Hello, the pH of my tap water is always 7.8 and it has never changed. I have tested it again today and still 7.8. However, the water in my new tank (which has finished cycling so I'm pretty sure it's not that) dropped to 6.0 (or it may be lower, just 6.0 is as low as the API Liquid Test Kit will read). Therefore, I did a 25% PWC and the pH is now up to about 7.4 and I will be testing daily until I'm sure it's good again. But why would this happen? The water in my other tanks remain at the normal 7.8 so I'm very confused. See the question/answers below:
1. Size of tank?
2. Water parameters
a. Ammonia? 0ppm
b. Nitrite? 0ppm
c. Nitrate? 10ppm
d. pH, KH and GH? pH was 6.0 or less now after 25% water change 7.4. KH 120ppm GH 75ppm
e. Test kit? API Liquid Test Kit
3. Temperature? 79° F (26° C)
4. FW (fresh water) or BW (brackish)? FW
5. How long the aquarium has been set up? Just over 1 month - it is cycled.
6. What fish do you have? How many are in your tank? How big are they? How long have you had them?
1x bristlenose pleco (about 2")
4x neon tetra (very small young ones less than 1")
2x platy (1.5")
4x zebra danio (1.5")
7. Were the fish placed under quarantine period (minus the first batch from the point wherein the tank is ready to accommodate the inhabitants)? Yes
8. a. Any live plants? Fake plants? Live plants (been there a while, unlikely the problem and silk plants)
b. Sand, gravel, barebottom? Gravel
c. Rocks, woods, fancy decors? Any hollow decors? Just the plants
9. a. Filtration? Yes
b. Heater? Yes
10. a. Lighting schedule? What lights are used? Fluorescent Full Spectrum 12hrs/day
b. Any sunlight exposure? How long? Just what comes in the window
11. a. Water change schedule? Weekly
b. Volume of water changed? 25%
c. Well water, tap water, RO water? Tap Water
d. Water conditioner used? Seachem Prime
e. Frequency of gravel/sand (if any) vacuumed? The very top, gently to not disturb live plants
12. Foods? Tetra Colour Flakes alternating with Nutrafin Staple Food
How often are they fed? Once a day
13. a. Any abnormal signs/symptoms? 3 platies dyed, all other fish (including 2 other platies) are totally fine
b. Appearance of poop? Normal
c. Appearance of gills? Can't see a lot of them but all seems okay
14. a. Have you treated your fish ahead of diagnosis? No
b. What meds were used?
***Like I mentioned my other tanks are fine, and my tap water has not changed. Thanks for all help.