperature, and around pH 7.0-8.0.. you need to raise up that dKH to at least 3. if not 4 or 5 or 6 to give you a safety net of buffer.

 

Your KH is so low that the nitrate is causing your PH to bottom out. You need some sort of buffer in your tank (maybe crushed coral) to help raise your KH and it will help your PH stay a bit more steady.

This tank is going to be a faux/quasi blackwater setup (can't go for true blackwater as I don't have RO/DI and it may not be feasible to set that up in my rented apartment). So in the long run the low KH and pH aren't necessarily a bad thing. Large water changes could cause pH swings but I'm able to do more frequent smaller water changes if necessary.

I'm more concerned about whether the low pH is going to kill the cycle? A slower cycle I can deal with.

What type of organic material do you have in your tank? And plants, wood, leaves etc?

Lots of driftwood and some plants (anubias, java fern, moss and floating plants). Haven't added any leaf litter/botanical yet.

test your source water and it's KH2, GH4.. this is low KH and low side GH. the GH is ok at 4, but it's low. the KH being 2 is the problem and why your pH is unstable. Both parameters should be between 4-8
...
I find cycling moves quickest, best beneficial bacteria reproduction and growth of the biological filter at 78-80F temperature, and around pH 7.0-8.0.. you need to raise up that dKH to at least 3. if not 4 or 5 or 6 to give you a safety net of buffer.

Although those parameters may be ideal for cycling, it's not necessarily the ideal parameters for my tank long term. I'm more concerned with whether my tank can cycle under the conditions I have rather than what conditions would make it cycle fastest.

I'm ok with the cycle taking longer than it would with 'ideal' parameters if it means the parameters I have are more suited for the tank long term.

 

Although those parameters may be ideal for cycling, it's not necessarily the ideal parameters for my tank long term. I'm more concerned with whether my tank can cycle under the conditions I have rather than what conditions would make it cycle fastest.

If it is not ideal parameters for the tank long term, you should go with what you plan for long term, minus temperature - that can change without an issue. But yes, for example pH - different species of nitrifiers are adapted to different pH. If you want your pH to be below 7, then it's better to have your pH below 7 from the start so that you grow the right species adapted to said pH. Otherwise you'd just be wasting time growing species that once your pH decreases, exhibit a much lower nitrification rate, or worse, stops working entirely. So question is - what pH, etc. are you aiming for?

 

I couldn't have said it better myself.
Azedenkae is spot on.
Nitrosomonas is a genus of nitrifying bacteria that is responsible for converting ammonia to nitrite. There are several different species of nitrosomonas that live and thrive at different PH levels. Same with Nitrobacter bacteria that converts nitrite to nitrate.

Alot of folks will tell you that if your PH drops while cycling your tank then your cycle will stall.
That's because now, all of the sudden, the bacteria that were growing and thriving at a PH of 7.0 are now dying off and a new bacteria strain will take that is better suited for the conditions.

That's another reason why a stable PH is so important.

Let the tank be what it needs to be....and cycle it.

 

This tank is going to be a faux/quasi blackwater setup (can't go for true blackwater as I don't have RO/DI and it may not be feasible to set that up in my rented apartment). So in the long run the low KH and pH aren't necessarily a bad thing. Large water changes could cause pH swings but I'm able to do more frequent smaller water changes if necessary.

I'm more concerned about whether the low pH is going to kill the cycle? A slower cycle I can deal with.


Lots of driftwood and some plants (anubias, java fern, moss and floating plants). Haven't added any leaf litter/botanical yet.



Although those parameters may be ideal for cycling, it's not necessarily the ideal parameters for my tank long term. I'm more concerned with whether my tank can cycle under the conditions I have rather than what conditions would make it cycle fastest.

I'm ok with the cycle taking longer than it would with 'ideal' parameters if it means the parameters I have are more suited for the tank long term.

Well it will take longer below pH6.8. It will take much much much longer below 6 if at all. Best idea is to cycle it then lower it where you want it. But no idea why you're really doing it...... depending on how "blackwater" you're wanting to go cycling is pointless.
It will take 4 months to 2 years to get low pH nitrifiers like archaea built up in sufficient numbers. But not for nothing Ammonia gets locked up at lower pH and isn't harmful same goes for nitrite and nitrate in large amounts. If ammonia is locked to ammonium it's not becoming nitrites, it's being processed to nitrates directly. Even then the low pH nitrifiers aren't doing the "work" the ammonium is being oxidized by the acidic water and converted to nitrates directly (its why with Old tank Syndrome nitrates skyrocket)

And if you don't have RO water which is starting around pH 6-6.8. You can start with distilled water that's around pH 5.5.
Just going to say if you intend to go to black water, you are wasting your time trying to cycle normal nitifiers, there won't be anything available for them to consume and they all will die, in a long time low pH nitrifiers will move in and colonize, but you don't really need them because at low pH the water isn't harmful. It's all bound as non-toxic components.

The whole catch on low pH fish and black water is bacteria. It's devoid of bacteria, good or bad. Low pH fish would do fine at higher pH "IF" they weren't getting exposed to a ton of bacteria with it. That's what kills them, not the pH, all the bacteria in the water they've never experienced before in low pH. Kept super clean and clear low pH fish can be kept successfully at higher pH water.

