PH Kit from Fluval Reading Very Acidic

[Jessie]

New Fluval test kit has PH reading 5.5-6! As did my tap water and bottled water. I exchanged it for a new one today thinking it was faulty. Aquarium store also tested their water and got same results as mine. Tried again. Same results. Local city water tests at 7.2 to 7.8. My research says chlorine can throw off results? What is going on with this reagent? Any ideas? 
 

First pic is first test. 
Second pic is new kit with aquarium water on left and tap water on right.

[Ruud]

Hi @Jessie , did you check if there is an expiry date on the packaging? If its from an old batch it could give incorrect parameters. Thats the only thing I can think off right now. 

[Jessie]

It had an expiration date of 2024. I replaced it and still got the same results. Weird hey? 😐

[be28ans]

That is very wired, i even tried looking on the internet . 

[Jessie]

Took my tap and tank water with new PH bottle back to aquarium store. API tested my tank at 6.8. 
Again they tested their water with my Fluval PH and was reading at 5.5. Everyone is stumped. 
4 of the 6 shrimp I put in yesterday are dead. What on earth is going on? Ugh! 

[LaurieinIA]

I’m having similar trouble with test results. 

Not long ago, I needed to replace testing supplies and I changed from the Fluval test kit to API one. I did this because I could never confidently read the Fluval results - esp nitrates.  I wasn’t too concerned about not reading the pH as my only tank at the time was African cichlids... as long as it got past greenish yellow, I accepted it as high enough.

I still have the Fluval pH test (the others have run out) with a result of 7.0, maybe 7.5, and my API test shows a solid 8.0.  This is in a community of tetras, so the difference could/should be a problem.  They seem fine overall, but I have lost a few within a couple days of adding them, so I’m wondering more if my pH is really 8.0.

I don’t know which test to trust and if the readings are that different on pH, can I trust the other test readings?

I’ve talked to my LFS and they don’t have a great opinion of the API tests.  They don’t even sell them.  Of course, they are willing to test my water (which I will have them do later this week), but it still doesn’t give me the answers I need at home.  I’ve tried tetra test strips in the past and have the COOP ones as well... I can’t confidently read those either.