[katiejo77]

Get some Vaseline and rub it liberally on the main gasket that goes around the lid. This will likely solve the issue.

I hadn't tried that initially because it wasn't leaking on all sides, but for the sake of elimination I went ahead with that test. I made sure the lid was totally emptied of water, the hoses were drained, and there wasn't enough water in the canister to push through when sealing the lid. I reattached everything, pumped the siphon once, and waited for the water to get through. It made it to the output and held for about 15 seconds before it started leaking again. It's only leaking out of the handle closest to the disconnect valves, and it's happening whenever the pump is primed, even if it's not plugged in.
Any other options to try?

 

[katiejo77]

Is this a continious leaking or is it by any chance only when it first starts? Most canister filters (including these) will get rid of excess water that overflows the lid by coming out the side like you describe. If it keeps doing it as a constant stream then clearly that's not it. But if there is only a few drips and then it tapers off that would explain it.

Otherwise, unfortunately I'd say you have a bad gasket or a cracked piece of plastic somewhere.

It seems to be a constant leak, as I've let it go for a few minutes without it stopping or tapering off. I suspect it's probably cracked plastic as I may have over-pumped the primer the first time I got it going. I may try a new gasket as that's probably the cheapest part swap I can do, but if it's actually cracked plastic I guess there's not much to be done for it. 😕

I had two of those similar filters under a different brand name (Grech GW-304B).

Check to make sure all the media baskets are seated properly! That was the issue with one of mine. Stack all the media baskets on each other while they are out of the filter case, so you can see that they are all stacked properly. I had slightly overfilled one of my baskets with media, which prevented the others from seating properly.

I have a few filter pads in the bottom basket, but the upper baskets are currently empty. When I got it off craigslist, that's all it came with. Would it cause problems to run it without any filter media? Like, do the baskets float up or something?

It's FIXED!! Thank you to everyone who offered suggestions! It ended up being the main gasket. I wrapped plumber's tape around the lid 2x, then replaced the original gasket over top of that. No more leaks! I hope this helps someone else, too. I was ready to throw in the towel!