Forward shower sump replacement

[ronmar]

I have a 93 350 Aft Cabin with a forward shower sump pump that died. I have a replacement but after removing the OEM sump I see that a hole was cut on the side and a nipple was installed for the drain tube which I assume is the A/C condensation line It's smaller than the cut out nipples supplied on the sump so that is why it was added. The nipple assembly is held on with a pressure nut similar to a thru hull fitting. My question is after I cut the hole in new sump what type of sealer recommended for the installation?

Secondly, I see a red hose that is not connected to anything lying along side of above. It appears to be dry for a long time and just lying there in the bilge area. I can't see where it runs to on the opposite end. Anyone know what it's for and should it be connected to something? There are no nipple cut outs opened on the OEM sump and the only lines connected are the shower drain, A/C drain, and discharge drain.

[Viper]

Any good marine sealant will do for the fitting. I'd probably use 3M 4200 or something similar. Is there a hot water heater in close proximity to the red hose? The drain hoses are typically directed into the bilge.

[ronmar]

Thanks. I will pick some 4200 up.
Funny you mentioned the water heater. I woke up this morning thinking I wonder if ran to water heater and was going to check this weekend. Sure appreciate to input.