Help diagnose source of leak on tank

[JDtimk]

I am dealing with a moderately slow leaking DT and am trying to think clearly about where the leak may be and what my options may be to fix or prepare to tear down etc.

The facts:
Equipment:

• DT single corner overflow 120gal probably marineland or maybe deep blue
• Tank is at least 5 years old and second hand
• Tank has been operating leak free for the past 3 years in the current location
  
• Very solid DIY stand with marine deck paint, but the stand is solid top surface so I cant see the bottom of the tank, except for the cut out for the corner overflow

Timeline:

• 3-6-19 6am woke up to approximately 2 gallons or so of water having leaked onto the floor.
  • wiped up the water and couldn't detect an obvious source of the leak
  • had to go to work and no leak when I returned from work that night
• no further leaks on 3-7-19
• 3-8-19 5pm came home to approximately 2 or so gallons of water having leaked onto the floor. Currently still dripping.

Observations of the leak:

• The water is dripping out from between the bottom of the tank frame and surface of the stand.
• The drip rate is about one drip per second.
  
• There is no evidence of water overflowing the top rim of the tank
  • no drip marks or wetness on the top rim or sides of the tank
  • no pooling up of water on the top edge of the bottom rim
• When I look up into the cut out for the corner overflow I see beads of water condensed on the upper lip of the bottom of the plastic trim where it meets the bottom pane of glass, but it's not visibly dripping from that spot

Miscellaneous info

• No recent bumps or jolts or anything physically different that would stress the tank
• No additions of rock or repositioning of any rock recently

Questions
How could it leak and then stop leaking and then start leaking again?

• My only hypothesis is that maybe salt creep clogged the original slow leak and then was washed out to allow the leak to begin again? but that is my only guess.

Do tanks leak from the bottom silicone or pane that often? I haven't heard of that area leaking but that doesn't mean much I guess.
Has anyone had this type of leak before and know what I might look for or check to confirm a source of the leak?
Worst case scenario, what tank manufacturer or source of tanks do people recommend as a replacement? Would probably upgrade slightly from a 120, but wouldn't want to go much bigger.

 

[Mastiffsrule]

I just had a leak as well,. Mine was thru a bulkhead. Was not clear on your set up but is there a bulkhead in the area?

 

[JDtimk]

There is a bulkhead and I don't see any evidence of leaking from the bulkhead. but even if it was leaking from the bulkhead it would just leak straight down into the sump and not go in between the tank and stand.

 

[Pntbll687]

i would suspect it's coming from the bottom seam somewhere. And yes tanks leak from there.

The solid top on the stand is probably holding the bottom pane in place, making this much more manageable. Sand or salt creep could have filled the leak temporarily. I would try to confirm as best you can where the leak is coming from, or get some pics up if you can. I would hate to see you break down and transfer a tank for a leaky bulkhead.

 

[Mastiffsrule]

I put paper towel everywhere I could and watch for them to get wet. It helps narrow down.

 

[JDtimk]

i would suspect it's coming from the bottom seam somewhere. And yes tanks leak from there.

The solid top on the stand is probably holding the bottom pane in place, making this much more manageable. Sand or salt creep could have filled the leak temporarily. I would try to confirm as best you can where the leak is coming from, or get some pics up if you can. I would hate to see you break down and transfer a tank for a leaky bulkhead.

it's definitely not coming from the bulkhead. I cut out a nice pie shaped area when I built the stand so that I could work on the bulkhead easily, so I can see its not the bulkhead leaking.

I put paper towel everywhere I could and watch for them to get wet. It helps narrow down.

I can see the spot where it is dripping out from under the tank in between the stand and bottom of the tank, so I know its coming from the bottom of the tank, but I don't know if its a seal or a crack or what. I guess I was hoping for some thing fixable that I hadn't thought of lol.

 

[Mastiffsrule]

Let’s hope for the best outcome.

I empathize with you. After I lost 10-15 gallon on my floor 2 weeks ago I guess I have a vendetta against bulkhead

 

[sharpimage]

I would drain it. Not worth 120 gallons on the floor. Get a replacement and switch them out

 

[Dom]

I think draining the tank is the only way to go. If you repair or replace, you have to drain it... right?

I'm on board with replacing the tank.

 

[jtl]

^ Only way to go.

 

[Erica-Renee]

Last summer we had a tank do exactly the same. water under the tank at one area.. It was not close to bulkheads or plumbing. I though maybe it was splashed out.. A Few days later it happened again . then the next morning we were sitting in here drinking coffee my wife says I hear something dripping.. We muted tv and followed the sound..The floor under the tank and down into the basement was soaked. I went following the water and sure enough it was coming from the BOTTOM SEAM.. This is where they almost always leak from...
We immediately put our emergency plan into action.. (Brought inside from garage the 200 gallon pond tank) Drained the tank moving live stock and rock work all at once. We called and bought a new 240 the same day..... Rebuilt the old tank and its now our sump..

Our old tank was around 25 years old this seems the average life of the silicone to glass due to sand getting under and working it loose...

GOOD Luck and ABOVE ALL DO NOT WAIT... we had no damage because of unfinished basement under the tank (by design ) you might not be so lucky.

 

[JDtimk]

Thanks for the feedback everyone. Luckily the tank is in a "fishroom" in the unfinished basement so the leaking water would not be welcome by any means, but it wouldn't be in the living area of the house.
I looked around for replacement tanks today and so far what I want and what I can wait for and what I can afford are three different things lol.
I want a 4' x 4' tank but of course that would be custom made and take a month or two to get and be around $1700 or so. My second choice would be a DD 250 gal tank which is 6' x 3' but that is $2000+ so a bit more than I wanted to spend. Third and a distant third at that is a 180 gal 6' x 2' non reef ready that I would have drilled for an external BA style overflow for about $1100.

 

[JDtimk]

So I guess I will continue this in a build thread, I hope... There is a part of me that wants to throw in the towel after an event like this but I am not sure what I would do with all my new found free time and extra money if I gave up reefing..