Cycle Crash Catch-22? Fishless Cycle And Ph...

jessatiel

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Hello!

Today marks 6 weeks into my attempt to fishless cycle a new 20g tank. I’ve been watching ph carefully, lately, since I’ve heard ph can crash near the end of a cycle. When the ph gets near 6, I do a big (50%) water change. That brings the ph back up to 7-7.2.

However, I’ve had to do that pretty often, lately. Ph keeps dropping pretty quickly (last night was a little over 7, and it’s 6.6 this morning). Is this normal? I though get a big benefit of fishless cycling (besides not stressing fish) is avoiding lots of water changes.
Also, now some people are telling me **the WC** will crash the cycle!

How can I finish this cycle without crashing it?? Help!

Info:
-20g
-filter: penguin 150 bio wheel
-tap water ph: 7.8, and hard
-ammonia source: Dr Tim’s pure ammonia chloride
-substrate: mostly gravel, with special plant gravel around live plant roots
-plants: Java fern and S repens
-some resin aquarium decorations
-bubble stone is running
-temp is in low 80s, F (that’s as high as I can get it)

Cycle status: 6 wks and counting!
-2ppm ammonia drops to .25-.5 ppm in 24 hrs
-nitrites are super high, with no real signs of dropping. They are even high after WC.
-nitrates are high.

Thank you!
 
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jessatiel

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mgarza said:
No. I know there are lots of different opinions about this, but I’ve read lots saying that bottled BB can create an unstable system. I figured that going without bottled bacteria might be slow, but might be more stable in the long run (assuming I can ever actually finish the cycle!!)

I also unfortunately don’t have access to seeds g material from an established tank.

I’m reading both nitrites and nitrates, so I think the BB must be there... they just need to multiply, right?
 

mattgirl

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I've not experienced it but have read that the PH can fluctuate between day and night. By testing it at night and again in the morning it could be you are catching it at a bad time. Try testing it pretty close to the same time each day and see if you are still seeing a drop/rise.

You can add crushed coral and it should help stabilize it. I have personally done this and it works for me.

Water changes should not crash your cycle unless you forget to treat the water with a dechlorinator before adding it . Chlorine will kill the bacteria.

How long have you had high nitrites? Back when I did a fish in cycle in my 55 gallon tank my nitrites got up off the chart. At that point I was doing a big water change daily. The nitrite didn't change no matter how much water I changed. I did that 5 days in a row. I tested after the 5th water change and the nitrites were gone. They didn't go down gradually. They just dropped from off the chart to zero.

It sounds like you are very close to done. Since no lives are at stake in your tank you may want to just give it more time but water changes to get the nitrite/nitrates down may jump start it.
 

Mick Frost

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If Nitrites are above 5, they can stall your cycle. Have you tested your source water?
I use Seachem Stability on occasion, I've found it to ramp up the Nitrobacter side of the cycle faster (most of the time the Nitrite spike completes in less than a day, but that means most people never see it happen).
 

Fashooga

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A part of me wonders if your actually doing too much and not letting the tank cycle. Perhaps just let the tank do it's own thing and not touch it for a few weeks.

If your worried about pH I think you should look at getting a bag of crush coral and put a quarter cup to a half a cup of crush coral to help bring up the pH and stabilize it.
 

TexasGuppy

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Let your tap water set out for 24 hours and retest PH... I don't think Ph should be crashing that quickly after a water change. If it's going down to 6, you need Kh.
Water changes shouldn't crash your cycle unless you aren't keeping ammonia dosed to keep feeding the nitrites.
You've been cycling so long, and you ammonia is cycling so well, you probably have REALLY high nitrites. Some say this can stall the cycling, but in reality, I think it just takes forever to cycle this unnaturally high level. Do a 1 massive water change (90%) to bring it back down to 5 or less.. Add some baking SODA to get your PH to around 7.6 and redose ammonia.
You are probably going to need to get some SeaChem alkalinity buffer for long term maintance.. or crushed seashells in your filter.
 
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jessatiel

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Thank you for the help, everyone. Based on all these replies, I’m going to:
-let my tap water sit out for a day, and then test ph.
-move my parameter tests to evening, so my ph doesn’t seem artificially low because it is morning,
-add coral or baking soda to buffer the water.
-do one last big WC until nitrites are reasonable
-then let the dang tank sit and do its thing, undisturbed except for ammonia redosing, for a while.

Again — thanks for your time!
 

mattgirl

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jessatiel said:
Thank you for the help, everyone. Based on all these replies, I’m going to:
-let my tap water sit out for a day, and then test ph.
-move my parameter tests to evening, so my ph doesn’t seem artificially low because it is morning,
-add coral or baking soda to buffer the water.
-do one last big WC until nitrites are reasonable
-then let the dang tank sit and do its thing, undisturbed except for ammonia refusingredosing, for a while.

Again — thanks for your time!
Sounds like a plan

One thing I wanted to point out though. Baking soda is a quick fix and may not be necessary at this point in your cycle whereas the crushed coral works slower but keeps things stable and only has to be replenished as it very slowly dissolves over time. If I understand it correctly it actually raises the kh/gh (hardness) of the water thus keeping the PH stable. HTH
 

mgarza

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Best of luck to you!! And keep this in mind, it's easier to work with the water that you have instead of trying to get the water you want ( as in p.h. hardness ect)
 

TexasGuppy

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Bacteria.jpg

Nitrobacter doesn't grow very well below Ph 6.6 At optimal levels it takes almost twice as long as Nitrospira.

I know baking soda isn't ideal for maintenance, but for kick starting/finishing a cycle, I think it's fine.
 
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jessatiel

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Update:
Holy moly, I think the cycle is complete! 2ppm ammonia processed in 20 hrs. Another giant WC to reduce nitrates, and I think I’m ready for fish.

IMG_1732.JPG


The baking soda seems to have been key to keeping my ph up for the end of the cycle. I don’t think it’ll be a problem in the future, since my aged tap water has a ph of 7.6.

Thanks again for everyone’s help!
 
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