Second Hand Tank - seals good or not?

[ctripp]

Hi everyone,

I have purchased a second hand tank with some extra bits for a pretty decent price. Had my eye on this tank to buy new, so pretty chuffed to get a good deal on a second hand one. It’s a DD 1200, which will be an upgrade from my Fluval Evo!

Just looking for some advice/reassurance on the seals.
The joints hold the glass together look pretty solid (happy to stand corrected if someone thinks otherwise), it’s just the corners inside the tank are a bit worn.

Short of tearing the glass apart and re-sealing the whole thing. Can I tidy up the edges and leave it? Tidy up the edges and run a bead of silicone over it to add a bit of protection?
Or is it okay and just leave it? I’ve added some pictures of it dry and wet.

Currently doing a water test on it and it’s holding up okay with no leaks.

Any advice is appreciated!
(This is my first ‘big’ tank, so will probably asking a lot of silly questions going forward. Bit of a tightarse as well, so might be looking to some of those AliExpress dupes for various bits of equipment)

 

[Drewe]

I'd personally look elsewhere. Depends on your risk tolerance. A lot of that just looks like someone being careless with an algae scraper. In my non-professional opinion, if it did leak I'd imagine it would be a slow leak and not a panel blowout. Again, I personally wouldn't. Plenty of used tanks out there without these issues.

 

[edsbeaker]

That bottom seal to me looks very questionable. I’m not sure I would be comfortable using that tank as is. It reminds me of what some of the Red Sea seam fails look like before they fail.
I’m no expert, so wait for more opinions, but that looks risky especially taking into consideration the condition of the silicone throughout the tank.

 

[UncommonSense]

Could you try to get photos of the bottom seal and corner seals in better lighting? It’s hard to say if there’s just a reflection off the glass in several photos, or if there’s actually issues with the seals!

 

[edsbeaker]

These three photos of the bottom are concerning in my mind. I’m not sure if the seams are starting to separate and that is sand or other particles in there?

 

[UncommonSense]

These three photos of the bottom are concerning in my mind. I’m not sure if the seams are starting to separate and that is sand or other particles in there?

Agreed!

I’m also looking at these thin lines in the middle of the corner seal…

 

[ctripp]

Cheers for the feedback guys!
Here’s the inside of the of the corners and close up on the front seal. The bottom front seal looks as if it is just scraper damage? Only goes in couple of mm compared to the whole seal

Agreed!

I’m also looking at these thin lines in the middle of the corner seal…

I think this line is just the reflection of the edge of the seal on the inside, through the pane of glass - it’s normal to see this, or no?

 

[Clowning_Around72]

Remember, you will have multiple powerheads moving water around. You will also have a lot of $$ tied up in livestock. For a QT or a holding tank, no problem, but if you have doubts, I'd avoid it

 

[UncommonSense]

it’s normal to see this, or no?

It really depends on the lighting and reflection; if you shine a flashlight through the glass on each side of each silicone joint; you can see if the silicone is separating from the glass in any way fairly easily!

Here’s what I mean; see the lighter and darker areas inside the joint when the photo is zoomed in? — can we get a good light on those and higher resolution photo(s) looking at the silicone seal through the glass?

 

[get-salty]

That bottom seal is on its way out. I'd 100% reseal the entire tank asap.

also, Do not apply silicone over silicone , it will not hold ! You must remove ALL off then apply new one.

Good luck

 

[ctripp]

It really depends on the lighting and reflection; if you shine a flashlight through the glass on each side of each silicone joint; you can see if the silicone is separating from the glass in any way fairly easily!

Here’s what I mean; see the lighter and darker areas inside the joint when the photo is zoomed in? — can we get a good light on those and higher resolution photo(s) looking at the silicone seal through the glass?

I think I’m understanding.
Are these pictures any better? (Side seals)

 

[rayadog]

One of those bottom corners almost looks resealed. Additionally, one of those standing corners looks too worse for wear to not give me anxiety. If you need the tank, I’d try to reseal or double up (at the very least); after I learned how to do that lol.

 

[UncommonSense]

I think I’m understanding.
Are these pictures any better? (Side seals)

Yes, these pics are much better!

Possibly add some detailed pics of the front bottom seam as well? That is the most critical one!

The vertical front seals do not appear to be delaminating from the glass, but there is some minor to moderate damage from over-enthusiastic scraping into the actual structural component of the seal…

I agree that this tank deserves an interior reseal; ideally with seam reinforcements!

I personally don’t believe in using anything but glass for a silicone seam guard/reinforcement, given that the bond between silicone and glass is technically chemical, more than mechanical…

Reference my tank thread if you’re curious to see how I reinforced my 180g! — something similar could work in your situation; in fact, I’m actually planning on fabricating another batch of right pentagonal profile glass rods soon if you’d be interested in going that route?

