Silicone turning yellow? Help!

[BaileyB]

So I made my own sump a couple months ago, and recently (past couple days) noticed part of the silicone on one of my baffles is starting to turn yellow? Anyone have experience with this? Just wondering if it’s harmful. I used GE silicone 1 and I don’t dose anything to the tank except phytoplankton for my pods, the only things that are metal in the tank is the heater, and 2 pumps, don’t see any rust anywhere, I heard rust could cause it but haven’t found and definitive answers. What do you guys think?

 

[Peace River]

If you do a search on R2R you will find a number of related threads about silicone that has started turning yellow.

Although I have never heard a definitive answer for the cause, this is not the first time I have heard about aquarium sealant turning yellow for not obvious reason (e.g., dosing, treatment, bleach, incorrect silicon, etc.). If you do a search on aquarium silicon discoloring or aquarium silicon yellowing then you will get a number of results describing similar situations. IMO, keep an eye on it but not necessarily a reason for panic. Good luck!