If it were me I would either replace the broken front glass or buy a new/used tank and use the glass from this one for lids. I don't think it's worth the risk.
For silicone, I use GE window and door 100% silicone. Just make sure it doesn't say mildew resistant. Or you can use the stuff from lfs (a lot more expensive for the same product).
If it were me I would either replace the broken front glass or buy a new/used tank and use the glass from this one for lids. I don't think it's worth the risk.