Unexpected pH reading after 80% WC

First, I'm new to fish keeping and the tank in question is still going through the nitrogen cycle. I understand that pH is not my main concern right now, but I like tracking test results, so I've been watching my pH through this whole process and am confused about my pH results today.

I set up a 10-gallon tank on Nov. 24th. The pH started at 7.8 (same as tap water) and, over the course of 2 weeks, went down to 7.4. I then did a 60% WC yesterday because my nitrites were off the chart and my nitrate had defaulted to 5. I did an 80% WC today because my nitrites were still off the chart (nitrates became measurable after the first WC, coming in at 60).

After the WC yesterday, my pH measured the same as the tap water (7.8), which was pretty expected. However, after today's WC, the pH measured 8.2. I don't understand how adding tap water of 7.8 to tank water of 7.8 can result in 8.2. I tested the tap water and tank water twice, just to make sure I hadn't done anything wrong.

I also tested tap water that had sat for 22 hours; it came in just slightly higher than directly from the tap--7.9 instead of 7.8 (based off the color being between 7.8 and 8.0 on the color chart). I use API Master Kit, and I always read the results in the same room, with the same lighting, against the same white background.

I did dose ammonia up to 4 after the WC, as my ammonia consistently drops to 0 well within 24 hours. Would dosing ammonia increase the pH?

 

That is interesting for sure. It has been discussed in a few threads that water parameters get pretty whacky when we run fishless cycles with a ton of ammonia.

I don't know anything in the cycle process that would raise your pH vs lower it as it used up your minerals. I however do not actually know everything.

Someone may come by here and just blurt out the answer from personal experience, but my first wonder is if you added any decorations or substrate since you are getting closer to ready to go get your new fish friends every day.

 

That is interesting for sure. It has been discussed in a few threads that water parameters get pretty whacky when we run fishless cycles with a ton of ammonia.

I don't know anything in the cycle process that would raise your pH vs lower it as it used up your minerals. I however do not actually know everything.

Someone may come by here and just blurt out the answer from personal experience, but my first wonder is if you added any decorations or substrate since you are getting closer to ready to go get your new fish friends every day.

No changes made from the initial setup other than removing two somewhat rotting betta bulbs a few days ago.

I had tested the pH prior to yesterday's WC and today's WC. The results were as follows:
Yesterday before WC: 7.4
Yesterday after WC: 7.8
Today before WC: 7.6
Today after WC: 8.2

(Where I said, "I don't understand how adding tap water of 7.8 to tank water of 7.8 can result in 8.2," in my original post, I was looking at the pH results from yesterday after the WC, forgetting today's results before WC showed it as 7.6.)

 

Which test kit do you use?

Liquid?

 

Which test kit do you use?

API Master Kit

Liquid?

Yes, the little bottles that you have to tip upside down and count the drops.

 

Ok, I had the same exact PH out of taps with the same problem. The gasses need to leave the water, it makes the test kit think its higher when its value is actually 7.8. Its not actually 8.2

 

Ok, I had the same exact PH out of taps with the same problem. The gasses need to leave the water, it makes the test kit think its higher when its value is actually 7.8. Its not actually 8.2

Okay, so I should just wait awhile and retest?

 

Ok, I had the same exact PH out of taps with the same problem. The gasses need to leave the water, it makes the test kit think its higher when its value is actually 7.8. Its not actually 8.2

I knew someone would know the answer to this right off the top . I think I had heard that but I've never tested quite that quick after a water change.

 

Okay, so I should just wait awhile and retest?

Put tap water in a cup straight out of the tap with nothing else in it. Let it sit for about 24 hours and retest

 

Put tap water in a cup straight out of the tap with nothing else in it. Let it sit for about 24 hours and retest

Okay, I will do that. (The bucket of water I let sit for 22 hours did have water conditioner in it.) So you're saying my tap water is likely not 7.8 or my tank water is likely not 8.2 after the WC?

My tank water has already gone down to 7.8. Thanks for the tip on the gasses!

 

My tank water has already gone down to 7.8. Thanks for the tip on the gasses!

Sure!