I've just discovered my large tank has a small leak in the bottom in the middle. I thought I might try to seal it with silicone hoping it will work if sealing the outside of the tank only - so my question is, can silcone be applied to a wet surface or is there something else to use?

Sealing the outside will not work, you need to seal the inside. And that's not really garaunteed, best to reseal the whole thing since likely the whole thing is deteriorating.

What is involved in the resealing process? Is that completely removing all silicone so the tank is in bits or resealing over the top of existing silicone?

What is involved in the resealing process? Is that completely removing all silicone so the tank is in bits or resealing over the top of existing silicone?

The former. You'll need to completely tear down the whole tank. If one part has degraded enough for it to start leaking most likely the rest of the silicone isn't in much better shape.

Ideally what Ira has said.

However i have just repaired the mine which has been duct taped on the out side for a couple of months.

I fixed the immediate leak only.I transferred all to a bucket clean it then refilled to find out exactly where the leak was. (its not always where it leaks out) and with mine i found that water got behind the silicone then travelled down to where it could drip out a pin hole.

As it was near the bottom of the tank i cut out the silicone form a bit above the leak and down to the bottom. You need to use a very sharp blade to cut clean and not compromise the rest of the join. Completely cleaned the join removing all existing silicone and resealed then let cure before refilling. Key is to make sure you don't interfere with any silicone that you are not removing and make sure you remove all the old stuff and clean thoroughly.

If i had the time id redo the whole tank as like Ira says the rest will probably start to give soon. Silicone does not last for ever.

Ideally what Ira has said.

However i have just repaired the mine which has been duct taped on the out side for a couple of months.

Brilliant! Why didn't I think of that! :rotf: I've just spent all afternoon mucking about with a sealant and getting it all over me more than the tank so then had to go out and buy turps and, well - you get the idea. I should have just duct taped it up!

I fixed the immediate leak only.I transferred all to a bucket clean it then refilled to find out exactly where the leak was. (its not always where it leaks out) and with mine i found that water got behind the silicone then travelled down to where it could drip out a pin hole.

As it was near the bottom of the tank i cut out the silicone form a bit above the leak and down to the bottom. You need to use a very sharp blade to cut clean and not compromise the rest of the join. Completely cleaned the join removing all existing silicone and resealed then let cure before refilling. Key is to make sure you don't interfere with any silicone that you are not removing and make sure you remove all the old stuff and clean thoroughly.

If i had the time id redo the whole tank as like Ira says the rest will probably start to give soon. Silicone does not last for ever.

I can see the leak as the particular spot where it's leaking is coloured green and only in that spot so it's definitely in the middle of the front of the bottom of the tank, which means a complete empty to fix the problem.

So, I think if I have to empty it to do that, I may as well redo the whole thing as Ira said. So, now need to find someone to help me with that, as you can see - me and sealant don't mix :roll:

I just had the damn lid made too and seriously doubt I'll be able to get that guy back again to help me :facepalm:

Does anyone know of anyone who can reseal tanks, I'd be willing to pay of course.

It's pretty easy to do it yourself if your handy ? You will need some special silicone that can be used in tanks (about $15) a silicone gun (about $5-$35) a set of super thin blades (not the craft knife style you can get thinner better ones that are similar to the old school shaving razors about $10). From there its CAREFULLY using the blade to cut away the silicone (although I don't recommend it for first timers you can use turps to remove excess but it needs a few washes and dry outs before it safe for fish use). From there you can lightly apply a bead of silicone all around the tank(less is more seriously you can always add more but removing is messy) and use either a Popsicle stick or your finger to press it down. If you aren't confident with silicone (and who is haha) you can invest in a roll of painters masking tape to use down the edges to get the perfect line. also forgot to say you need a rag or paper towels for clean up

Its a fiddly job an usually takes a few hours to do it... but its easy if you take your time, put on some music and do it in the sun/shade :thup:

Another trick that we use is once you have applied silicone to join making sure that it is a nice constant bead with no gaps, lightly spray the silicone and the surround glass with a spray bottle filled with water and a couple of drops of detergent.

this prevents the silicone sticking to everywhere where you dont want it to.

You can then use a popsical stick or you can get some little silicone tools from bunning for about $3 pack of 4. They are way easier to use and clean the silicone up to however you want it with varying sized champers.

If the siluicone is failing I would pull the tank apart, clean off existing and reglue and seal it. Nothing worse than a nicely set up tank that comes apart and makes a mess and kills your fish.

If the siluicone is failing I would pull the tank apart, clean off existing and reglue and seal it. Nothing worse than a nicely set up tank that comes apart and makes a mess and kills your fish.

