Thats a misunderstanding on whats going on. One thats often circulated.
The nitrogen cycle needs alkalinity. This has a different meaning to "a ph above 7" which would be better called basic rather than alkaline to avoid confusion with alkalinity. Alkalinity is a measure of some disolved solids in the water and is mostly made up of carbonate hardness (KH) and they are generally considered to be the same thing. The API KH test is actually a test for alkalinity for instance. There is a link in that water with low pH usually has low alkalinity, but acidic water will still have some.
Many people keep fish in low pH conditions, they cycle their tanks just fine. I wouldnt worry about a pH of 6.8.
One thing to be aware of is KH is what gives your water the ability to absorb acid, so the more KH you have the more stable your pH will be. If your pH drops a significant amount suddenly its a sign your KH/ alkalinity is low also, and the nitrogen cycle will no longer be able oxidise ammonia. If you test tomorrow and its dropped to low 6s you might want to investigate further the cause and possibly look at what your KH is. If you are worried about it though, get some crushed coral in a media bag or some cuttlefish bone and put it in your filter. This will be a steady source of calcium carbonate which will keep your general hardness (GH) and KH at a steady level and stabilise your pH.
The nitrogen cycle needs alkalinity. This has a different meaning to "a ph above 7" which would be better called basic rather than alkaline to avoid confusion with alkalinity. Alkalinity is a measure of some disolved solids in the water and is mostly made up of carbonate hardness (KH) and they are generally considered to be the same thing. The API KH test is actually a test for alkalinity for instance. There is a link in that water with low pH usually has low alkalinity, but acidic water will still have some.
Many people keep fish in low pH conditions, they cycle their tanks just fine. I wouldnt worry about a pH of 6.8.
One thing to be aware of is KH is what gives your water the ability to absorb acid, so the more KH you have the more stable your pH will be. If your pH drops a significant amount suddenly its a sign your KH/ alkalinity is low also, and the nitrogen cycle will no longer be able oxidise ammonia. If you test tomorrow and its dropped to low 6s you might want to investigate further the cause and possibly look at what your KH is. If you are worried about it though, get some crushed coral in a media bag or some cuttlefish bone and put it in your filter. This will be a steady source of calcium carbonate which will keep your general hardness (GH) and KH at a steady level and stabilise your pH.
ph has been stable since the last time. Am. Drops to zero with 2ppm dose but nitrites and nitrates are constant. I tried the nitrate solution with a smaller long established tank and it reactes as one would expect. However with the cycling tank when I add the first bottle it turns a brown colour that remains constant even after adding 2 nd bottle with instructions followed. Sorry but any insight? Not finding much online
