My tank, at its peak, had 9 cardinal tetras, 4 hatchets, 4 cories, 4 ottos, and a talking catfish (Agamyxis pectinifrons
). A picture of my 30 gallon setup is in my gallery.
I'm not sure if you are referring to new fish or the fish already in the tank, so I'll answer both.
For fish already there: When I first started my tank, the catfish was the only one in there and the pH was neutral. At every water change, I changed about 20% of the water (5 gallons) with store bought ro
water. There are additives I needed to add, like Electro-right and tetra's BlackWater Extract, but the water I was adding was very soft and acidic. Adding the water like this slowly changed the parameters to what I needed and did not adversely affect the fish's health.
For new fish: Since the fish are most likely coming from a lfs
with a different pH, the most effective way to acclimate them to your tank is the drip method sw
enthusiasts use. Put the fish and the original water in a bucket (I used a fish bowl I set aside just for this purpose). Run an air line from the tank to the bucket. Tie a very loose knot in the line, and siphon tank water into the bucket. Pull the knot tighter until the water slowly drips into the bucket, about a drop or two a second. When the volume of the water in the bucket doubles, carefully net the fish out of the bucket and place them in the tank. They will be fine this way.