Epoxy
 

The dome on my DE pool filter cracked. Crack is about 1 ft long. The seam is tight (no light shining through) and it could take a bit of time before the home warranty contractor gets a hold of a replacement.

I was thinking of a temp fix so I can get pool filtration going again. I do not want my water to foul. What ever the fix is, it needs to be water proof, be able to with stand pressure up to about 20 PSI and bond to plastic.

DE filter housing is similar to this.
https://www.poolsuppliessuperstore.com/hayward-de6020-pro-grid-vertical-de-filter-60-sq-ft

Any recommendations on a easily obtainable glue/epoxy or a different idea on a fix?

Thanks

JB water weld. I used it on my hot tub heater pump housing (cracked and leaking) and it's been holding up great.

edit: it also bonds underwater, and is obviously waterproof

Adhesive
 

I have used JB Weld for decades but have now switched to this stuff, incredibly strong:

https://www.zoro.com/loctite-adhesive-cyanoacrylate-08-oz-gel-2267079/i/G3375333/feature-product?gclid=EAIaIQobChMIpInyyN662wIVyjyBCh2TJQgWEAYYAyABEgJ2D_D_BwE

Marine-Tex
 

I tried JB weld and it was an epic failure. I think because it was more of a paste verses a liquid. The crack I am filling is about 1 ft long and I dont think it could flow in and bond. Back to the drawing board.

Have you tried model airplane glue? It melts the plastic and welds it together very well.

3M 5200 in white. I used it to mount outdrives to transoms. Will never fail.

Whatever kind of glue you use, you're going to need to reinforce it with a mesh or tape of some variety. The normal operating pressure of a pool filter is 15-20PSI which doesn't seem like a lot until you consider that you have that much force pushing on the entire wall of the filter attempting to blow it apart. Glue alone isn't going to do it, the force pushing it apart is enormous without some sort of reinforcement.

Mesh or no, it's tough to mend a crack in a pressure vessel from the outside. Can you get to the underside?

Check with 3M. They make tape for all kinds of applications.

Not sure if this plastic will melt.
Not sure that is thin enough. The crack is very tight and a thinner liquid might penetrate better than a thicker adhesive.

Do you have a recommendation for a mesh?

Yes. The dome comes apart and I can get access no problem. I used a orbital with 80 grit to scuff up the seam
I have a very tight angle on the inside. tape is going to be a PIA in that angle.

Can you epoxy a flexible plastic to the outside, fill the crack, then reinforce with flexible plastic inside?

Probably not. There is a pronounced rib on the outside and the crack runs straight down the side of it.

https://www.harborfreight.com/plastic-welding-kit-with-adjustable-temperature-96464.html

Plastic welding could work but may embrittle the plastic.

The 5200 would hold but I would drill the ends of the crack with an 1/8” bit to stop it from growing then clean it with alcohol or a wax remover before applying a bead and spreading it evenly across the crack. Let it cure completely before use. If you do this to both sides it will hold.

Fiberglass?