Ph During Fishless Cycle

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tiguardo

Aquarium Advice Freak
Joined
May 10, 2011
Messages
339
Location
Devon, Uk
Hi all.

I'm three weeks into my latest fishless cycle and I'm getting a slightly unusual ph reading.

Our water here has a ph of around 6.5, which has never caused me any problems cycling. Tonight I have performed my tests and my readings are:

Ammonia 1.2 (which drops from 4 over 24 hours)
Nitrite 3.3
Nitrate 110

My Ph is reading 5.5 tonight. It has slowly risen from 6.5 over the past couple of days. Will this effect my cycle too much? I'm considering adding some crushed coral, but im wondering if a big PWC would help instead?
 
Yes, I'd bring the pH up. Nitrification is in inhibited at around 6.5 ph and gets worse as the ph gets lower. The bright side is that nearly all of the ammonia is in the less toxic ammonium form at this level, so it'd take an insane amount of ammonia to kill any stock that is in the tank, if you weren't going fishless.
 
I definitely agree with jeta that it needs to be brought up. Another thing to keep in mind is that if it's dropped that low once...I can virtually guarantee it will continue happening as you get deeper into your cycle making it very difficult (if not impossible) to finish without tons of water changes to refresh the pH. So I'd definitely recommend using a product like aragonite sand or crushed coral in a mesh media bag to buffer the water and hold pH steady at least while cycling...if not permanently to prevent sudden crashes once the tank is stocked. I have to run a very small bag of CC in my filters because my alkalinity is virtually 0...and my water has the tendency to dramatically drop the pH within a few days of a pwc without it.
 
Thank you gentlemen for your comments. Why do you think I'm having dropping ph on this cycle? I've not had a drop to this degree on my other tanks & don't think I'm doing anything different this time! My ammonia is dropping very quickly & as my readings show I've tons of nitrite & nitrate. Just that **** ph that's causing problems :)
 
Yeah, I'll agree with that. In my area a low pH and low alkalinity go hand in hand, so there's naturally less buffers in the water to keep pH stable. You'd also be surprised how different tap water (whether from a well or municipality) can change from day to day. During a fishless cycle the nitrifiers are pumping out acidic waste while consuming what buffers there are at the same time. That's what causes these dramatic pH crashes. One the tank is cycled and stocked...it may not be as big of an issue since in a reasonably stocked tank you're never asking the bacteria to chew through 4ppm in a day...so there will be less of this acidic waste produced.

I think it was jeta who made the point a while back that a healthy pwc schedule is crucial with low alkalinity water so you're constantly refreshing the buffers and preventing crashes once stocked.
 
One month into my cycle. Ammonia still dropping rapidly, with tons of Nitrite & Nitrates. Ph still a problem, sitting at 6, which to be fair is our usual ph, but I think it's slowing things down still.

Did a 50% PWC today, added some crushed shells from my LFS, who also suffer from same sort of ph, and added a filter foam from my established tank to help things along. Tested about 45 minutes after my PWC & my NO2 & NO3 are still off the charts. Is that normal??

Bit early to tell on the ph I think. Will test gain tomorrow.
 
tiguardo said:
One month into my cycle. Ammonia still dropping rapidly, with tons of Nitrite & Nitrates. Ph still a problem, sitting at 6, which to be fair is our usual ph, but I think it's slowing things down still.

Did a 50% PWC today, added some crushed shells from my LFS, who also suffer from same sort of ph, and added a filter foam from my established tank to help things along. Tested about 45 minutes after my PWC & my NO2 & NO3 are still off the charts. Is that normal??

Bit early to tell on the ph I think. Will test gain tomorrow.

If you can hold pH steady...you probably would have been done quite some time ago. Nitrification slows around 6.5 and stops entirely at 6. You basically right now your cycle is sitting at a red light and not moving at all. If it stays there...the tank will literally never cycle. You did the right thing with the large pwc and crushed coral.
 
eco23 said:
If you can hold pH steady...you probably would have been done quite some time ago. Nitrification slows around 6.5 and stops entirely at 6. You basically right now your cycle is sitting at a red light and not moving at all. If it stays there...the tank will literally never cycle. You did the right thing with the large pwc and crushed coral.

Thanks. It's strange as my other tank & my mother in laws tank both cycled ok, even at 6 ph. I didn't have to used crushed coral, and didn't even seed the tanks. For some reason this one is different!

Eh, nothing like testing your patience, lol!
 
