Tap water for aquarium won't soften?

Stop trying, it shouldn't be necessary. Just use quality water conditioner like Amquel and Novaqua or Prime and you should be fine. They detoxify heavy metals and other toxic tap water additives.

A reverse osmosis filter would help, but again, it's probably unnecessary.

Note:boiling water does nothing to change hardness, don't bother with that suggestion.

hardness is not heavy metals In the water, you're getting some bogus information.

EDIT: using a house water softener is bad for fish, they substitute salt ions for some of the hardness and also contain harmful additives that are supposed to protect pipes, rather than actually softening the water. Eventually the salt and additives will build up in your tank and harm the fish. Normally the outside faucets aren't connected to the softener because the salt also kills plants. Only a deionozing filter will truly reduce hardness although a reverse osmosis will do some.

Again, the comment about boiling is pure crap.

Normally it's not necessary to adjust hardness or pH, most fish tanks will slowly settle to a lower pH on their own, and fish do better with a stable pH than a shifting one.

If you want to continue doing what you are doing, then store the water longer and use a different softening product along with the pH reducer. But again, it is not necessary.

1. Don't forget that pH scale is logarithmic, so a pH of 7 is ten times more acidic than pH 8. Such fluctuation is unhealthy for any fish, and quickly result in losses. Keeping fish in slightly more basic water then ideal is much less detrimental, though in the long run it's recommended to choose your fish based on your water parameters.

2. Of course you can't lower the pH just by pouring some goop into the water. If it was so simple everyone would be keeping Altum angels and samurai gouramis :P

The problem is that the water contains buffering agents so every time you pour some proper pH or ph minus to the water, these agents will bounce the pH back to normal. First you need to remove some of these buffering agents e.g. by adding some RO or distilled water. It's slightly more complicated than this, but there are many good articles about the topic and it's more than enough to understand why goops like that don't work.

3. Any decent dechlorinator removes harmful heavy metals too, so don't worry about that.

What is your Ph? That is the number you need to know. Chemicals to adjust hardness and ph are dangerouse for fish and don't work very well anyway. If they do work, you end up with bouncing ph, which can kill your fish.

You can try adding drift wood.

But you are better off just sticking to fish that thrive at the ph that you have. Most fish can adjust if carefully acclimated, to a ph outside of there ideal range. Avoid more sensitive fish, which often includes wildcaought fish, that may not adopt to your ph.

why not try to remove the hardness by boiling the water first, and let it cool overnight? sure it needs more time, but it will pay by not risking your kidney or gallbladder

Lewis can u answer my newest question plz