Acrylic tank repairs

[Derby City Corals]

So when we bought this shop 2 years ago these fish systems came with the store

These systems are over 15 years old and been through a lot

When we first took over we replumbed resumped built new stands bought new pumps and lights and scrubbed every inch of these systems

After 2 years of use and writing on the tanks with paint markers and cleaning with alcohol this is the results

Not sure if the alcohol caused these issues or if this just has slowly gotten worse with time
But I would like to attempt to push them along a few more months

What would be my easiest best course of action?

I was thinking to cut strips of acrylic and use some Weld-on to brace the corners and possibly stop any further spread of the cracks

 

[MnFish1]

Can you feel the cracks from the outside (i.e. with your fingernail)? if not - I do not think puttying weldon on the outside with a strip will help. Additionally, I would think to do any repairs, you would want to drain the tanks completely - and inspect the insides as well. My guess - after all the time/effort, etc - you might be better off buying some wholesale new system or used systems as compared to repairing those (especially if you need them to be active - ie are actively using them in your store).

 

[Malcontent]

Not an expert but acrylic needs a certain thickness per height and those look on the thin side. Too thin and there's too much stress and you get crazing and/or cracking.

I think they're done.

 

[Derby City Corals]

Can you feel the cracks from the outside (i.e. with your fingernail)? if not - I do not think puttying weldon on the outside with a strip will help. Additionally, I would think to do any repairs, you would want to drain the tanks completely - and inspect the insides as well. My guess - after all the time/effort, etc - you might be better off buying some wholesale new system or used systems as compared to repairing those (especially if you need them to be active - ie are actively using them in your store).

Yes you can feel the cracks very well and yes they are all active and full of fish

 

[Derby City Corals]

Yes you can fee the cracks very well and yes they are all active and fully of fish

 

[The0wn4g3]

I would recommend getting vertical corner pieces of acrylic and solvent welding them to the tank acrylic. The key with acrylic is you have to make sure the solvent welds are done properly.

 

[wtac]

Unfortunately the use of alcohol to wipe off the writing is the issue.

IMHO, they are toast and a leak waiting to happen. To "patch" them will be draining, drilling a small hole to terminate the crack so no further "spidering" will occur, fill hole with WO16 and apply vertical strips of acrylic to reinforce the corners. Not going to be pretty looking but it will hold water.