Resealing my 4ft tank

[Wayne487]

I'm having problem getting rid of the old sealant, I have a Stanley knife blade and I'm sure that to cut the silicone out but I'm finding it hard to get the old silicone off.

Any tips would be really appreciated!!

 

[Fishfur]

This is a seriously finicky task. It will take some effort. I bought a box of 100 razor scraper blades and went through at least ten on a 25G tank alone. Once they dull they don't work well. Once I got as much off with blades as I could, I used plastic or mesh scrubbies, and then I filled the tank, and that showed me a bunch of spots I missed.

I learned that a razor scraper with a long handle and bent neck worked better for most of the job, and one with a very short handle was good for the inside corners. Slide the blade under the old sealant and run it along as best you can and pull off as much as you can each time. Once the bulk is off, you get to the nitty gritty picking at the last skinny layer stuck down tight. It's a pain. I got the long handle scraper at an auto part store, as it happens. The short handle one at a hardware store. Both use the same blade, a heavy razor type with a reinforced back piece. Stanley makes them.

Take care not to cut into the seal between the panes.. that is what holds the tank together. Only go to where the panes meet, not between them. It is actually fairly tough to penetrate between panes, but if you push hard you can. So be careful.

I use a vacuum to suck up the annoying bits.. easier that way. It will take a lot of 'elbow grease' to get it done, and any that is left behind will prevent new silicone from sticking too. sigh.. it is not as easy as one hopes it will be, but you will get there.

I advise tape once you get to the new sealant, it helps make nice neat lines. Don't worry if silicone goes on the glass here and there, it will come off pretty easy once dry. Messy to try and get off when wet.

 

[Wayne487]

Thanks, I was unsure as to whether to do a reseal but worry got the best of me and in glad it did since I found water under some of the silicone and I've only done one end of it. I'm using just the blade so I can get in closer to the glass

it's kinda hard to stay away from the bits holding the tank together I think I may have nicked it already Im hoping not too much but it definitely didnt go all the way through so if I put plenty of silicone back there it'll be ok, won't it?

 

[Fishfur]

Should be. You'd have to cut right through it and over some length for it to have much effect, but I have seen someone muscle on through and manage to cut about six inches of pane seal, and I'd be too afraid to risk a cut that big.

I don't know what he did with the tank, it was just a casual observation. But with a cut that big I'd think you are looking at rebuilding the tank, and on a tank that size I would never trust a home job unless the person did it for a living. I know when I tried to replace a pane, end pane, on a 20, I had a heck of a time cutting that seal, and eventually broke the pane.. good thing it was already damaged.

I have a four gallon I am going to rebuild though, as I did cut the seals.. first tank I ever tried to fix, did not realize I'd cut so deep. Noticed when I saw light shining through some holes in the black silicone. More scraping, darn it. Very thin glass, so not hard to cut that seal. Your tank has much thicker glass, so should not be an issue.

 

[Wayne487]

Yeah I think ill be ok then maybe a 10mm cut and not all the way through so I think I'm good.

Starting to get the hang of it now but hurting my fingers now :-( lol managed 1 corner (kind of since its so thick, will I need to make it as thick on the bottom?) and around 15 inches of the bottom

 

[Fishfur]

The trick when you put new sealant in, is not to put it on too thick. Cut the caulk tube nozzle pretty small, and if it is not a skill you know, practice on a box first. You want a fairly thin bead, even as can be. When you get to the corner, you do tend to get more as you turn, but you will smooth it out with a finger when you have it all on. Any excess can be wiped off, and you smush it down so at the edge that touches the glass it is down to nothing in thickness.. the taped edge. Corners I usually have to wipe some out, it is hard to get it really neat unless you do a lot of it and get practiced at it.

You'll need a caulking gun.. very cheap at hardware or paint dept's.

If you tape, remove it before the silicone begins to skin over, which can start in less than a half hour. Once skinned, it will take a lot of the wet stuff with it when you pull the tape and you will likely have to do it all over again, which is a terrible thing to have to do. So yank tape it as soon as you finish smoothing out. If it smears, no worry, you can scrape if off when dry. Not as hard as scraping out the thick stuff at all.

Ideally, you get a neat line about a quarter inch wide on each side of the angles where the panes meet. Up to a half inch is fine, but won't look as tidy.

 

[Wayne487]

I have a caulking gun but its pretty old and kinda stiff to use so I may buy a shiny new one tomorrow hopefully I can get the rest of this silicone off tomorrow when I have new blades since both mine are making it harder to do already you can see they're going blunt. The silicone on the bottom is really thick I'm not sure if the old owners did a reseal since some of it is kind of messy and now what I'd expect from a manufacturer standard

Pictures taken with one of my blades to try and show scale and another using my finger, is that the sort of thickness I need when re-sealing?

 

[Fishfur]

Certainly no thicker.. it does not have to be very thick at all. It can be less than 1/8" thick where the two pane edges meet, then spread thinner and thinner to nothing at the inside edge of the silicone. So long as it covers those meeting pane edges and a bit more, it's fine. If you make it too thick it will take a few days to cure, rather than overnight or so.

It is more insurance than necessity, as it happens. Many high end tanks are made with no sealant inside the tank at all, just the seal between the panes.

 

[Wayne487]

Certainly no thicker.. it does not have to be very thick at all. It can be less than 1/8" thick where the two pane edges meet, then spread thinner and thinner to nothing at the inside edge of the silicone. So long as it covers those meeting pane edges and a bit more, it's fine. If you make it too thick it will take a few days to cure, rather than overnight or so.

It is more insurance than necessity, as it happens. Many high end tanks are made with no sealant inside the tank at all, just the seal between the panes.

Ah right thanks for all your help its been a big help, wish I could afford such a tank that needed no sealant like that but I can dream I assume them to be a lot lot more expensive due to more care having to be taken during production. Hopefully all goes well and I don't have 200L flowing across my living room floor next week. I will hopefully be stripping it tomorrow and resealing Friday/saturday leave it to dry till Monday/Tuesday and filling it up to check for leaks. I will post pictures once its setup fully and not leaking (fingers crossed) will also show the custom built stand I'm 80% finished with.

 

[Fishfur]

Sounds good.

Once you are done, you fill it and let it sit for a few days to test it. In a place where leaks are manageable. Bathtub for me.. biggest tank is 30G.. garage, basement with drain in the floor or laundry room.

 

[Wayne487]

Sounds good.

Once you are done, you fill it and let it sit for a few days to test it. In a place where leaks are manageable. Bathtub for me.. biggest tank is 30G.. garage, basement with drain in the floor or laundry room.

Hmm this may be a problem for me, I live in an apartment above a bar so may have to find somewhere on ground level outside to test it, intact I may have to do it somewhere else since I don't want to do it indoors as any leaks may go through to downstairs which wouldn't be good, If I fill it Monday or Tuesday i will probably leave it 3 days before emptying and moving to where I want it thanks again for the help