Resealing Overflow WHILE tank is running. ?

[Squatch XXL]

My reef chronicle outlines my whole build including more than a few photos. What I noticed today is that there is a 1" long section on my right side overflow that is not sealed. It needs re-sealed, and that brings me to a few questions.

I have reef-safe aquarium sealant, so that is good.

I will have to drain about half the tank's water for 24 hours to allow me to clean and prep the area AND to allow for the glue to cure.

Here is my question. Can I/Should I silicone over the spot I missed OR should I remove all old silicone first? I am really peeved that I did not notice this sooner.

 

[cracker]

So this is just an over flow right? It doesn't have to look pretty? Now I bet there will be disagreement on this but I would apply a big fat bead over the existing silicone,making sure the old is covered well.

 

[DaveK]

Usually silicone will not stick to itself. Usually this means a complete removal and redo, but since this seems to be inside the tank, you might get away with what you plan.

Another thing you find is that the one inch where it's leaking is because the water got in one place but comes out another place. It that case, it's a complete redo of the silicone job.

 

[SubRosa]

All silicone jobs are total removal and replacement jobs. A leaky overflow won't normally cause a problem. Until the power goes out.

 

[Squatch XXL]

A leaky overflow won't normally cause a problem. Until the power goes out.

This is my exact issue. My 20g sump is more than enough for my tank....however the overflow has the potential to leak out 17 extra gallons atop of the normal "power out" level.

As for my "fix", I never applied silicone to the inside of the overflows because I could not fit a caulk tube and gun in at the angle to seal it up......However the little metal squeeze container of aquarium silicone fits just nice.

I drained out the tank past the leak, siphoned out the extra in the overflow, then used paper towels to wick out the rest. I then cleaned the area good with RO water, then hit it with a hair dryer. After that, the new beads of caulk went in against the glass and acrylic no prob.

It doesn't have to look pretty

With this being a totally custom DIY build, I have to disagree. I luckily could apply silicone against the inside of the joint, so it kept it out of the DT....The other "issue" is that silicone does not like to stick to cured/dry silicone the way that one would think. It would probably work to slather it all over the top of my current layer, but TBH it would look terrible.

IF this fix does not work, I will have to strip the caulk on the outside.....which happens to have a light layer of paint atop of it....which means that IF I have to re-caulk, it will HAVE to be black caulk to match the background and overflows.

This is what I consider a "low pressure" issue. The pressure difference between the tank and the overflows is minimal, but IF there is a leak water will find it.

Thanks for all the great advice, and hope this works.

 

[Squatch XXL]

Well, it was not a total success. There is a very slight leak. I may have had less than an oz of water sneak into the box over a half hour. This is a huge failure waiting to happen, and my recourse will be to install a shut off valve for the event that power goes out while I am home, and a larger sump for other events.

This was my first DIY build, so I expected some issues. My overflow boxes were certainly tricky because of their small footprint.

Note to self: While Im looking at my 38g tank, Go crazy with the caulk in the future

Ill be doing a test to see how much of a leak is still present. If I leak past a gallon in an hour If I was leaking more than a quart an hour, I would be concerned. This is minor.

 

[PSU4ME]

Well at least you were able to test it! I don't like patching silicone because I never get it to hold