At what point do you stop trusting your tank?
 

Here's the deal. I have a 130 gal tank that was purchased used about 12 years ago. It's 6 feet long, made by Hagen, but with no bracing at all. There is a noticeable bow in it when full. We had it set up with freshwater for several years with no problems, and for the past 3 years it has been used only as a Paludarium, but is currently just sitting dry. I'd love to get this going again as a FOWLR at least to start, but I'm just not sure how much I trust it anymore. Do I have any reason to be worried?

Wellllll ... kinda maybe sorta?

I guess the thing is, silicone is only good for so long. The good news is that silicone can be redone.

The glass should be OK though. Might be a bit scratched up though .. I find that older tanks tend to look their age.

I'm sort of in the same boat, my 75g has been running now for 4 or 5 years under my care, and it was used (quite used) when I got it, it's probably nearly 15 years old. I gotta get on with upgrading and taking it down and turning it into a water change tank or something instead.

i wouldnt setup the tank again after it's been sitting dry for so long without redoing the silcone. the tank is about the cheapest part of redoing a setup, look into just getting a new tank maybe.

Thing about commercially built tanks is that all the strength comes from the siliconce contact on the edges ... the bead of silicone on the inside is mostly to make sure it is waterproof because you can get bubbles on the edge glueing that would allow water to leak out.

As Tony has stated the silicone does deteriorate over time.

If you want to be sure because of the investment you are about to make ... get some GE1200 silicone ( look in the phone book in your area for GE silicone dealer ) ... the silicone has to be 100% silicone ( watch out for the home hardware store brands as they can contain mold resistant chemicals which would kill everything in your tank )

Use a razor and cut off all the silicone from the corners ... then get the razor into the edges between the glass ( I have found that you might have to use very thin wire with 2 wooden or pvc handles ... like a garrote ... to slide between the glass to seperate them ... once you have all 5 pieces seperated ... clean each edge with a razor to be sure there is no silicone residue ... when you are ready to put it back together clean the edges with vinegar and water ( to make sure none of the oils from your hands are on the glass ) ... then silicone each edge using duct tape to hold it together ... once the edges cure for at least 24 hrs then reseal the inside corners ... voila ... " new tank " :wink:

You may want to also add eurobracing or a cross support to add to your peace of mind and stop the bowing

I am always wery of a tank that is bowing when full, I have a 100G 5' tank and it has a DIY brace across the top of the tank in the center, a bit of an eye sore as it is made of metal and the trim on the tank is black, but hey it doesn't bow. Maybe check out Golds in Calgary to see how much a new one is (that is if you dont want to do all the work of resealing the old one)
GL

Thanks for the advice guys. Not sure about taking it apart and re-siliconing it myself. I think I would trust it even less at that point. :redface: I wonder how much that would cost to get done by a place that builds tanks...

I would probably sell it as a terrarium & buy a newer (but still used) tank. Most cost-effective & least PITA solution, imo.

Anthony

Usually as much as a new tank, it is a real PITA to take one apart and rebuild. You need to make sure the edges are perfectly clean (use acetone) to be sure of a good bond.

I also don't think I'd trust it anyway, if you are seeing a lot of bowing it could mean that the front panel is weakening. 130 gal is one hell of a mess.

I never (fully) trust a large tank after I've moved it once, but I have to say that the (old, at least) Hagen tanks were sure built to last. My dad's 72 gallon Hagen just sprung a leak last year - after 25 years of continuous use.

If you're going to reseal it, I'd encourage you to get it done by someone who builds tanks professionally, as the slightest imperfection in the surface where you're assembling it, or the glass being slightly out in the seal will translate to a whole lot of misplaced pressure.. Probably not a big deal, but over the years is a little risky.

And just to say it (for future readers of this thread), cutting out the silicone from the inside of the tank and not actually separating the panes of glass isn't worth doing - the overwhelming majority of the strength of the seal comes from the silicone that's sandwiched between the panes. The stuff you actually see isn't doing a whole lot.

Go
 

Too bad you don't live near me Kryten - I'd buy it off of you "cheap" :mrgreen:

I've resiliconed many tanks over the years with good successs, though I've never had the need, or desire, to take the internal silicone out as Buk_A_neer and Rikko suggest. Once you mess with those seams it is a crap shoot and there's no reason to assume that they have weakened. Tank leaks occur when there is a failure with the water contacted beads. This occurs because they are continously exposed to water and over time they weather and weaken. The bond between the panes is not exposed to air or water and lasts a very long time (unless stressed by moving or flexing as Rikko suggests). I don't think telling people to completely strip their tanks when they need resiliconing is really practical (IMHO)

Oddly enough, I am actually redoing a drilled 130G. right now that I've picked up for $50.

It is true that having someone else do it for you will probably cost as much as a new tank though. The labour is fiddly if you want to ensure a good seal by removing all the silicone but it really isn't that difficult. I guess I like to tinker (or may be I'm a little too scottish :wink: )

Here's a link where I describe the process
http://www.aquahobby.com/board/viewtopic.php?t=35335

Oh well, If you're ever passing through with that 130, you can always give me a call :biggrin:
________
vapourizers