Splitting can be quite difficult though but yea definitely agree if you can do this. I remember I brought this 90cm tank of TM I cleaned and cut for AGES but not matter how much I tried I couldn't split it.... :gigl:

It's pretty easy to do it yourself if your handy ? You will need some special silicone that can be used in tanks (about $15) a silicone gun (about $5-$35) a set of super thin blades (not the craft knife style you can get thinner better ones that are similar to the old school shaving razors about $10). From there its CAREFULLY using the blade to cut away the silicone (although I don't recommend it for first timers you can use turps to remove excess but it needs a few washes and dry outs before it safe for fish use). From there you can lightly apply a bead of silicone all around the tank(less is more seriously you can always add more but removing is messy) and use either a Popsicle stick or your finger to press it down. If you aren't confident with silicone (and who is haha) you can invest in a roll of painters masking tape to use down the edges to get the perfect line. also forgot to say you need a rag or paper towels for clean up

Its a fiddly job an usually takes a few hours to do it... but its easy if you take your time, put on some music and do it in the sun/shade :thup:

Oh gawd, there's no way I can do this - the tank is very tall so I'd need someone to help me hold it in to place, let alone the rest

The leak has actually got worse so it will have to be done fairly urgently now - I'll need someone to come and do it as the tank is too big to fit into my car - please can someone help!

if tank is very tall the bottom middle is where the most pressure is

drop water level to reduce pressure on that spot

gladwrap on the inside where the leak is to slow it down?

if tank is very tall the bottom middle is where the most pressure is

drop water level to reduce pressure on that spot

I noticed this only actually started after I topped the tank up (I had the level low as there was no lid, but once made could top it up and that's when the leak started) - unfortunately lowering the level hasn't helped - the leaking has got worse and is dripping once every 2 seconds (a metronome in the background :roll: )

Really? Gladwrap? Well I'll try anything at this stage :nilly:

I noticed this only actually started after I topped the tank up (I had the level low as there was no lid, but once made could top it up and that's when the leak started) - unfortunately lowering the level hasn't helped - the leaking has got worse and is dripping once every 2 seconds (a metronome in the background :roll: )

Really? Gladwrap? Well I'll try anything at this stage :nilly:

I think if you have some silicone it would be better than glad wrap. It's fluid enough to if you use a big glob it will get sucked into and through the leak a little and clog it until it sets. But maybe even better is a big glob and then surround it with glad wrap?

The edge of the tank is on the edge of the cabinet it sits on so can't really wrap gladwrap around anyway - I tried some silicone glue stuff and and duct tape and it didn't work - as the dripping has become faster

At this stage, I'd be happy if I could borrow a tank or someone could take care of my fish so I can drain the tank and stop the damage it's doing to the dresser it's sitting on until I can get it remade - of course I'd happy to pay for costs

You could as an alternative get some fish bins from Bunnings or Warehouse etc. Food grade plastic. Use them as holding tanks while you repair the tank. They're pretty inexpensive.

gladwrap or silicone on the inside

I would remove the fish before using silicone under water... Just a thought HFF had some underwater non-toxic glue advitised the other week.

True, but I'm always paranoid that the fish will jump out and that's a very interim measure. I'm starting to think I may have to eat humble pie and ask the guy who made my lids to rebuild the tank - I can imagine how much he'll charge for it though

Surely there are many people in Wellington area who will rebuild the tank for you, have you rung around the local glaziers and seen if any of them have any experience with fixing leaking tanks? I would try some of the smaller business' as they will probably charge alot less and might have some advice at the least.

Have you asked Pete ?

Port Nicholson Glass

Custom built tanks and stands

Nationwide delivery

7 Regent St Petone

Wellington

Phone: 04 939 9030

@ godly, I'll make some calls to glaziers tomorrow - it's a shame it's had to come to that.

@ Graham, the tank is too big to transport so unless Pete makes house calls...

He came to my house in Karori to do a quote for a tank build. Why not just ask him? As a glazier, pretty much all of them do house calls.

Port Nicholson Glass is a name that comes up often, haven't heard a bad thing yet.

The edge of the tank is on the edge of the cabinet it sits on so can't really wrap gladwrap around anyway - I tried some silicone glue stuff and and duct tape and it didn't work - as the dripping has become faster

At this stage, I'd be happy if I could borrow a tank or someone could take care of my fish so I can drain the tank and stop the damage it's doing to the dresser it's sitting on until I can get it remade - of course I'd happy to pay for costs

I was meaning gladwrap and silicone INSIDE. Putting it on the outside won't do any good, the water will just push it off the leak.

Sounds like it's getting past time to give up on patching. Throw everything in the bathtub. Make sure it's plugged well...Bonus is it'll be really easy to do water changes.