— alternatively, square/rectangular profile extruded glass rod can be sourced (they are not plane along their faces due to being extruded, unfortunately)… or, you can have a glass shop make you custom narrow rectangle bars!

some high end aquarium manufacturers that shall remain unnamed actually use equilateral (60*) triangle profile extruded glass capillary rods (definitely not what I would recommend!)…


That failing R450 I referenced earlier is getting a full interior glass seam reinforcement/bottom euro/center braces just as an experiment to see how well moving the entire structural tank seal inboard works in the real world! (The tank is also not going to live in the house, and is on a concrete pad with drainage!)

 

[ctripp]

Yes, these pics are much better!

Possibly add some detailed pics of the front bottom seam as well? That is the most critical one!

The vertical front seals do not appear to be delaminating from the glass, but there is some minor to moderate damage from over-enthusiastic scraping into the actual structural component of the seal…

I agree that this tank deserves an interior reseal; ideally with seam reinforcements!

I personally don’t believe in using anything but glass for a silicone seam guard/reinforcement, given that the bond between silicone and glass is technically chemical, more than mechanical…

Reference my tank thread if you’re curious to see how I reinforced my 180g! — something similar could work in your situation; in fact, I’m actually planning on fabricating another batch of right pentagonal profile glass rods soon if you’d be interested in going that route?

— alternatively, square/rectangular profile extruded glass rod can be sourced (they are not plane along their faces due to being extruded, unfortunately)… or, you can have a glass shop make you custom narrow rectangle bars!

some high end aquarium manufacturers that shall remain unnamed actually use equilateral (60*) triangle profile extruded glass capillary rods (definitely not what I would recommend!)…


That failing R450 I referenced earlier is getting a full interior glass seam reinforcement/bottom euro/center braces just as an experiment to see how well moving the entire structural tank seal inboard works in the real world! (The tank is also not going to live in the house, and is on a concrete pad with drainage!)

I checked it out, looks good.
Not sure the glass would make the journey across the sea though!

I have attached pictures of the bottom seal.

When we talk around re-sealing (with or without the filler), is it clearing the old fraying damaged silicone, but leaving the joint connecting the glass, then re-applying silicone to the surrounding glass?
I’ve tried to mock up some images to try and understand it…

 

[UncommonSense]

Not sure the glass would make the journey across the sea though!

I can get pretty creative with packaging! — think PVC pipe with foam fit to each bar; but you can likely replicate my work or get a glasscutter to do it for cheaper!

When we talk around re-sealing (with or without the filler), is it clearing the old fraying damaged silicone, but leaving the joint connecting the glass, then re-applying silicone to the surrounding glass

Yes, this is what we’re talking about! You typically don’t want to touch the joint connecting the glass panes unless the whole tank is getting rebuilt completely… we're just looking at redoing the silicone on the inside of the tank, outside of the glass:glass seam!

The images you mocked up are great! They explain the silicone seal well! — I’ll just add that the glass reinforcement would typically be a square rod profile or similar right angle rod profile like a rectangular profile, and placed all the way into the tank’s interior corners (vertical and horizontal seams)!

(Though I like your idea to add a strip with 45 bevels on long edges into the interior corners! This isn’t how glass is typically cut [score/snap right angle edges] but I could probably make something like this on my abrasive wet cut saw, or you could pursuit it further!)

 

[ctripp]

I can get pretty creative with packaging! — think PVC pipe with foam fit to each bar; but you can likely replicate my work or get a glasscutter to do it for cheaper!


Yes, this is what we’re talking about! You typically don’t want to touch the joint connecting the glass panes unless the whole tank is getting rebuilt completely… we're just looking at redoing the silicone on the inside of the tank, outside of the glass:glass seam!

The images you mocked up are great! They explain the silicone seal well! — I’ll just add that the glass reinforcement would typically be a square rod profile or similar right angle rod profile like a rectangular profile, and placed all the way into the tank’s interior corners (vertical and horizontal seams)!

(Though I like your idea to add a strip with 45 bevels on long edges into the interior corners! This isn’t how glass is typically cut [score/snap right angle edges] but I could probably make something like this on my abrasive wet cut saw, or you could pursuit it further!)

Ah okay, yes!
So as long as I have a good majority connection and not only on old silicone I will be fine?

Any tips on getting a good finish and strong bond?
Other than the usual, make sure the old stuff is gone, cleaning the surface and making sure it is dry, taping the edges…

 

[UncommonSense]

Ah okay, yes!
So as long as I have a good majority connection and not only on old silicone I will be fine?

