API Tap Water Conditioner - In Praise Of

I agree wholeheartedly. I have been using this product for several years, and would not change to another. It contains only 2 chemicals; one to remove chlorine and one to bind metals.

As noted by fcmf, the 30 ml (1 fl oz) bottle has a dropper in the lid which makes it very easy to dose small volumes of water such as a bucketful. The larger bottles have measuring cup lids. I too have a 30 ml bottle which I refill from a larger bottle.
A couple of words of caution about the really big bottles. They may be cheaper pro rata than the smaller bottles but unless you have an enormous tank, you'll only get half way through before it reaches the use by date. The 473 bottle I bought a couple of years ago is still over half full and expires in November next year. And the 473 ml bottle I have is more concentrated than the smaller bottles (1 ml treats more litres) so I had a complicated calculation to work out how many litres I should treat with 2 drops. Unless you have a 500+ litre tank, stick to the smaller sizes!