The xenia doesn't need high flow, so if its in direct flow then maybe move it off the the side of the path of flow.
The clown... hmmm I don't if she will lay without a mate... but I suppose its possible, never seen it though. If it does, take the rock out and scrub the eggs off with a brush or scrape it with something, then give it a good rinsing with salt water (not fresh don't want to kill off your BB or anything else by using fresh water). You can probably wait a few days to do this, as she mite eat the eggs if they go unfertalized, but if she doesn't eat them they will eventually rot, and could indeed cause a spike. You could always provoke her into eating them by putting your hand near the eggs, or a feeder stick or something and that mite make her eat them. But no I still wouldn't recomend getting a second one untill upgrading.
The clown... hmmm I don't if she will lay without a mate... but I suppose its possible, never seen it though. If it does, take the rock out and scrub the eggs off with a brush or scrape it with something, then give it a good rinsing with salt water (not fresh don't want to kill off your BB or anything else by using fresh water). You can probably wait a few days to do this, as she mite eat the eggs if they go unfertalized, but if she doesn't eat them they will eventually rot, and could indeed cause a spike. You could always provoke her into eating them by putting your hand near the eggs, or a feeder stick or something and that mite make her eat them. But no I still wouldn't recomend getting a second one untill upgrading.