Siliconing overflow to established tank?

[Powder Blue107]

Like the title says, I plan to install (silicone) an overflow to my established tank. Its been up for about 7 weeks now. Not sure if it matters but ill say it anyway. I have 2 clowns, 12 crabs, peppermint shrimp, 2 corals ( xenia and evergreen). My questions are as follows:

Can i lower my water level (2 inches below bottom of overflow) and silicone it with inhabitants in the tank?

If i avoid getting actual silicone in the water, will the fumes alone contaminate the water?

If the fumes will contaminate my water will lowering the water level, covering the water and taping around the bag to seal it from outside air harm any beneficial bacteria?

Which silicone should i use? I was thinking GE 1 Door and window 100% silicone aquarium safe ( No anti mold of bacterial ) im sure. Just double checking. Preferably something that doesnt yellow after application. Im open to opinions.

How long should i wait for it to cure for me to fill tank back up without harming my fish?



Thanks in advance to anyone that helps.

 

[clevername]

i did this, even drilled the tank with water in it.

Read up on silicone, it just releases Low ph gas... it cures under water too

 

[Timfish]

RTV 108 is twice as strong as the generic silicone available at home improvement stores. You'll probably have to get it online. Make sure the glass is really clean.

 

[clevername]

You 100% dont have to have stronger silicone.

Think about it.. the overflow box is INSIDE the water meaning there is so little pressure put against it. If anything, you can use LITTLE silicone. The overflow box basically floats, you just want a waterproof seal.

spend the $4 and you will be fine.

 

[JTL]

You 100% dont have to have stronger silicone.

Think about it.. the overflow box is INSIDE the water meaning there is so little pressure put against it. If anything, you can use LITTLE silicone. The overflow box basically floats, you just want a waterproof seal.

spend the $4 and you will be fine.

A glass box full of water sure isn't going to float.

 

[JTL]

RTV 108 is twice as strong as the generic silicone available at home improvement stores. You'll probably have to get it online. Make sure the glass is really clean.

RTV is the stuff to use but it will not cure under water. I tried it a while back.

 

[ca1ore]

Even if it would cure under water, it'd kill all your livestock in the process. FWIW, most skim boxes are positively buoyant because the water level is lower. Why not use a skim box with a back and attach it via bulkheads. No siliconing required.