A pH of 6 is a tricky area. When you get below it the bacteria simply stops converting...there is no nitrification. At the same time though ammonia is not toxic (within reason) at those lower pH levels. If the tank technically is not cycling it seems crazy...but since the ammonia isn't toxic, normal pwc's really handle it. NitrItes are toxic at that level...but since there's no conversion...ammonia isn't being turned into nitrIte anyway. Like I said...a bit tricky. The tanks of yours that cycled must have had a pH level above 6...otherwise it's just not going to happen. When it gets low (but still above 6), it slows exponentially...but will still happen.
 
eco23 said:
A pH of 6 is a tricky area. When you get below it the bacteria simply stops converting...there is no nitrification. At the same time though ammonia is not toxic (within reason) at those lower pH levels. If the tank technically is not cycling it seems crazy...but since the ammonia isn't toxic, normal pwc's really handle it. NitrItes are toxic at that level...but since there's no conversion...ammonia isn't being turned into nitrIte anyway. Like I said...a bit tricky. The tanks of yours that cycled must have had a pH level above 6...otherwise it's just not going to happen. When it gets low (but still above 6), it slows exponentially...but will still happen.

Yeah it's odd, but thinking back on it my other tank showed 6 ph through most of my 6 week cycle before. PWC's never got the NO2 & NO3 to a readable low, then one morning the nitrite was gone. My ammonia dropped quickly, like it currently is, so to be honest, the cycle isn't too different.

Everything got off to such a quick start that I thought it would be quicker this time, lol! Oh well, worth it in the end...
 
Crushed coral has been in for just over 24 hours. No change to ph as yet. What sort of timescale does it take on average to change ph & by how much is possible?

It's a 90L tank & I put about half a Kg into the tank in a bag made from a stocking. Do you think that is enough to make a difference?

Sorry for all the questions :)
 
tiguardo said:
Crushed coral has been in for just over 24 hours. No change to ph as yet. What sort of timescale does it take on average to change ph & by how much is possible?

It's a 90L tank & I put about half a Kg into the tank in a bag made from a stocking. Do you think that is enough to make a difference?

Sorry for all the questions :)

Normally it works very quickly...like minutes. Is it in the filter? You may want to take your hands and really rough it up a bit in the water to get some of the solids into the tank.

Sorry...I have no idea how much half a Kg is, haha. You can't overdose on the stuff though. It buffers and raises pH to a certain point then stops. The more the merrier, it won't hurt.
 
Just thinking out loud....

Looking back over this fishless cycle, my ph has always hovered between 5.5 & 6. My ammonia drops really fast & I have a nitrite reading of 3.3+ & a nitrate of 110+.

Does this mean nitrification must be/ have been happening for readings to get to these levels, even though I'm aware that It stops at under a ph of 6?

Looking back at my other cycles my ph has always sat at between 5.5 & 6, and I've always managed to get the cycle done. Maybe I'm just on the ph borderline??
 
Well, after 35 days, with a nice ph caused stall in the middle, I'm cycled!

Readings tonight are: Ammonia 0, Nitrite 0, Nitrate 20, ph 6.0.

Looks like that bit of buffering gave it the kick over the line it needed :)

Hmmm.. Why do these things always finish at a slightly inconvenient moment after all the waiting?

Going away for the weekend in the morning, back Sunday afternoon. Then away from Monday morning till late Thursday.

Do I (A) Do a big PWC on Sunday afternoon & move the stock from my other tank, or (B) get my girlfriend to feed with 1ml of ammonia every other day till I get back on Thursday to do a PWC?

Thanks for the advice from the members. Much appreciated.
 
tiguardo said:
Well, after 35 days, with a nice ph caused stall in the middle, I'm cycled!

Readings tonight are: Ammonia 0, Nitrite 0, Nitrate 20, ph 6.0.

Looks like that bit of buffering gave it the kick over the line it needed :)

Hmmm.. Why do these things always finish at a slightly inconvenient moment after all the waiting?

Going away for the weekend in the morning, back Sunday afternoon. Then away from Monday morning till late Thursday.

Do I (A) Do a big PWC on Sunday afternoon & move the stock from my other tank, or (B) get my girlfriend to feed with 1ml of ammonia every other day till I get back on Thursday to do a PWC?

Thanks for the advice from the members. Much appreciated.

Great news :)

Refresh my memory...are you just relocating your fish from one tank to another...or this one have a totally different stock while the other one stays up and running?
 
eco23 said:
Great news :)

Refresh my memory...are you just relocating your fish from one tank to another...or this one have a totally different stock while the other one stays up and running?

Hi Eco,

I'm relocating from my 60L to this 90L, then mothballing the 60 to use at a later date.
 
tiguardo said:
Hi Eco,

I'm relocating from my 60L to this 90L, then mothballing the 60 to use at a later date.

Oh dude...I coulda saved you some serious time, haha. You didn't need to do a fishless cycle :(. Since the bacteria adjusts to the fish...and the majority of the bacteria is in the filter media...all you've got to do is move every piece of filter media to the new tank, watch for / potentially deal with toxin spikes for a few days and it's done. Just think of this as more fishless cycling practice...and a way to become a more patient person :D

Here's the good news...go buy more fish :). You built a bio-filter more than capable of handling the fish you're moving over...so go crazy at the LFS if you want.

And yeah, if the cycle is done, move them over whenever you want. Just watch out for that low pH thing we've been talking about.
 
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