hard water sponge filter issues…

[OldFishKeeper]

Ah, I didn't realize it was a corner filter. No problem, I have a number of Aquarium Coop sponges that can be easily modified and would improve them a lot. Thanks again...

 

[bgarthe42 59]

I, too, like the squared off two sides to put in a corner keeping fish from wedging themselves between glass and foam. And, in so doing, it would take up less space and be less noticeable. May have to order a few although they are not my primary method of filtration.

 

[OldFishKeeper]

I, too, like the squared off two sides to put in a corner keeping fish from wedging themselves between glass and foam. And, in so doing, it would take up less space and be less noticeable. May have to order a few although they are not my primary method of filtration.

I agree with that, for adult sized, community fish.

For my fry rearing tanks, I prefer to have the standard, round sponge/prefilters away from the sides and corners. Matten Filters on the ends and as dividers would be my choice here.

 

[Bozsy]

I've had a very similar situation in a shrimp tank in hard water, and it's almost certainly not a weak pump, but rather a gradual build-up of fine pores in the sprayer or the air inlet itself in the sponge filter. Calcium and biofilm really build up slowly there, and you don't see it until the flow drops almost completely.
In these conditions, it's not so much a different brand as a different type of air supply that works better: sponge filters with a larger diffuser or replaceable air stones that can be easily washed or replaced. Some aquarists simply keep a few replaceable sprayers and rotate them instead of cleaning the entire filter each time.
Another point is that the smaller the bubbles, the faster the outlet itself will clog, especially in hard water. Slightly coarser aeration often works more consistently in the long run, even if it looks less pretty.