[ccol74]

My tap water has a PH of 7.4, but after it sits for a while the PH drops to around 6.2. I tested this theory by putting my tap water in a 5 gallon bucket and let it sit for 24 hours and the PH was the same as the PH in my tank which is 6.2. So I know it was nothing in my tank making the Ph drop. My current fish don't seem to mind the PH being that low but when I try to add fish they cant seem to take it, even after acclimating for an hour.

The tank has been set up for well over a year and this problem just has me baffled. What could be the possible cause of this problem and how could I fix it.

NH4 0
nitrite 0
nitrate 10

 

[remarkosmoc]

does your water go through a softner first and if so can you get non-softened water? Test your KH and GH. I don't know why it would come out of the tap high then drop but I would guess that you have a KH of 0 in the tank. This can be adjusted with baking soda using this calculator. I keep my cichlids around 12-15 degrees of hardness KH. Of course it depends on what species you are keeping.

http://dataguru.org/misc/aquarium/calKH.asp

 

[ccol74]

I tested the hardness of the water and the total hardness was about 12. I am keeping new world cichlids

 

[remarkosmoc]

is that 12 kh or gh?

 

[ccol74]

I found the total hardness, my understnding is that total hardness is a measure of Gh and Kh together. Individually I do not know the specific gh and kh values.

 

[remarkosmoc]

hmmm. KH is carbonate hardness, which is what your ph buffer, which is the one to be concerned with with regards to controlling ph. I would get the kit to test for that. I think that the api test you get at the big box stores includes both the gh and the kh test.

alternately, you could do the shotgun approach and treat without testing. You could put PH 7.0, .2, or whatever value you want in there, this puts in buffers and sets the ph for you, or you could by the buffer for what kinds of cichlids you have. Any of these products can quickly set ph and buffers up they way you need them. I prefer to measure and adjust with baking soda as it is much cheaper.

Here's a good article that explains why hardness is important when maintaining ph.

http://www.drhelm.com/aquarium/chemistry.html

 

[ccol74]

I will go pick up a test kit tomorrow and see what the specific values are.

 

[fumoffu]

Getting the KH up to a more stable level would be a good thing. But what also is going on here is a gas exchange into the water. The water coming out of the tap has less CO2 or O2 or something then the atmosphere. So when the two have balanced out it lowers the pH of the water since there is not KH to buffer. I am sure you could google a article to better explain it, but that is enough to get you started.