Hmmm, is it more seaweedy, or like an eggy sulphur smell? I find seaweedy smells tend to come with more algae, and eggy smells with lots of decaying organics - both could be happening here!
Almost certainly IMO it's just that disturbing the submerse plant roots has also disturbed the waste products of some anerobic bacteria colonies that were doing their thing. Don't worry about the smell affecting the fish, you may see many alarmist posts on various forums claiming the sulphuric chemicals are harmful to the tank inhabitants - but they arent at all in the water column due to the oxygen present. For the sulphuric compounds to be toxic in the water column, oxygen would have to be below equilibrium level to the point the fish would already be visibly suffering badly, you should be totally safe from that with your setup due to the high water circulation
. Every time I've had a "dirted" tank, a large fish eventually digs up the substrate and the dirt ends up being mixed with the sand/gravel
. Other than making things look messy, and maybe a
temporary smell, it's nothing to worry about.
As it's a hillstream loach tank, just try to maximise oxygen levels - keeping the tank at the lowest temperature comfortable for the inhabitants (I wouldent bother wth a heater for any of your species), increasing surface movement (as much as the floating plants can tolerate) and doing water changes to remove dissolved orgainc carbons as often as convenient. If your not really worried and everything seems fine apart from the smell, or are fed up doing water changes just for a smell, you could add a bag of cheap carbon to the filter every week, or Purigen/Polyfilter are even better but less cost effective options.
Don't worry, the smell will go away soon!
Btw, do you have any Malaysian trumpet snails or any burrowing snails in this tank? If not, I would reccomend some too
.
. Other than making things look messy, and maybe a