Nice and speedy splash & go stones; I bought them to replace the Atomas for grinding & sharpening, as the Atomas can be quite harsh on plain carbon steel.
The stones don't need much water to stay wet (think a quick wash with the tap/a dip in water). The #400, in particular, is my favourite out of the 2. Of course, the #1000 is as effective as many online can attest to.
In longer sessions with the #400, do remember to check for flatness regularly. It can dish relatively quickly during heavy grinding e.g. resetting the bevels on a kiridashi.