Why does my glass versa-top keep cracking?

[Luananeko]

This is my second lid so far that has cracked on my 75 gallon tank, and in exactly the same way as the first one. The first time I attributed it to the fact that I was doing a lot of re-arranging of filters and I thought I must have mishandled it since both halves of the lid broke the same way... But after I replaced both halves last week I've already found one half of the lid is cracked again, with the exact same crack. Any ideas why?? It's a $40 top so I'd like to know what the heck's happening before I waste any more money on fixing it...

I've attached a pic. I scooted my light fixture forward for the picture of course... Would it be the heat from the light maybe?

 

[mfdrookie516]

Sounds like a great reason to remove them... along with the increase in gas exchange. Glass tops with the plastic strip behind them are a recipe for disaster IME. pH crashes caused by poor gas exchange are not fun.

As to why it keeps cracking, that's odd. Is the light sitting ON them or just ABOVE them?

 

[Sake]

Is there anything sitting on the trim of the tank? Pebble, caulk, or anything that could be putting all the weight on one part? Pretty sure that light doesn't produce enough heat to crack glass like that but I can't say for sure.

 

[Duddits]

I don't think heat from your light would cause it to crack. There has to be some kind of weight put on it for that to happen or something dropped on it. I would recommend just removing them. I've had more success with open top tanks. Like he says above, less worries on gas exchange, oxygen and heat trap

 

[Luananeko]

Sadly removing them isn't an option... I have frogs and a betta and soon a red tail shark that all like to jump. The light rests on the rims of the tank, which puts it about a third of an inch above the glass.

 

[Sake]

Perhaps you could make a screen top?

 

[Fishandmusic81]

+1 on the screen top it could probably be cheaper than the glass top and allows gas exchange 

 

[Luananeko]

Oops, missed the question about it resting on anything... Nothing that I can see, the rims are all clear and the wires and pipes have their own cutouts.

A screen top is a good idea, I didn't even think of that... Are there any good DIY guides to make one? I'm not the most handy person....

 

[Sake]

They sell screen kits in most hardware stores for fairly cheap, just have to figure out the materials you can use in an aquarium. Should be fairly easy to construct.

 

[Duddits]

You can buy a pre made screen top that has metal edging that will support the light

 

[Luananeko]

You can buy a pre made screen top that has metal edging that will support the light

Ooo, that would be ideal. I'll do some looking around to see if I can find any that fit my tank

 

[friscuba]

I find this odd. It really seems that there's got to be some topside pressure on the lid. Stupid question... do you have a cat? It wouldn't be the first time a curious visitor caused a broken tank lid.

 

[Luananeko]

Yes, I have two cats, but neither have ever jumped on top, and especially not from that side. If they jumped up it would be from the other side. Every time they're watching the fish they stand on the end of the bed and lean out to put their paws on the stand next to the tank.

I talked to my LFS where I got the lid and apparently they have this happen all the time when the lights are too close to the lid. Exact same crack pattern as I have, and the crack is centered under the light, so that seems to be the most likely culprit.

The tank keeps creeping warmer than I'd like anyways, so it seems like a combination of raising the light and using a screen top is going to be the solution... All of the screen tops I'm finding are for reptile enclosures though... Would they still work on my tank, or would they rust?

 

[Terrance]

I recommend using ceiling eggcrate panels. You can cut them to fit perfectly.

 

[Luananeko]

The eggcrates look like they block way too much light for anything not directly below the fixture... I like the idea of the screen top so as much of my light still gets down to my plants in the back corners as possible. I already had to move some of my cabomba out from the corner because it just wasn't getting enough light to really thrive until it got from under the corners.

 

[BlaseMrNiceguy]

The ceiling egg crate panels he is talking about are made for light fixtures they are the ones you sometimes see over fluorescent fixtures they are almost clear to look at up close. I like that idea as you wouldn't need to remove your lid to feed.

 

[Luananeko]

I'd still need to lift the lid for feeding since I feed frozen with a turkey baster and have to hunt down my frogs for hand feeding... The egg crates may look clear, but have you seen the flourescent office lights without the eggcrate in front? They're about 2x as bright. Eggcrates were created as light diffusers so people wouldn't be blinded by the flourescents. A screen lets far more light through IMO.

 

[rkilling1]

The only thing I can think of is the way you have the back plastic connected to the glass. You should remove the plastic that sits on the aquarium. By leaving the plastic on the bottom half, now all you have is two places where the top is resting on the aquarium. The top should be resting on the entire top of the aquarium, not just those two areas.

That me see if I can better explain this...

The plastic is clamped onto the glass by a 'c' looking channel. That channel raises the glass up where it contacts the aquarium. You should cut off the bottom portion of the channel where it sits on the aquarium.

 

[Luananeko]

Ahh, that makes much more sense than the heat idea... I've put my hand by the glass and it doesn't feel hot enough that I'd think the glass would crack... The pressure from the plastic end piece I could see causing stress though as it was a pain to put on.

In either case, I found a great DIY tutorial on how to make your own screen top, so I think I'll still go that route. Better gas exchange, less light diffusion, more durable, and doesn't keep trapping too much heat in the tank, so it's all around a better solution. Here's the link if anyone needs it http://www.3reef.com/forums/i-made/clear-mesh-jump-stopper-121802.html