I don't know, I've never tried it. I think a cleaning agent that doesn't foam would work.

The Dyson Submarine™ wet roller cleaner head has been engineered to clean effectively with just water. But if you decide to use detergent, please a choose gentle, low-foaming household anti-bacterial detergent. Do not use bleach or other harsh chemicals. Please follow the manufacturer's guidance on dilution for surface cleaning - and we’d advise against putting neat detergents in the clean water tank.

https://community.dyson.com/using-your...

Depending on which floors I mop (oiled parquet, tiles or epoxy resin floors), I add a super small amount of cleaning agent. This has always worked without any problems. But you should clean the container after use, as well as the mop roller.

Yes, I've already done that too. However, it shouldn't/shouldn't foam.