Advice, ideas on repairing acrylic tank.

[MauiMarineAquarium (MMA)]

Hey guys,
I need advice. I bought a 120 gallon acrylic tank with a built in over flow. Unfortunately the previous owner tracked the bottom of the tank between the holes drilled for the return and drain. My question is what would you do to repair the crack the best. I provided some pictures hopefully the crack shows. I have one idea but I need to see if I’m on the same page Thanks in advance.

 

[kevyg]

Those holes seem a little.... ummmm gigantic ? I may just be missing the scale of them.

 

[kevyg]

I need advice. I bought a 120 gallon acrylic tank with a built in over flow. Unfortunately the previous owner tracked the bottom of the tank between the holes drilled for the return and drain. My question is what would you do to repair the crack the best. I provided some pictures hopefully the crack shows. I have one idea but I need to see if I’m on the same page Thanks in advance.

Needle with some weld on fast set clear water thin is something that is commonly used to bind acrylic.i would put slight pressure from one side and inject the Weld on into the opposite side of the crack so the capillaries can suck in the acetone. Once in, if the entire innards of the seam are not wet all the way through repeat the step reversing which side you inject. You have a total of like, 2 minutes to get this process done, the quicker you are done the better.

 

[MauiMarineAquarium (MMA)]

Thanks for the quick reply. That seems like a better solution then what I had in mind. What I had in mind was to cut out the broken acrylic out. Leaving about 1/2”inch all the way around the bottom of the overflow. Installing a piece of acrylic from the inside on the overflow that’s bigger then the hole. That way the new piece of acrylic sits on the old acrylic and I would use a thicker weld-on to bond the piece together.

 

[pdxmonkeyboy]

if your going to glue over it i would advise to use weldon 16. it is thick like super glue. It will be much easier to get a solid bond as the acrylic is probably bowed.

 

[hybridazn]

if your going to glue over it i would advise to use weldon 16. it is thick like super glue. It will be much easier to get a solid bond as the acrylic is probably bowed.

This is what I was going to suggest. Use 16 to glue over. Injecting into the crack would be ideal but being able to apply any pressure to close the crack would be a pretty tough feat I would imagine.

 

[MauiMarineAquarium (MMA)]

Needle with some weld on fast set clear water thin is something that is commonly used to bind acrylic.i would put slight pressure from one side and inject the Weld on into the opposite side of the crack so the capillaries can suck in the acetone. Once in, if the entire innards of the seam are not wet all the way through repeat the step reversing which side you inject. You have a total of like, 2 minutes to get this process done, the quicker you are done the better.

By the way

This is what I was going to suggest. Use 16 to glue over. Injecting into the crack would be ideal but being able to apply any pressure to close the crack would be a pretty tough feat I would imagine.

i appreciate the input so what I’m going to do first is try what kevyg suggested. I’m going to use thin weld-on , on the crack first. I’m going to use a bar clamp to squeeze the crack closer together and hopefully that will hold.
If this fails then I will cutout the bottom of the overflow and add a new acrylic piece.
Keep the suggestions coming. I really don’t want to cut out the acrylic. Just scared of ruining the tank

 

[Andnosobabin]

Hey guys,
I need advice. I bought a 120 gallon acrylic tank with a built in over flow. Unfortunately the previous owner tracked the bottom of the tank between the holes drilled for the return and drain. My question is what would you do to repair the crack the best. I provided some pictures hopefully the crack shows. I have one idea but I need to see if I’m on the same page Thanks in advance.

Personally unless your going to use the bottom holes (I'd drill new ones for a eclipse or shadow type overflow) I'd glue the crack then take a piece of acrylic and use weld on to glue it over the holes. I think you will like it better than what u have. Plus ur at perfect stage to do so. Just my opinion.

Edit
Didn't see the pix very well so sorry l assumed. But I'd still glue a plate on top and weld the crack and re drill the holes through that u will keep the most strength that way.

 

[Smo]

This is a tough repair. First step is to thoroughly clean the area to get to a contaminate free surface.
I would not rely on simply injecting Weldon 3/4 into the crack. It’s a flood waiting to happen. I would not cut out the damaged section either. Instead, I would attempt to lap a patch over as much of the damaged area as possible (from the inside) with a piece of acrylic the same thickness or better than the existing bottom. Then redrill holes using a jig. Use liberal amounts of Weldon 40, then push the patch down to squeeze out the Weldon 40 to remove air.
Do not use Weldon 16. It has little structural strength.

