I admit I use tap water to clean the first sponge, the gunkiest one. Yeah, I probably lose a small percentage of beneficial bacteria but between the other sponges & HOB I'm sure it's safe.
I also use 2 sponges in my Aqua Clears & often rinse the bottom one in running tap.
I also use 2 sponges in my Aqua Clears & often rinse the bottom one in running tap.