my local waters ph is 7.5 from the tap and were i am located im right next to the filter station so my tap water is very clean (have been to the station and seen all chem readings) so it is great for water changes on most of my tanks. were i have a problem is i have one tank that needs a ph of 6.5 to 6.8. how do you guys drop the ph of your water for changes? i yoused ph down but i like to do water changes on my tanks every week so it will start to get pricey every 2nd or 3rd water change having to buy a bottle of it. is there anther way to drop the ph or are chemicals the only way how do you guys do it for fish that require the lower ph?