 

[kevyg]

For the best structural integrity, you don't even need to cut the holes out, use the existing acrylic for extra reinforcement. Lay down a nice thick layer of the weld on then put a sheet over the entire area (a big square of acrylic, not just over the holes, you want the pressure to bypass the center crack. That means the sheet should be basically as big as the taped area.)

To clarify, when I say slight pressure, I am saying just enough to barely bow the plastic, almost set it on a piece of wood that is the size of the distance between the two holes and let the tank's weight be the pressure. Don't have the piece of wood be a giant thick piece, just put a very thin piece of wood under there, this will be a subtle approach.

Hopes my redneck .02 helps!

P.S. I would "score" a box around the two holes (about 1" from the edges of the hokes) with an acrylic cutter or the back of a razor on a utility knife. (as if you were going to try and break cut). That way if the crack decides to be an @$$hole then you have given it a path of least resistance and it won't crack all the way to the edge and cause a whole new set of issues. This is the same concept car manufacturers do with car frames so they crumple instead of just bend randomly in the event of a crash.

 

[MauiMarineAquarium (MMA)]

OK I changed my mind again. I’m not going to try and fix the crack with then weld on. What I am going to do is get thick well Don and use a patch of acrylic and lay it over the holes put some pressure on it and get the air bubbles out. The one thing I’m worried about is cleaning that surface has a lot of calcium and scratches and what not. I’ll keep you guys posted once I get to work on it I need to source well done first I’ll look on Amazon

Thanks
kevyg
Smo
Andnosobabin
Hybridazn
Brian bieger

 

[Smo]

Begin cleaning with a heavy solution of vinegar to dissolve the heavy concentration of calcium. Use a good scraper. Follow that with heavy wet sanding. You don’t need to remove all the scratches. Perform a couple of quick swipes with a clean lint free cloth soaked with a little dentures alcohol to all surfaces to be bonded.
The Weldon 40 is like thick epoxy and will cover a multitude of sins and cure almost as strong as the acrylic sheet. Use it liberally and imbed the patch into it.
Since this area is unsupported by the stand when the tank is filled with water (you need clearance for the bulkheads). The patch will add structural rigidity and prevent a bending moment acting on the seam between bottom and back panels. That would be your next potential failure point.

 

[pdxmonkeyboy]

how tall is this aquarium? its really not that difficult of a repair really.

weldon 40 would be the absolute best but it is tough to find, is pretty expensive, and not the easiest to work with.. and god does it off gas!!

anyways....surface prep is critical, follow the steps above. weldon 16 is just weld 4 with acrylic shavings melted into it but it does not weld acrylic as easy as weldon 4. You dont really need structural integrity, you just need it to seal properly. But given the crack.. better safe then sorry.

So if the bottom piece is flat, flood the area with weldon 4 then drop the patch on top. do not try the capillary action method its too big. hold in place for about 2 min. about 30 min later goop weldon 16 around the entire edge of your patch. Bomb proof.

 

[Andnosobabin]

OK I changed my mind again. I’m not going to try and fix the crack with then weld on. What I am going to do is get thick well Don and use a patch of acrylic and lay it over the holes put some pressure on it and get the air bubbles out. The one thing I’m worried about is cleaning that surface has a lot of calcium and scratches and what not. I’ll keep you guys posted once I get to work on it I need to source well done first I’ll look on Amazon

Thanks
kevyg
Smo
Andnosobabin
Hybridazn
Brian bieger

[emoji869]good luck. Definitely post pics.

 

[Matthew Frost]

Cut a square about 1/8 of an inch smaller than the size of your overflow. Thouroughly clean the inside of the overflow box and finish with alcohol. Liberally apply weld on 16 inside the overflow and drop your "patch" in on the weld on. Make sure it cures, 24 hours should be good then drillyour new bulkhead holes from the bottom up through the new acrylic. If you don't put the holes in the same place you will have a really hard time getting bulkheads to seal bwcause the pressure on the bottom will be uneven.