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Can you put uncured pure Silicone in an aquarium???

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Magnum Man

Fish Herder
Jun 21, 2023
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Southern MN
I've been fighting suction cups on just about everything in several of my tanks... a little www. reading, sounds like lots are converting equipment that uses suction cups, over to magnets...
while I was www. reading, I thought I came across someone putting a dab of silicone in the hollow part of the suction cup & then pressing it on the side glass of the aquarium... I think they were implying doing that to a full aquarium... pretty much all of my new heaters use suction cups, & none of them ( several brands ) will stay on the glass fully, between my weekly water changes... I think this might actually work... just wondering if anyone has tried it???
The glass needs to be dry before the silicon is applied and must remain dry for at least 24 hours before being covered in water.

Aquarium heats don't need to be held in place. I gave up using suction cups and heater holders because they were crap and stopped holding anything after 6 months. I just let my heater sit in the aquariums on a 45 degree angle and the bottom of the heater rested on the substrate. The heater cable (cord) was bent slightly over the edge of the tank and the heater didn't go anywhere.
I was personally thinking it would be like adding a silicone food grade grease to the suction cup, which I've done before ( not in an aquarium ) but the grease in those circumstances displaced all the air in the cup more easily, & keeps the water from coming in & helps hold the cups on... thinking an inert (aquarium safe ) replacement might be silicone... it doesn't need to harden & stick the cup to the glass... it just helps keep the water out, so the cup continues to stick like it did when 1st placed on the glass... if no one has tried this, I may have to be the Guinea pig... to see it it works like silicone grease
I actually drop all suction cups for all devices into recycling, straight from the package. They suck. Or they don't suck. Something like that.

I don't use them, because they'll fail. I just do what Colin does, place any heater I use strategically.
on the heaters, right now I'm running the cords under my hang on tank plant house plant pots & putting the heaters under them, which is in the bubble stream from my 10" air bars for circulation of the water around both the heaters & the plant roots
My suction cups for my sponge filter are also a mess, but I’ve use suction cups for my heater and they work brilliantly.
Not all can do my solution for my heater as I run under gravel filtration. I just used plastic wire ties to attach the heater to the air risers. If there is suitable hard scape such as spider wood the same thing could be done.

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