Blackwater is quite a challenge. I suggest you read everything you can on the subject before attempting it for real. Good luck to you.
If I'd know you were aiming to do blackwater from your first post with this cycled tank I would have told you cycling is just a wate of time. None of that bacteria will survive blackwater pH.

This is what got me. I have a tank going on like 6 years of no water changes and only topping off.. and deep into old tank syndrome. When I found this site, the recommendation was to do a lot of small water changes and it would turn around. I started the water changes and after a month and a half of ever other day 20% changes, NOTHING has been accomplished to turn it around I'm still right where I was with it.

And after much reading I'm fairly certain when the pH comes up finally, ammonia that is locked up is gonna come flooding in unbound again and my archaea is gonna die and no higher pH bacteria to handle the ammonia,, and then my fish are gonna get hammered by bacteria they haven't seen in a really long time. A month and a half of 15 gallon water changes every day and my pH is still 4, my KH is still 0, 0 ammonia, 0 nitrites, over 300GH and over 300 Nitrates.
Funny thing is my tapwater I us is 5dKH. It goes in the tank and it's gone instantly.

You can recover OTS through water changes if it's a new development but not if it's been like that for years. My drain and fill and attempt to reaclimate the fish idea of recovery is the right and faster answer. Because when the pH comes up (if ever) those fish are as good as dead from ammonia unlocking and then from a flood of bacteria that wasn't present, so being gentle and slow about it won't save anything. I might not save the fish doing it fast and trying to trickle acclimate either though.

Blackwater is even more complicated. OTS happens from being neglectful and lazy. blackwater is intentional and determined and controlled.

I can't emphasize enough the importance of learning everything you can on the subject in order to be successful at it long term if that's what you want to really do.
Good luck!

 

It will take 4 months to 2 years to get low pH nitrifiers like archaea built up in sufficient numbers. But not for nothing Ammonia gets locked up at lower pH and isn't harmful same goes for nitrite and nitrate in large amounts. If ammonia is locked to ammonium it's not becoming nitrites, it's being processed to nitrates directly.

Huh?.....Citation Needed.
Where are you getting your information?
Ammonium is what we recommend to everyone performing a fishless cycle.... it most definitely converts to nitrite first then to nitrate and absolutely does not take 2 years at a lower PH.

The whole catch on low pH fish and black water is bacteria. It's devoid of bacteria, good or bad. Low pH fish would do fine at higher pH "IF" they weren't getting exposed to a ton of bacteria with it. That's what kills them, not the pH, all the bacteria in the water they've never experienced before in low pH. Kept super clean and clear low pH fish can be kept successfully at higher pH water.

Edited: The whole catch on low pH fish and black water is MINERALS. It's devoid of MINERALS, good or bad. Low pH fish would do fine at higher pH "IF" they weren't getting exposed to a ton of MINERALS with it. That's what kills them, not the pH, all the MINERALS in the water they've never experienced before in low pH. Kept super clean and clear low pH fish SHOULD NOT be kept successfully IN higher pH water.

 

Ammonia is pH 11. The lower the pH from there the more ammonium and the less Ammonia there is,, it's picking up a ion,, and goes form NH3 to NH4+.down around 6.8 the vast majority if not all of it is NH4+.
Yes ammonium breaks down at pH6.8 and higher with bacteria at 6.8 and higher being available. Ammonium can be broken down by those nitirifiers and ammonium is a safer form of ammonia. ( though if pH is 7+ there is both NH3 and NH4+, just most of it is NH4+ and just a small percentage remaining as NH3).
However what I was saying is when we get down to below pH6 and under those bacteria aren't present, below pH6 and lower to pH4 ammonium is ONLY ammonium. its oxidizing from the acidic water and becoming nitric acid and then eventually nitric oxide, eventually nitrates in the water. If there's "nitrites", I've never seen them on a test personally.

I got this info from aquaponic nitrate production theories. Keeping water at 6.5pH all fish waste being held as ammonium and trickeling them to a reactor as the NH3 with temperature rise, instead of at higher pH as a more dangerous to fish form as all ammonia, and controlling the pH at 6.5 because if it gets much lower than 6 you don't get the nitrifying bacteria you need to break the ammonium( the small percentage of ammonia).

At low pH it's a completely different method and organism to break the ammonium to nitrogen, it's archaea, a single celled organism, similar in size and appearance to bacteria, and used to be thought as a bacteria but its not a bacteria and it's a longer, much much slower process to complete the nitrogen cycle.

The next part would be a which came first chicken or the egg discussion.

Low pH blackwater is mostly devoid of minerals, and salts, both of which are needed for bacteria to survive and thrive.

You want to argue the minerals and salts kill the fish and I say it's the bacteria that live in the mineralized environment that does it. Either way the fish is dead. However you can keep low pH fish in super clean and clear average pH, you can also keep average pH fish in soft or hard water, and you can keep hardwater fish at normal pH. They do acclimate and osmoregulate, what they can't do is build an immune system to pathogen build up that they've never experienced at the snap of the fingers.