Ph 6.4

[carolandstella]

Hi can someone please help me i have a 180litre tank been running about 2 years without any problem.
my ph in the tank has always been 7.8 ammonia 0 nitrite 0 nitrate 0 for about the last 3 weeks my ph has suddenly gone to 6.4 nothing has been added to the tank at all i have 3 oscars and 1 pacu in there.I do 25% water change every 1 to 2 weeks then add with dechlorinated tap water only got plastic plants and gravel substrate which gets cleaned every time i do water changes
I also have 2 other tanks and the ph in them 2 are 7.8 when i do water change on them do the same add dechlorinated tap water Any suggestions would be much appreciated Carol

 

[minxfishy]

I cannot advise much on the ph, but I can say, you cannot house 3 oscars in 180L tank, you cant even have one Oscar in that size tank. The minimum size tank IMO is 75 gallon, 4ft long. Pretty sure the Pacu needs a larger tank too.

I know thats not what you want to hear, but in case you were not aware, I thought Id mention it.

 

[meguro]

Test your tap water for pH.

 

[indigoj]

Sounds like a ph crash - I've had this happen - test your tap water for Ph and Hardness (Kh) if the Kh is low then likely you've had a crash often due to 'old tank' syndrome, not enough water changes, adding things to the tank that can lower ph like some rock, substrates or wood.

It is incredibly unusual for you to have a zero reading for NitrAte - what test kit are you using (and is it liquid or test strips?)? - worth checking it is still in date or if it is strips then you need a liquid test kit to get accurate results. What dechlorinator do you use?

Also, to support what has been said, Oscars and Pacu get to over 12" (Pacu can be much larger.) A 180l tank is no where near big enough to house 1 of these fish for longer than a few weeks never mind all 4. With your water change regime I am inclined to think your test kit is fautly if it is showing no ammonia with a heavy bioload like that.