Acrylic tanks bulkhead hole patch up--too many and wrong side

[wooden_reefer]

I have a blue background 180 gal 8 foot acrylic tank. It was used as the sump to a 300 gal acrylic display tank. I have both. The acrylic thickness is half-inch for both.

The previous owner drilled holes of various sizes bulkheads on both tanks, the smaller tank into the front clear front (very wasteful). This is absolutely unacceptable and has to be fixed. I hope to patch up resulting in as little distortion as possible. I will use a smaller sump (a 80-100 gal of epoxy plywood or glass tank for sump) for the 300 gal tank and use this old sump as another display tank.

For the 300 gal tank there are too many holes but of course were drilled at the back. The owner drilled 3 inch holes for combined circulation. I believe that for filtration the flow need not be as high as for internal circulation, and to save energy the two flows should be separate. So I want to patch up excessive holes.

These holes are 1.5 to 3 inches diameter.

I want to use use weld-on 4 and/or weld-on 16. I have a stroll saw so I plan to cut disks of the correct size, from a sheet of 1/2 in thick acrylic. may be the disks should be very slightly tapered. I may tilt the scroll saw table 1-2 degrees.

I am thinking the weld-on 16 can be too thick (viscous) and weld-on 4 can be too thin. So may be a mixture of two would be the best. Or would weld-on 16 alone will seep through the cervices and gaps, provided that the disk is no more than 1/32 smaller than the hole?

If you have done this before and have insight please help.

Thank You

 

[on the spot]

...The previous owner drilled holes...and has to be fixed. I hope to patch up resulting in as little distortion as possible.

I'd suspect a clean edge and a nice fitting plug would give the best results. I'd abandon the scroll saw for your router.

I'm not hopeful it'll work well.

 

[wooden_reefer]

I'd suspect a clean edge and a nice fitting plug would give the best results. I'd abandon the scroll saw for your router.

I'm not hopeful it'll work well.

Thanks I have a router table but cutting by router I cannot get a slight taper.

I am not sure whether a tapered plug is a good thing.

 

[Dr RBG]

Precise fit

Precise fit

You would need a very precise fit between the two pieces. They would have to be polished also for the weldon to work. Could you glue a flat piece over the holes so you were gluing 2 large flat surfaces? Post some pictures of the holes if you can.

 

[Sk8r]

My advice would be a plain ugly flat plate, no try at fitting it. If it shows from the outside, set a rock in front of it and ignore it.

 

[billdogg]

My advice would be a plain ugly flat plate, no try at fitting it. If it shows from the outside, set a rock in front of it and ignore it.

^^^This^^^

Really, the only practical fix IMO.

 

[on the spot]

What have you decided to do?

Can you hide the repair or plugged bulkhead with trim? Like a wide frame around the tank maybe.

Hope to see what you come up with.

 

[lapin]

I would order Sci Grip 40. You will need to tape one side so the mixture does not flow thru.
It will shrink a little when it dries. To prevent bubbles, the tape side needs a bit of space for some extra to make a fillet of sorts. You can do this by taping around the hole. Once you insert the plug, tape again this time over the whole thing, but dont press the tape down into that gap. This should leave some space. If you think it has trapped air you can poke holes in your tape with a pin to let air escape when the liquid fills the joint. You can apply it with a syringe. Once done you can sand and buff off the excess. Making a clean visual joint will be hard if you are not used to working with acrylic and bonding agents.