# Is this a crack or a scratch?



## eug (May 18, 2012)

I'm going to repost in this forum for more exposure.

For some background, please check this DIY thread:
Did something stupid - Removed braces

Basically, I just implemented a DIY bracing solution to replace the semi-Euro-braces that were originally in place (partial longitudinal strips of glass siliconed at a 90 degree angle). The aluminum bracing you see is what I added to replace the glass bracing.

On the upper left of the tank, near the left edge of one of the braces, I noticed this:









I can feel it with my fingernail, I can get my nail to hook itself into it, but only on the outside. On the inside it can't be felt. The way it reflects light makes me think it's worse than just a scratch, but a hairline crack that is forming due to a badly designed brace on my part. It could also be a scratch that I accidentally made sometime during the last days when I've been working on the braces. What do you guys think? From a structural point of view, is that a likely place where a crack might form, looking at the way I've attached the braces?

The whole bracing job can be seen here:


----------



## eug (May 18, 2012)

I have found a similar scratch on the opposite side, although this time it can only be felt on the INSIDE of the tank and a bit further into the middle, i.e. it's underneath the aluminium brace. It doesn't seem to make much sense if these are cracks created by pressure stress, you'd expect them to form on the same side, on the outside if anything since the glass wants to bow outwards stretching the outer surface. I'm not talking with any sort of engineering background, it's just my intuitive thinking...

Another aha moment - the clamps I used when siliconing the braces in place are those red C-clamps that you screw tight, and it just happens to be that the marks appear in the region where I was doing the clamping and the marks do not extend further down than the reach of the clamps, i.e. it might have just been a case of too hastily/carelessly removing the clamps rather than cracks that appeared later due to water pressure. Just thought I'd throw out that piece evidence for you guys to consider...


----------



## Geomancer (Aug 23, 2010)

Or the camps were tightened too much?

Best case is deep scratches if you get get your finger nail into them, worst is the start of a crack that will grow over time.

I'm confused though, in the full picture of the top ... I don't see any brace at all going from front to back, just a piece of aluminum along the front, and a second along the back.


----------



## eug (May 18, 2012)

Yeah do check out the DIY thread - basically it's like a partial Euro-brace, like the tank originally had except it's now aluminium instead of glass. The tank didn't come with any sort of cross-brace. Euro-braces work on the principle that the longitudinal braces are strong enough to prevent bowing, eliminating the need for a cross brace.

I did take care to not tighten the clamps so much, I also didn't want to squeeze out all the silicon after all.


----------



## Adamson (Feb 5, 2012)

Nice looking tank! That is definitely a scratch, not a crack, I wouldn't be too worried about it!


----------



## eug (May 18, 2012)

Thanks Adamson! The marks haven't grown in size overnight, so that does make me feel better that it's looking more likely to be just a scratch. I figure a real crack would show some depth cutting into the glass surface that would show when light is shined on it, but I see nothing of the sort.

As for the look of the tank, I'm happy with it apart from the fact that I currently have it totally covered up by my boring black plastic light hood, so I can't even admire my work! After a few months of checking that everything's ok I'd like to further mod the lighting so that the T8 ballasts hang over the tank and the tank itself can be open topped like in the pic above. Maybe I can somehow mod the current hood and add some hardware to it so it can be hung, and give it some aluminum trim to match the tank.


----------



## Adamson (Feb 5, 2012)

eug said:


> Thanks Adamson! The marks haven't grown in size overnight, so that does make me feel better that it's looking more likely to be just a scratch. I figure a real crack would show some depth cutting into the glass surface that would show when light is shined on it, but I see nothing of the sort.
> 
> As for the look of the tank, I'm happy with it apart from the fact that I currently have it totally covered up by my boring black plastic light hood, so I can't even admire my work! After a few months of checking that everything's ok I'd like to further mod the lighting so that the T8 ballasts hang over the tank and the tank itself can be open topped like in the pic above. Maybe I can somehow mod the current hood and add some hardware to it so it can be hung, and give it some aluminum trim to match the tank.


Take off the top! The tank you have would look much better without any top on it. I have a 58 Oceanic that is rimless (looks like 57 illuminata if you google image that) and it looks great. I have it planted, and what I use as far as lighting is simple clamp lights from Home Depot. They cost me I think $8 a piece and do a great job.


----------



## eug (May 18, 2012)

Clamp lights eh? What kind of lighting is it, CFL, T8 tubes...?


----------



## Adamson (Feb 5, 2012)

eug said:


> Clamp lights eh? What kind of lighting is it, CFL, T8 tubes...?


You can put whatever standard bulbs you want in. I basically have two of these clamped to the sides of the tank 75-Watt Incandescent Clamp Light-CE-200PDQ at The Home Depot
And then I put in some "Natural light" bulbs that are super bright. They are CFLs but not the kind that do the little wrap around thing, they look like regular light bulbs. Everything is going well.


----------

