Jump to content
SaltCritters.com

Hairline crack on inside of tank?


cocojakes

Recommended Posts

Okay, so I'm setting up a new 75 gallon tank, I drilled 3 holes in the back, one of the holes (I didn't notice when drilling) but when I was about to paint the back, the hole in the bottom right corner of the tank, has a hairline crack going from the edge of the hole, to the edge of the tank. Only on the inside though, it looks like a crack, but doesn't make it all the way through the glass. I can't tell how deep it is though. It looks no deeper than a scratch, but its putting me on edge. Is this a recipe for my tank exploding in the middle of the night one day?

 

If it was cracked all the way through to the other side of the glass, I would for sure be buying a new tank, but this is almost just like a scratch. I can feel it on the inside, but not the outside, and I can't see the crack in the glass, it appears to just be on the surface. but I know its not a scratch, its for sure some kind of stress crack from drilling. could it just be a long thin chip that came off from drilling?

 

Its also now that I think about it, that could cause a leak now, because theres a tiny channel for water to travel under the gasket of the bulkhead. I really don't want to drop another almost 200 dollars on a new tank.

 

You can't really tell much from the pics, but they at least show you the location, and how jittery I was with the drill lol (the scratches on the outside of the tank around the hole)

 

 

11828770_10155902941145346_6313022979029

11792130_10155902941140346_7874965660298

11054847_10155902941125346_4428444373936

Link to comment
Murphs_Reef

I had this same issue on a smaller tank (15g), right at the bottom. Rub in some silicon, fill it with water in an area you don't mind getting wet, in a shed maybe, leave it a few days n check... Should be fine. But check first so you don't end up killing every thing in the tank and buggering up your living room!

Form the last pic I would say it's a pretty shallow crack but...

Link to comment

as far as I can tell, it barely scratches the surface, normally you can see a crack in the glass if you look at an angle, I can't see anything IN the glass, just on the surface. but it still sketches me out. Do you think some silicone on the inside will help? I can't really silicone the whole thing, because I need to keep the surface clean for the gasket to work properly on the bulkhead

Link to comment

Put masking tape on both sides of the glass before drilling, and you won't get chips and cracks.

I always put a layer of tape on the underside when drilling the glass. This is the first crack I've ever had, I often get small chips (no more than a few mm away from the edge of the hole) but thats to be expected when drilling free hand with minimal experience, never really anything to worry about. This crack worries me though, because its right in the bottom corner of the tank, so it has the most possible pressure on it. Its only a small surface crack right now, but once I paint the back I won't be able to see if it ever grows all the way through the glass, and if it were ever to break, I would be screwed with 75 gallons of water on my apartment floor.

 

Maybe I could replace the back panel, might be cheaper than getting a whole new tank. But then I have to trust my silicone job, which I'm not sure I trust myself building a tank.

Link to comment
Marc.The.Shark

I'd silicone a piece of acrylic across the corner & make it into an overflow at this point, take the stress on it right out of the equation. If it were me I'd always worry it was going to crack & leak. What were u using rhe bulkhead for? It's at the bottom correct?

Link to comment

Yeah its at the bottom right, there are two holes half way up the centre, which will be covered by a centre overflow, this hole was to have a grill attached, and be used for water changes, and to easily drain the tank whenever needed (I'm likely to move in the next year or so, so I've been designing this system with that in mind, making things easy to take apart into manageable pieces for moving)

 

I considered not making this drain, but opted to do it. Now i'm kicking myself for shooting myself in the foot here. Removing the pressure from the area with the crack won't necessarily do anything though, applying pressure anywhere on a cracked pane of glass can often cause the whole pane to fail. Really my options are trust the glass, replace the back panel, replace the whole tank.

Link to comment

I can't run a bead the whole length of the crack though because it goes right to the edge of the hole, and a bead of silicone will stop the gasket on the bulkhead from making a proper seal

Link to comment

I'm torn between putting silicone as far as I can, and just trusting it since it really seems like the crack is just skin deep, or replacing the whole damn tank, and risking cracking it again drilling the new tank. I could also replace just the back panel, but that would be a lot of work, and I don't trust my silicone jobs to actually hold pressure.

