This does seem to be a problem. I have yet to find a dechlorinator which removes chlorine, binds metals, 'detoxifies' the ammonia from chloramine, and does not contain a 'slime coat promoter'. The ones that don't contain something for the slime coat don't detoxify ammonia.
What we need is something that just detoxifies ammonia. Something that is only temporary, but by the time the effect wears off the filter bacteria have eaten all the chloramine ammonia, so not zeolite which permanently removes ammonia. But most brands of ammonia detoxifier also seem to remove chlorine so using one together with something like API Tap Water Conditioner (removes chlorine, binds metals only) would end up overdosing the chlorine remover.
If anyone knows of a product that just detoxifies ammonia and does nothing else, please let us know!
Those products which detoxify ammonia convert it to another form, but the effect wears off in 24 to 36 hours. This is fine where the only source of ammonia is chloramine in tap water because the bacteria in the tank will have 'eaten' this detoxified ammonia before it has chance to revert back to ammonia.
(Products that remove ammonia are not the same thing, and are not found in dechlorinators - they remove all the ammonia, and there is none left to feed the bacteria. Then they get full and stop absorbing ammonia and there are no bacteria to 'eat' the ammonia as they've all starved. Ammonia remover must be replaced before it becomes full - for ever)