I do wonder if they are a bit hot, being so close to the lights. The downside of a Juwel tank is that the water level has to be quite high for the filter so this brings them within inches of the powerful lights.
OTOH, you don't get an unsightly water line.
I'm running a juwel tank as well. On water change day I take out a handful and chuck it out, usually take the ones with leaf damage.