Need advice, not so slow leak in sump

[gregzz4]

Not sure I can help but can you post a clear pic of the suspected leaking area ?

[trilinearmipmap]

Suggestions:

1. Assuming you have an auto-topoff, measure the salinity decrease to calculate the volume of your leak

2. Orca underwater glue (available at J & L) is supposed to glue and seal underwater. I don't know how well it works, I keep a tube on hand

3. If it were me I would temporarily re-plumb to a rubbermaid or similar sump then take the sump out and either repair it properly or replace it

4. Not knowing the layout of your sump, you could even (temporarily) put a mini-sump inside your sump (ie. a bucket just big enough for the drain hoses to go into and to house a return pump) if you are worried about the leak worsening overnight

Best of luck