I dont know what to do anymore

Question
I have 1 gallon, 5 gallon, 10 gallon and 25 gallon aquariums (1 of each). I can't seem to get a straight answer from anyone, pet stores say to maintain your tank and check the parameters weekly, so I did. Other hobbyists have said that I am causing the excessive fish deaths that way and to maintain my 25 gallon tank less frequently like once or twice a month, so I did. An aquatic store employee suggested that real plants would help, so I bought them and installed them in my 25 gallon, they didn't help, so I removed some, that didn't help so I put them back. The water parameters in my 3 smaller aquariums are awful yet the fish are healthy. I haven't had any deaths in the 1 or 10 gallon. I use the 5 as my hospital tank, so I've had a few there, but nothing I didn't expect. I was told to try Amquel+ or Ammolock as I had some minor ammonia issues. That didn't work. I have a PH problem, my municipal supply is awful PH 7.6-8.6, ammonia .5 ppm. PH Down doesn't change anything in the doses recommended. I am so sick of fishing out dead fish every time I turn around. This is getting expensive and ridiculous. I have tried everything that I have had suggested and nothing is working. At this point I am ready to try to sell the fish back to the pet store and throw away all the aquariums and supplies. I am extremely frustrated and I think that this is ridiculous. I did everything by the literature to begin with. I am grasping at straws and have had enough. Can you suggest something to stop my fish from dying? The sooner the better as my 25 only has 3 black skirt tetras, 2 danios, 2 guppies and 1 giant danio (I think). Thanks in advance for taking the time to read my rant.

Answer
Well, lets see if we can make some progress here.
First off, forget the PH for the moment. You can do a couple of things, one RO water or springwater or you can get fish that will do well in the water that you have.
Africans, Rainbow fish, Mollies  and lots more.
Buffers only mask the issue and don;t really change the ph in order to do that you have to actually alter the chemical composition of the water.
RO will do that and make some good drinking water as well.
The tetras will not do so well in that water, danios and guppies will be ok but not really as tank mates, the danios being a bit too active for the guppies.
Stop all the additives and quick cures for now and do any of the above actions, RO-Springwater or Fish specific top your water conditions.
If you need assistance choosing fish or hardware feel free to ask.
Don;t give up, the only way you really lose is if you quit.


I would use spring water out of the ground, I don;t know where you are from but I am in the Adirondacks, we have springs all over the place. If you have some near you the water quality is usually very good.
You can use bottled water, but at that level you may consider the RO unit.
If you need anything, just ask.