Link to comment

the hole looks poorly drilled and is positioned too close to the edge of the glass. regardless of how small/shallow the crack looks, it is still a crack and will absolutely fail over time. do not try to fix it. replace it. I have built/drilled dozens of tanks over the past 15 years and I would never trust any tank with a crack. you have ruined the structural integrity of the glass and added water pressure will result in failure. patching with acrylic and silicone is a horrible idea because silicone doesn't bond to acrylic. again - buy a new tank.

Link to comment

How is the hole too close to the edge, its just over 2 inches away from both edges of the glass (the trim covers a good inch of glass) I'm going to fill the tank with water, without doing anything to the crack, to see if it expands at all (goes deeper into the glass) if it does I'll be forced to replace it. I'm just so resistant to throw 200 dollars out the window.

Link to comment

Best practice is to drill any hole so that the edge of the hole is 1.5x the diameter of the hole away from any edge. example - drill a 2" hole, 3" away from any edge. at the very least, 1x.

 

It also appears that your hole was not drilled straight, but rather at an angle.

Link to comment

I'll consent to the hole being drilled not ideally, I was standing on the couch trying to get up high enough to drill the end of a 4 foot long tank stood on its side. The bit jumped a bunch before I got a good hole going, but its as strait down as any other. The hole I drilled was for a 1 inch bulkhead, so 2 inches is within the 1.5 times rule. I really am quite baffled at the crack, because it looks like any other crack, but as far as I can tell is only surface deep, which is confusing.

Link to comment

I looked at the photos on a real computer and it looked like the hole was drilled at an angle, but it was just the scratches from your bit dancing around. 2 issues that could have caused the crack - the stress of the bit dancing on the glass and not having a constant stream of cool water running over the bit and hole. I'm assuming you didn't use water because you said you were standing on your couch.


Also, the 1.5x rule is for the hole size, not the bulkhead size. so if the hole is 2" in diameter, was it drilled 3" away from any edge? sorry if that was clear the first time.

Link to comment

no, I used water. I taped underneath with painters tape to catch the bit, and had a towel down in case the tape failed to catch the falling disk. I kept the drill bit constantly wet with a spray bottle of cold water, and paused periodically to clean up the glass mud. Went super light at the end, barely even the weight of the drill. I have no clue why it would crack like that, there were almost no chips

Link to comment

Ideally you want a constant flow of cool water. if the friction heats up the glass too much it becomes more prone to cracks.

 

keep in mind that each tank could use different quality of glass, even from the same manufacturer. I'm leary of quality control from certain companies. it's possible that it's just cheap glass and it couldn't handle the overall stress from drilling.

Link to comment

Also, the 1.5x rule is for the hole size, not the bulkhead size. so if the hole is 2" in diameter, was it drilled 3" away from any edge? sorry if that was clear the first time.

No that was clear, I used a 45mm drill bit, which would mean 70mm which I'm just shy of.

 

 

I think I'm gonna test it with water, if it doesn't worsen after a day or so of full water pressure, I'm gonna treat it like a scratch, put a bead of silicone for good measure, and trust it. If it worsens I'll be forced to drop the $200 on a new tank, and likely a second hole saw since this one is getting warn down after 3 holes through the thicker glass

Link to comment

Silicone won't do anything. and testing it with water for a few days won't tell you how the crack will react with sand, rock, etc in it.

 

But if you insist on still setting it up, be very careful of any plumbing you hang from the hole as the weight will also put stress on the crack.

Link to comment

The hole was designed purely as a drain for water changes or emptying the tank, so it will only have a short piece of pipe, a ball valve, and then a union for easily attaching a hose. And realistically rock and sand shouldn't affect it much.

Link to comment

You should be fine. I broke the whole back piece of glass on an old 18g cube and replaced with new.glass and dod.silicone myself. Didn't look pretty but worked. If you put silicone inside the Crack and smear it in good you should be fine. That looks almost like a scratch.

Link to comment

Silicone won't do anything. and testing it with water for a few days won't tell you how the crack will react with sand, rock, etc in it.

 

But if you insist on still setting it up, be very careful of any plumbing you hang from the hole as the weight will also put stress on the crack.

 

I agree.

Link to comment

Archived

This topic is now archived and is closed to further replies.

  • Recommended Discussions

×
×
  • Create New...