Any tips on getting a good finish and strong bond?
Other than the usual, make sure the old stuff is gone, cleaning the surface and making sure it is dry, taping the edges…

Yes; you want the maximum clean glass bonding area for your new interior seal!

Try to do the work all in one 10min work time application; possibly rent, buy, or borrow an electric caulking gun to apply silicone faster and more uniformly than you can with a manual caulking gun…

Apply new silicone following a L shape; one bottom seam, one side seam in each fluid bead, rotate 90 degrees, repeat! — 4x

I like to use a utility razor to cut the old silicone seam first from the glass pane which glass:glass silicone seals on its edge… this prevents the razor from being able to gouge into the actual glass:glass seal on the first pass! — cut the same interior silicone again on the second cut almost like you’re scraping algae with the razor; at an angle to the glass so the tip of the blade cannot enter the glass:glass seam… take your time here… (I like to use a squared off razor blade for this part)

Pull your masking tape off immediately after wiping your beads to a nice fillet! (only really noticeable clean lines are on the vertical corner seams) — within the ~10min tooling time, or the tape will start to become one with the silicone!

definitely don’t use acetone to clean the glass before siliconing; I had a glass:glass silicone bond fail recently that was prepped with acetone… I’ve since switched to 99% lab isopropyl alcohol or medical alcohol wipes for every silicone to glass application!

The weather affects the curing; higher humidity speeds things up; shoot for <60% humidity when you are applying silicone to get the longest tooling (working) time possible!

Once the silicone has formed a skin (~10mins after exposure to oxygen; work your oldest bead first!), don’t mess with it anymore! You’ll just make an ugly mess!!

Don’t worry about silicone drips or fingerprints on the glass; they scrape right off with a razor once cured!

Oh, and get some good aquarium sealant silicone for this! (Plus, wait the full week after application for maximum cured strength before adding water!)

Best of luck! Some how-tos on this subject are a bit iffy… best bet is to just cross-reference several and make logical deductions, in my experience!

 

[ctripp]

Yes; you want the maximum clean glass bonding area for your new interior seal!

Try to do the work all in one 10min work time application; possibly rent, buy, or borrow an electric caulking gun to apply silicone faster and more uniformly than you can with a manual caulking gun…

Apply new silicone following a L shape; one bottom seam, one side seam in each fluid bead, rotate 90 degrees, repeat! — 4x

I like to use a utility razor to cut the old silicone seam first from the glass pane which glass:glass silicone seals on its edge… this prevents the razor from being able to gouge into the actual glass:glass seal on the first pass! — cut the same interior silicone again on the second cut almost like you’re scraping algae with the razor; at an angle to the glass so the tip of the blade cannot enter the glass:glass seam… take your time here… (I like to use a squared off razor blade for this part)

Pull your masking tape off immediately after wiping your beads to a nice fillet! (only really noticeable clean lines are on the vertical corner seams) — within the ~10min tooling time, or the tape will start to become one with the silicone!

definitely don’t use acetone to clean the glass before siliconing; I had a glass:glass silicone bond fail recently that was prepped with acetone… I’ve since switched to 99% lab isopropyl alcohol or medical alcohol wipes for every silicone to glass application!

The weather affects the curing; higher humidity speeds things up; shoot for <60% humidity when you are applying silicone to get the longest tooling (working) time possible!

Once the silicone has formed a skin (~10mins after exposure to oxygen; work your oldest bead first!), don’t mess with it anymore! You’ll just make an ugly mess!!

Don’t worry about silicone drips or fingerprints on the glass; they scrape right off with a razor once cured!

Oh, and get some good aquarium sealant silicone for this! (Plus, wait the full week after application for maximum cured strength before adding water!)

Best of luck! Some how-tos on this subject are a bit iffy… best bet is to just cross-reference several and make logical deductions, in my experience!

This is really helpful! Thank you so much!

 

[UncommonSense]

This is really helpful! Thank you so much!

Of course!

One more thing:

Consider buying a second tube of silicone sealant primarily so you can use it to practice on some arbitrary object like wood scrap! This will help you test the electric caulking gun for feeds and speeds…

In addition; it will help you wrap your head around how and when to peel your masking tape, how to cleanly wipe the silicone without smearing if everywhere (I like to have a alcohol soaked rag handy for finger cleaning!), and how strong this stuff is when you get a good bond!

The second tube of silicone also means you have excess for the reseal if you go too liberal on your beads with the first tube! (I like to stick a screw in the end of a caulking tube that is partially used to preserve the remainder for later!)

Good luck! It’s a great skill to have!