Is It A Scratch Or A Crack?

[Rynofasho]

So I'm eyeing my second hand 75 I got. I know it holds water as when I looked at it it was still running. Now that I've cleaned it and am REALLY looking, I see some spots on the glass that appear to be a bit -- Im not sure what to call it -- maybe deeper than some of the other scratches in the tank. They catch the light. I, being paranoid, am worried. I can feel the scratch when I run my nail across on the inside, but cannot feel it on the outside. Should I be worried if I can feel it? What are my options? I dont want to go putting silicone sealant all over this thing, but I also don't want 75 gallons of water on my living room floor. Any good rules of thumb about what is safe and what isnt?

 

[micko]

If you can only feel it on one side its only a scratch, IMO

 

[Smells a bit fishy]

if you are worried, you could always see if it grows at all. Maybe mark the 2 ends of scratch to see if it grows over time. If it doesnt then you have peace of mind that its safe

 

[bristlenoseitplecoman]

that is the thing about second hand tanks. they have scratches and such. I would call it a scratch.

 

[Rynofasho]

Ok thanks. Would it be a good idea to take a small bit of silicone sealant and spread it on there with a toothpick and just wipe off the excess or just leave it

 

[Mowbz]

Ok thanks. Would it be a good idea to take a small bit of silicone sealant and spread it on there with a toothpick and just wipe off the excess or just leave it

As mentioned above, try marking the two end of the scratch/crack on the outside of the glass, fill it with water and leave it a few days. If it spreads, you know its a crack.

As im a sucker for "testing things" i personally (i say this as this isnt a suggestion, just what i would do) would take it outside, mark the scratch, fill it with water only, and give it a few taps in the area of the scratch/crack. (Nothing over the normal knocking you would give the tank during maintenance) The pressure from the water provides constant outward pressure, so if it splits and loses its water, it was a duff tank, and i would be glad it didnt get as far as being set up in my house.....

Again as above, this is the way with second hand tanks. They're a "better buy" guaranteed, but you can never guarantee the quality.

All the best!