Low PH during 2nd stage of cycle

[Arnoniko]

Hi,

I am 3.5 weeks after starting a 25G tank with 2 molies & 2 swordtails. I figured this would be a light load to start a cycle with fish. I used Microbelift special blend to speed up the cycle. During the first 10 days I had high amonia & the swordtails were stressed. The female even has a pop-eye. However with daily PWC & switch to Seachem prime the amonia stablized & the fish seem to be healthy & active.

At the second stage of the cycle I did several things:
1. Lowered PH to 7 with seachem PH buffer since the tap water PH is high (7.8)
2. Start using Kordon Amquel plus to detoxify tap water amonia (0.25-0.5 ppm) when doing PWC & reduce nitrite levels when they spike.
3. Use Seachem stability daily per instructions to boost the cycle.

Over the past week I think I must have done 3-4 15% PWC's including a 25% PWC this morning.

During this week I noticed that the PH level drops to 6! After a 25% PWC, with no PH adjustment, the PH was 7.4 after 15 minutes; PH7 after 2-3 hours & after 2 more hours - PH6.... I am using the API test kit.

Amonia is low & nitrite is gradually increasing. The fish are healthy & active & do not show signs of oxygen shortage (they don't stay near the top to gasp for air). The reason I continue to do the PWC is because I am concerned that the low PH will slow down the 2nd stage cycle & possibly cause irritation if left unchanged for more than 2 days.

I don't understand why the PH decreases so fast. Today I added some shells to build a low PH buffer. Is this normal during a cycle? Any advice is very much appreciated.

 

[Crepe]

I wouldn't have messed with your pH with chemicals...And yes, pH swings are very normal with cycling. Just wait it out and see what your final levels are.What substrate are you using? My substrate buffers my ph to 6.8-7.0
My water comes out 7.6-8ph and I don't really have any problems (when I didn't use the buffering substrate) so it isn't really much of a problem anyways.

I'd also take a peek at your kH...that's essentially your water's buffering capability.

 

[Arnoniko]

I have a substrate that should not affect the PH. Don't remember the brand but I made sure it's PH safe. Also - PH was high (around 8) in the first 2 weeks. This was the reason for the chemical intervantion...
KH - I believe the water in my area are slightly heavy. I don't have specific numbers

The Amquel plus reads the "generally it does not affect PH". Could that be the reason?

 

[Crepe]

Water conditioner will not affect ph...Just wait it out until you're done cycling. Don't mess with the ph anymore. You want a baseline first before you do any modifications.

 

[ejaramillo01]

+ 1 to Crepe

I don't know if the Amquel plus has an effect in pH.

But I do agree that the use of chemicals to reduce ammonia, nitrites, or nitrates is not a good situation. These products definitely have an effect in the cycle, and some times are not even good for your fish, I know that you are trying to reduce ammonia or nitrites, but the best and safest way to do it is with partial water changes, as many as needed to maintain good water quality.

Also don't worry about pH right now, the fish that you have will adapt and be happy in a "stable" pH, even as high as you cited. But your fish will suffer more to swings in the pH and they could die as a result of the yo-yo effect of the pH.

Keep up with your PWC and you will be fine.

 

[Arnoniko]

Thank for your advice! I will keep away from Amquel & Ph buffers.
It looks like the cycle was reset as my amonia is up (1ppm).
I think there are 2 things that could have caused this:
1. low PH killed the bacteria?
2. changed filter in parallel (kept old filter together with new filter for 2-3 days) - could it be that this reduced the capacity of the biological filter so much? What about the bio wheel? most of the cacteria are supposed to be on the wheel no?
Any ideas?
Thanks!!!