Ive had a 60in x 18in x18in community fresh water tank for 15 years and been very happy with it. No problems except the odd ancient fish dying. Even my Khuli loaches used to breed.
In January this year I got a new carpet and had to move my tank, so I decided to change the set up of the tank. I bought a huge gorgeous piece of bog wood about 36in long x 12in x 12in. I soaked the bog wood and refreshed the water over a two week period. I then reset up my tank using about a third of my old water, same gravel, new external filter but old filter mediums. My fish looked fine but I started to lose the odd one, when I tested the water my PH had dropped to 5. I added approx 2 to 3 kg of coral sand over a week long period and this raised my PH to 7. But when I checked my KH it is only 3. I waited and it has not raised so I put 3 bits of ocean rock (about 5in long) in. This has not helped. I have also added some Aquarium salt about 6 tablespoons.
My PH 7, No ammonia, No nitrate, No nitrite, GH 12, KH 3.
My tap water is med/hard and KH is 3 too, I had never tested my tapwater in the past but I have never had any problems in the past
Ive lost about 20 fish now and most of my plants have died.
It would be a really difficult job to remove the bog wood but I will if I have to. But this still leaves my tap water as KH 3.
Although I wish to resolve this asap, I dont really want to resort to adding chemicals on a regular basis, I would prefer to combat this naturally and prefrably keep the bog wood.
Any Advice? Thanks.