Crazing in big tank

kyleboldy2003

Black Skirt Tetra
Original poster
MFK Member
Dec 16, 2014
5
3
18
detroit
I just bought a 8 foot by 4 foot by 30 inches tall tank. The tank has been sitting for around a year. I have not filled it with water. There is crazing through your the whole tank. I think the stand was in level it is 3/4 inch thick all the way around and top is 1 1/4 inch.. just looking for some opinions thanks.

B64CF924-D1B9-4BBD-9E5E-317A6EEA91D3.jpeg

F1F97744-8995-4022-AE28-F90444546B88.jpeg

EF80E22C-589D-4E7D-87AB-2A83AB9D8BD6.jpeg

B08B34AC-6580-4A8A-A89B-C0DDA8786142.jpeg

6CF4834D-D007-476C-868F-52C0D37B73AC.jpeg

9AFA6ED3-E2A8-4102-B650-B45F2F34A998.jpeg

C3D8F5E7-8DEF-4784-9A9C-F53495D208C2.jpeg
 
  • Wow
Reactions: Proteus

Proteus

Polypterus
MFK Member
Nov 2, 2008
1,107
108
96
Never seen anyone's acrylic when the crazing this bad. That includes the sheet itself.
 

Blakewater

Dovii
MFK Member
Apr 27, 2018
458
706
105
25
That looks highly likely to break. if you choose to test it I would not ever fill your tank past 2/3rds full. Whoever built that did a cheap job and probably used acrylic too thin for the height. Ive seen a lot of crazing and usually its pretty common but to the extent it stretches that tells me the acrylic is literally only held together by the seams and cant handle the water pressure itself.
 

esoxlucius

Redtail Catfish
MFK Member
Dec 30, 2015
1,681
2,898
154
UK
I work in plastics recycling and we get sheets of acrylic in from time to time. I've often done weighted experiments on the sheets to see how far they'll bend before breaking. When you reach a certain critical point you can see crazing appear in the bend area, very much like in your pictures. And because acrylic is so stiff it dosen't need to be bent that much for stress marks (crazing) to appear.

It could well be, as someone's already said, that it is a diy tank which has been made using material with the incorrect thickness. If they were doing regular fin level water changes for example then the ebbing and flowing of the acrylic as the tank emptied and then filled again could have led to those stress marks over time.

It's a real shame you didn't post pictures before you bought it. I dread to think how much you paid for an acrylic tank that big, even a used one. Ouch!
 

Lepisosteus

Potamotrygon
MFK Member
May 20, 2014
3,387
2,499
164
Ontario, Canada
Yikes. 3/4” on 3’ height over 8’ span is definitely thin. Should be at least 1”. I would have passed on this one.
 
  • Like
Reactions: esoxlucius

ReApEr666

Plecostomus
MFK Member
Dec 15, 2018
117
195
51
34
It’s 30 inches tall. Could I just fill it up to 24 inches and it would be ok??
Just looks like a very old tank to me...def. showing all the signs of being 30+ yrs old. Even looks to have been “tip and poured” when it was built on the inside seams. I own/run a few similiarly built tanks from that era of construction. Biggest worry/concern is that one seam. The “crazing” is all just yrs of water pressure and common to find for the age. You can tell by the color of the acrylic also and that extra thick/laminated top. They dont build em like that these days.
Since its already reinforced on the inside and theres some cracking in that reinforcement id put a patch on the outside of the tank running the height of the tank/seam. I prefer weld on #40 or #42. You will only need a pint and some scrap acrylic. Use a strip of material 2-3” wide covering the entire seam top to bottom and atleast 1/4” thick. This will ensure if the inside seal is comprimised the tank will still hold water with ur new patch/seal.
Yes, not filling the tank to the top will relieve some of the water pressure but i would most def. still do the outside patch on the problem seam and if any other seams look like that. For the cost of materials its well worth it. I run my older tanks around 4” from the top brim. Easy enough to redrill acrylic to lower the water level or cut an overflow box if needed.
 
zoomed.com
hikariusa.com
aqaimports.com
Store