Spontaneous Sump Crack

[mattytatt]

Hello Ya'll,

I woke up this morning to my sump dumping water into my cabinet and can't figure out how it happened. I have attached some pictures and would appreciate any ideas as to what the culprit was.

Sump setup:
20 G Aqueon long (Glass) with 4 acrylic baffles cut to fit. The intake has the pictured protein skimmer which normally sits on eggcrates. The middle section has the pictured clip-on light with chaeto, live rock rubble, 2 heaters and enough sand to cover the bottom. The final section has the pictured return pump and a Tunze ATO. The tank has been up and running for about 2 months now with a small CUC.

The only thing that I can think happened is I bumped the light a few days prior and the crack grew but I am entirely stumped.

Thoughts?

Thanks
Matt

 

[mcgyvr]

my guess... acrylic swelled and put too much pressure on the glass..
How tight were the acrylic panels.. Acrylic panels need to be 3/16" to 1/4" smaller than the interior dimensions to allow for expansion..

The glass on those tanks is really thin and it doesn't take much to crack them.. as you have found out..

 

[NewOne81]

Looks like the crack originated by the clip on light. I suppose bumping the light hard enough could cause the trim to flex and fracture the glass. Then the crack could have just continued out from there

 

[GimpyFin]

+1 to what mcgyvr said. IMO, I'd use glass for baffles instead of acrylic because it does swell.

 

[thegrun]

+2, use glass on glass tanks, acrylic on acrylic tanks. In addition to the swelling issue you really can't get a Sri g glass to acrylic bond.

 

[mattytatt]

Thank you for all the helpful posts! It does appear that the crack originates from the acrylic baffle... It was an incredibly tight fit originally and I didn't leave any room for expansion.


Thanks
Matt

 

[mcgyvr]

It was an incredibly tight fit originally and I didn't leave any room for expansion.

Lesson learned..

 

[billdogg]

On the next one, have a local glass shop cut 1/4" glass for you, but still cut them a bit small - maybe 3/16 or 1/4 shy of the total width. It will make placing them much easier. Have them smooth the edges as well. It is probably cheaper than acrylic anyway - I know it is here, and they (my local go-to glass shop) will have them ready same day.

Oh - and petco is having another $1/g sale!!!

 

[ziggy2]

Make sure that the baffles are not tight. The silicone will make up the difference. Besides, on a sump, if it's not water tight, it's not going to matter.

 

[thegrun]

I would go with a 1/4" gap on both sides (1/2" smaller overall). Be sure to use a good quality structural silicone, I like Momentive RTV silicone. You also want to let the silicone cure for at least a week before using it. Be sure to have the glass shop sand the exposed edges smooth for you if you are not familiar with polishing the edges smooth yourself.