Mold growing on silicone...

[weaponsofmassdesign]

So I used GE Silicone 1 to build a sump, and now there is mold growing on it. It's not on the glass. It's only on the silicone. I thought this stuff was aquarium safe? Is there another reason it could be growing there?

 

[Lateral72]

Dumb question, but is the mold growing in the water or on the exposed parts?

If it's in the water, it's because the algae (not mold) is attracted to something in the silicone, or because it offers a good "footing" for the algae to hold on to vs. the glass. If it's above the waterline, it's growing mold because you bought the right stuff. You want to use silicone that does NOT have mold/mildew resistant chemicals in it. Because it's missing those chemicals, it'll probably grow mold in a humid/moldy area.

Adding a fan to the sump (if you don't have one already) will help keep the sump area drier, and help prevent mold. If you want to clean it off, use a papertowel and some vinegar.

 

[weaponsofmassdesign]

Well, it's growing below and above the water line. It's not very far above the water line and there is some splashing in that area. I don't have a light on the sump cause I'm not using it for a refugium. I don't have a fan on it, but I do have one I can add so I'll do that. I did clean it off. Looks like I got it all anyway. We'll see if it comes back. It smells like wet dirt if that helps. What would be the ill effects of this?

Here's a couple pics.

 

[weaponsofmassdesign]

Those pics are with the return pump off. The water flows over that baffle right to left, so that area is pretty much wet.

 

[Lateral72]

That juts looks like cyano/diatoms/etc. The reason it's likely sticking to the silicone only, is because the silicone offers a good footing for the algae to hang on to in the high current areas.

 

[weaponsofmassdesign]

Okay. I hope it's some kind of bacteria/algae. Thanks!