lower PH

inject pressureized CO2....works like a charm
 
peat filtration.
 
it's rarely a good idea to modify your pH or for that matter, your water chemistry in general. it's a far more complicated issue than just adding a cup of this or a spoonful of that.

unless you wish to breed fish species that require a specific chemistry range, the vast majority of fish in the hobby will do just fine in whatever chemistry comes out of your tap.

now to the point ... what's your ph, gH and kH and WHY do you want to change it.
 
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