Currently, your tank and filtration sounds more than adequate.
In the long run, would be ok too tank size wise. Clown loaches can grow pretty big. They grow relatively slow and while they get up to a foot long, I've only ever seen that in wild caught CLs. Filtration wise I'm pretty certain you will be fine too. At the most, water changes MIGHT need to increase frequency/amount once they are much bigger.
Hope this helps!
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