Have any of you other Hydro-sponge users.....

[Regalblue]

tried this - sliding bio-rings over the airline in your lift tubes?

How has it worked for you?
(photo courtesy of CadMan2000)

[JeffroM]

Worked doing what?

[Ron]

Worked doing what?

I would presume providing additional biological filtration.

I have some rings (fluval ones perhaps?), but it seems it'd just be easier to use a second sponge if I really needed the added filtration.

I also suspect the value isn't as great as you'd get using it as media in a larger filter housing of some kind. The water velocity through the airlift tube is high, while you want slower velocity typically for bio-media.

Do the rings slide off easily when the airline is detached?

[Regalblue]

Worked doing what?

exactly as Ron stated

The rings are on the airline somewhat tight, but I suspect after time they will loosen up.

[JeffroM]

I assumed you where going for some other result than adding to the bio filter as it doesn't seem like there is enough benefit for the hassle. 

[Regalblue]

It really wasn't any hassle as I was already running new line and all.

I just figured it couldn't hurt.