Originally Posted by br0kenmentat
would it negate the effects of the driftwood on my ph at least? my water really is more like 6 i also cant use buffer cuz of plants
Would try a quarter to a half cup of coral per 20 gallons of water in a nylon bag stuffed into the filter.You will need to ocasionally clean the coral under tapwater for it will become covered over time with silt,mulm,bacteria,and or algae and thus become less effective or you can replace it when this happens and you observe the pH starting to fall.
I might want a second opinion on pH levels especially if strip style test is being used. I would test the pH with test kit such as API Freshwater Master kit that uses drops of liquid and test type tubes. This kit is far more accurate and could be your pH is not as low as you might think.
It takes quite a bit of driftwood to affect the pH because with each weekly water change,you will be adding water with usually a pH level a bit higher than that which is measured in the tank.The breakdown of organics in the aquarium over time ,does tend to cause acidic conditions and pH will lower but with regular water changes assuming the tapwater has more buffering capabilities,,this is seldom a need for worry.
In any event,the crushed coral added to the filter should increase the hardness a bit and prevent the pH from falling further while not causing too much stress for the fish. Would begin with 1/4 cup per 20 gallons and wait a couple three days before adding more if needed.