PH wont stay down. Help
 

My tanks ph is 8.3 and my tap is the same... It has been tested by me a local fish shop AND petsmart and yes it is 8.3 so i bought some API proper Ph 7.0 and added some last night because i wanted to slowly drop the ph so not to shock the fish and I brung it down to about 7.6 in about 2 hours but this morning it was back up to 8.2 so I added a little more and dropped it down to 7.8 and i just cheched it again and its 8.2 again.... anybody know what is going on? does API proper ph just not work or what because it says it brings the ph to 7.0 and keeps it there but its not working for me....

i wouldnt use buffers to get the water to where you need for one they contain lots of phosphates (most do) and your ph will always swing. I would mix your water with reverse osmosis water to get it down. I would try 50/50 tap/r/o if your water ph is that high your hardness is probaly up there to.your fish will thank you.