PH and cycling

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DodgeRT

Aquarium Advice Activist
Joined
Jan 6, 2005
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Will the PH fluctuate during fishless cycling? I am on day 2 of the cycle and my PH is 8.4. Im worried this is too high. Should I do anything about it now or just let it ride?

What really cooks my noodle is that my tap (well) water registers 6.6.
 
I am currently in about 2 weeks of a fishless cycle and have not seen my PH fluctuate yet. It stays steady at 7.6.

What is your KH? As it is my understanding that this is a signifigant factor in PH fluctuation.

By the way, my fishless cycle consists of dead shrimp purchased at the grocery store. How are you fishless cycling your tank?
 
I am using pure ammonia and tank seed from a friend to cycle.

I have not measured KH.
 
First off, you may have a higher pH tap water than you think. If it is coming out of the tap with high levels of dissolved CO2 (common) then this acid will give you a lower pH reading than after the water has sat overnight and the CO2 outgased. Do that experiment, testing right out of the tap and then testing aged water to be sure whether the pH in the tank is true or if there is a buffering agent in the tank driving up pH.

If you still get the identical pH out of the tap, then you'll need to see what in the tank is the cause, like the substrate, rocks, shells, coral, anything calciferous.

If you want to keep Africans or livebearers you are golden with a pH of 8.4 - I'd not worry a bit about it. If you have other plans, you might be fine anyway because most commonly available aquarium fish are farm raised in harder, more alkaline water than what they originally came from in the wild, so they are remarkably adaptable. See what the pH is at the closest LFS to you, or see what other fishkeepers in your area are stocking their tanks with.

To (hopefully) answer your question, there is nothing in the cycling of a fish tank that will change the pH, assuming you are doing nothing but running your filter, heating the previously dechlorinated water, and adding ammonia every day.
 
Thanks TG, that helps a lot. I will check everything again when I get home and let you know what I find. You are right about the PH though. When I first checked it (6.6) it was right out of the tap, the 2nd time I checked it (8.4) was after it had set overnight.
 
To (hopefully) answer your question, there is nothing in the cycling of a fish tank that will change the pH, assuming you are doing nothing but running your filter, heating the previously dechlorinated water, and adding ammonia every day.
Unless for some reason nitrates sky rocket, but your pH would go down :wink:

What fish are you planning on?
 
Try testing the ammonia your adding ;) I bet that has really high PH.

OH BTW adding PH down will help your cycle just thought id let your know that the bacteria like the stuff in PH down. phosphate??

Phosphates: All species of nitrifying bacteria require a number of micronutrients. Most important among these is the need for phosphorus for ATP (Adenosine Tri-Phosphate) production. The conversion of ATP provides energy for cellular functions. Phosphorus is normally available to cells in the form of phosphates (PO4). Nitrobacter, especially, is unable to oxidize nitrite to nitrate in the absence of phosphates. ( ph Down is phosphoric acid)

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

The optimum pH range for Nitrobacter is between 7.3-7.5

Temperature 72-88F. The temperature for optimum growth of nitrifying bacteria is between 77-86° F (25-30° C).
 
Try testing the ammonia your adding I bet that has really high PH.
It's the tap water. Nothing is changing the pH once the water is in the tank except for the equilibration of the gases already in the tap water.
 
Menagerie said:
It's the tap water. Nothing is changing the pH once the water is in the tank except for the equilibration of the gases already in the tap water.

But its not a bad thing? I mean everything seems normal, so if my PH continues to hover 8.4 thats ok?
 
But its not a bad thing? I mean everything seems normal, so if my PH continues to hover 8.4 thats ok?
Absolutely. The pH is what it is. If it goes up from there, then there's a problem. If you are planning on keeping cichlids from Lake Tang or Malawi, your water is already to their liking.
 
bottled ammonia contains a PH of 10-12 or so and yes adding it to a tank can slightly change PH over time.
 
pH

My pH was highest in 8.4, too, when cycling th efirst week. When nitrite started to form it dropped back to 7.8-8, which is the tap water ph.
 
When I fishless cycled i introduced seeded material 3 times. I also changed water a few times. My cycle lasted 10-12 days. PH seemed to rise also during the cycle. heres my notes and test results day by day.

Set up tank. seeded with gravel, filter, rocks, 50% tank water.

10 gallon tank

9th Tested 0 ppm ammonia 0 ppm nitrite 0 ppm nitrate 7.4 ph Temp 86-88F
(added Bio-zyme)(added a pinch of flake food)

10th Tested 0 ppm ammonia 0 ppm nitrite 0 ppm nitrate 7.4 ph Temp 88-90F
(water change )(ph down)


Started adding Ammonia.

11th Tested 5-6 ppm ammonia 0 ppm nitrite 0 ppm nitrate 7.6 ph Temp 88-90F
(added ammonia TOO! MUCH!! get ammonias to 5-6 ppm)(water change)(ph down)

12th Tested 3-5 ppm ammonia 0 ppm nitrite 0 ppm nitrate 7.8 ph Temp 88-90F
(water change)

13th Tested 3-5 ppm ammonia 0 ppm nitrite 5 ppm nitrate 7.6 ph Temp 88-90F
(water change with seeded tank water and gravel wastes)
(added gravel, rock and air bubbler)
(added Bio-Zyme)

14th Tested 3-5 ppm ammonia 0 ppm nitrite 5 ppm nitrate 7.8 ph Temp 88-90F
(added ammonia about 7-8 drops)

15th Tested 6 ppm ammonia 0,25-0.50 ppm nitrite 10 ppm nitrate 8.0 ph Temp 88-90F
(added ammonia 6-7 drops )(added clean water)(lowered temp)(added Bio-Zyme)

16th Tested 5-6 ppm ammonia 0.50 ppm nitrite 10-20 ppm nitrate 7.8 ph Temp 84-86F
(added ammonia 3-4 drops)

17th Tested 2-3 ppm ammonia 0.50-1.0 ppm nitrite 10-20 ppm nitrate 7.8 ph Temp 84-86F
(added ammonia 3 drops)(added ph down to 7.4 ph)
(seeded with filter pad rinse)

18th Tested 1 ppm ammonia 0.50-1.0 ppm nitrite 20 ppm nitrate 7.4 ph Temp 82-84F
(added ammonia 3 drops)( Lowered temp 82-84F)

19th Tested 0 ppm ammonia less than 0.25 ppm nitrite 20-40 ppm nitrate 7.4 ph Temp 82-84F
(added ammonia 3 drops)

20th Tested 0 ppm ammonia 0 ppm nitrite 10-20 ppm nitrate 7.4 ph Temp 84F
(added 1 drop every 4 hours, 2 drops before going to bed)
(topped off with clean water)

cycled! changed 50% of the water , lowered temp to 78F and added 6 fish. no problems
 
Some of you know this, but I'll throw my 2 cents in here. My fishless cycling was going great until during weeks 3-4 the pH dropped from 7.0 to 6.0. At that time, the nitrites and nitrates were increasing, indicating the cycle was working. Then, the cycled stopped and has yet to start up again as of week 5. Needless to say, "something" happened and now it seems my bacteria have died off. The ammonia, nitrite, and nitrate levels haven't budged in a week, and even a PWC did nothing.
So, I hope things go better for you with your cycle.
 
Thats sucks Ive never had a problem fishless cycling yet. Every time it takes about 2 weeks max. I guess I am doing something right or am just lucky ;)
 
I guess everything is ok.

Day 3
Temp: 80
PH: 8.0
NH3: 5ppm
NO2: 0ppm
NO3: 0ppm
 
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