Really frustrated and need advice

Hello, this is my first post and hopefully not last. I am so frustrated with my two axie tanks im actually thinking of selling them even though I and my kids love them. Here's the situation.....

I have two tanks, a 20 long and a 15, each with one axie. The tanks have been running for a year and a half and have run with the current canister filters for over a year. Filter sizes are plenty big for the tank sizes, temperature is right, levels are fine, critters seem happy and healthy.

My problem is that the filters slime up to the point I have to do a thorough cleaning every single week to keep the water flow from stopping, literally. More than about 7 or 8 days and the flow nearly stops. Which then requires cleaning everything including the tubing.

This can't be normal. I'd love thoughts and advice. Thanks!

Do you have a sponge over the intake already? I found that to be pretty helpful in reducing slime buildup, also making sure to use 2 layers of sponge in the first section of the canister helps catch the gunk before it can clog too much.

^That's a good one.

I'm not sure why the slime would come so aggressively. I can only think of three reasons:

When you clean the filter (which you now do every week) - how do you do it? If you do a real "deep clean" every week (chlorine, boiling water, really scrubbing hard, etc.) that will probably mess up any bacteria population in there.

Is there any "active" material in the cannisters - chemical filtration or even just activated carbon? Those do wear out after some time and might need to be replaced.

Could there be a slime colony somewhere else in the aquarium, somewhere in a dirty corner or under some rocks? That would at least explain where the new slime comes from after each clean.

I have Fluval canisters so the spices are on the side, but there are four of them and all get slimed up. The only other thing in the canisters is bio filter media. I have an inline UV filter on one of the tanks but not the other. The water in both tanks is clear.

I haven't tried a pre filter so maybe I will give that a try. My cleanings are not deep so no chlorine or boiling, just scrubbing of all surfaces and tubes. Maybe I'm changing too much water each time? Could that make a difference?

Thanks for the ideas!

Also, how often do you change out your sponges in the filter? I’ve just been rinsing them out in tank water but never changing them out. That's what I do with my fish tank and it works great. But in the axie tank they get complete clogged.