Resealing a used tank?

[Neoalchemist]

I have no skin in the game here really, but was doing some research on resealing tanks not too long ago.

I linked Momentive RTV 108 because it is highly recommended by professionals and you will find it mentioned all over Reef2reef and reefcentral as THE silicone for building and re-sealing tanks.

having a humid environment is different than being submerged.

It took 3 trys for me to get my 120gallon resealed well enough for me to be happy with it. 1st time looked like ****, 2nd time I didnt get the tape off in time and it skinned at the end, 3rd time I got a helper and taught them how to run the gun on some scrap glass so I could follow along and smooth it. For larger tanks a helper is critical, you just cannot move fast enough.

Thereason you had to move so fast is likely because of a too dry environment. The drier the environment the faster the silicone forms a skin. If it forms a skin too fast it doesnt have time to bond to the surface.

 

[Fishingandreefing]

Let me first start by saying i know this is not the proper method of resealing a tank, proper method would be removing all the panes of glass and redoing every joint and corner, but what i have done in the past is cut the corner beads out, clean the corners with alcohol, i taped the glass where i want the new joints to be, i wanted nice clean edges then used ASI adhesive to replace the older silicon/adhesive. I used the ASI from BRS, it worked on my current sump and a 34gal solana i resealed several years ago. Mind you these were not big 100+ gallon tanks with tons of water volume.

That actually sounds relieving and it make sense. We all know that new silicone will not bond cured silicon but if I cut and clean out the old silicone, use acetone to clean it then reapply new silicone. The new silicone actually bond onto the glass surface. It’s a 70g rimless tank that I picked up from a member here.

 

[Fishingandreefing]

Thanks for those that commented and here are the pictures. Again, it’s a 70g and the glass is 10mm

 

[Fishingandreefing]

Pictures

 

[Fishingandreefing]

I am thinking Momentive RTV 103 is the top choice

 

[KrisReef]

The bond that holds the tank together is between the edges of the glass panes. When you just cut away the old silicone in the corners ( and don’t take the tank completely apart) then you are not going to get the original seal strength that you might need.

 

[Fishingandreefing]

The bond that holds the tank together is between the edges of the glass panes. When you just cut away the old silicone in the corners ( and don’t take the tank completely apart) then you are not going to get the original seal strength that you might need.

True, but I think it wouldn’t hurt to reseal it. Based what I am reading, between the glass it holds the structure and the beat outside is to prevent leaks, and that’s what my intention is Hopefully it helps and perhaps if I do an ok job, it helps to reduce eye sores too lol

 

[mrlavalamp]

True, but I think it wouldn’t hurt to reseal it. Based what I am reading, between the glass it holds the structure and the beat outside is to prevent leaks, and that’s what my intention is Hopefully it helps and perhaps if I do an ok job, it helps to reduce eye sores too lol

This is pretty much correct.

The strength and main seal on the aquarium is found between the panes of glass. Some information I found suggested that some tank makers actually use a silicone ADHESIVE instead of a SEALANT on this joint, and then use a standard sealant inside corners. My research seemed to suggest that this adhesive was actually momentive RTV, but not 100% on that.

The inside seal is there to add a VERY small amount of reinforcement, but mainly to protect the main seal from damage/minute imperfections that would allow water to ingress and start a leak.

Momentive 103 is the black version, 108 is the clear version. Exactly the same properties otherwise.

Removing the interior seal and re-applying is totally fine. Once the main seal between the glass is compromised and the tank is leaking, the ONLY way to actually fix it is to break the tank down completely, anything else is just a bandaid.

Breaking the tank down completely is a MUCH more daunting task, and on a larger tank (anything 55g+ for me) I wouldnt even think about it, just get rid of it on craiglist to someone with reptiles/rodents, or cut up the glass and repurpose it as a small tank.

 

[Fishingandreefing]

This is pretty much correct.

The strength and main seal on the aquarium is found between the panes of glass. Some information I found suggested that some tank makers actually use a silicone ADHESIVE instead of a SEALANT on this joint, and then use a standard sealant inside corners. My research seemed to suggest that this adhesive was actually momentive RTV, but not 100% on that.

The inside seal is there to add a VERY small amount of reinforcement, but mainly to protect the main seal from damage/minute imperfections that would allow water to ingress and start a leak.

Momentive 103 is the black version, 108 is the clear version. Exactly the same properties otherwise.

Removing the interior seal and re-applying is totally fine. Once the main seal between the glass is compromised and the tank is leaking, the ONLY way to actually fix it is to break the tank down completely, anything else is just a bandaid.

Breaking the tank down completely is a MUCH more daunting task, and on a larger tank (anything 55g+ for me) I wouldnt even think about it, just get rid of it on craiglist to someone with reptiles/rodents, or cut up the glass and repurpose it as a small tank.

I went ahead and ordered the momentive rtv 103. Price seems jacked up either due to popularity or discontinued? Just like hand sanitizer or mask that sells like 5 times if not more due to the virus.

Anywau, I could have just sell it but I want to give it a shot because a member here gave his entire system to me so.

On a side note, a friend of my did what I want to do for a few tanks and had no problem with it.

again, thx for all that commented.

 

[Fishingandreefing]

So, I cleaned the inside of the tank and found only the front as shown in pictures are looking bad. I was thinking just resealing the front only, just the left and right not even the bottom.

now would that be an issue since I will be stopping at the corner by a cut?

 

[mrlavalamp]

It will eventually be an issue.

Silicone will not stick to cured silicone at the place you cut it.

depending on exactly HOW you do it, it might be ok and last a while, but there will always be a weak spot there and I would worry about it forever (or at least until I have lost enough sleep to have other bigger problems).

I cannot say how long it will last, but new silicone over old silicone was one of the reasons I redid my 120. it was a used tank and previous owner had messed up the interior seal with a scraper, then tried to fix just the corner he messed up. I could tell what he had done right away because the two layers of silicone were peeling apart. It was not leaking though, and the new silicone was stuck to the glass pretty well, just not where it overlapped the 45 degree bevel he had made in the old silicone to try and create a transition of some sort.

 

[mrlavalamp]

should mention he said he patched that corner a year before I got the tank, and he was using it as a freshwater tank, not sure if salt water would have made a difference.

 

[Fishingandreefing]

It will eventually be an issue.

Silicone will not stick to cured silicone at the place you cut it.

depending on exactly HOW you do it, it might be ok and last a while, but there will always be a weak spot there and I would worry about it forever (or at least until I have lost enough sleep to have other bigger problems).

I cannot say how long it will last, but new silicone over old silicone was one of the reasons I redid my 120. it was a used tank and previous owner had messed up the interior seal with a scraper, then tried to fix just the corner he messed up. I could tell what he had done right away because the two layers of silicone were peeling apart. It was not leaking though, and the new silicone was stuck to the glass pretty well, just not where it overlapped the 45 degree bevel he had made in the old silicone to try and create a transition of some sort.

Both of the problem areas are approx in the mid front area. My plan is to scrap off the old but not messing with anything on the bottom and bottom corners.

if it’s clean enough, the momentive RTV 103 should bond to the glass. I also I agree that there would be a weak point where the new silicone bonding to the old near the bottom.

really don’t want to take the entire inside beads off, so it seems like either I leave it or spend the few extra hours and hope for better cosmetic look and perhaps strengthen it.

still want to hear more advice and see.