The Huey Hungs over that side of the pond seem almost identical to the Hydro line here;
http
/www.aquariumguys.com/hydrosponge1.html
I run the Hydos if I get them cheap at an auction or swap, I generally make my own, which ends up cheaper. Three of the Hydro IV's provide bio filtration for a 150 gallon tub, one is fine for anything 40 gallons or less.
The PW filters look to be a glorified box filter, I run these as well with larger fry on up to adults;
http
/www.jehmco.com/html/box_filters.html
I run the LJRBF's, one per sponge filter on larger tanks or tubs. I have found that fry can sneak into the box filters when they are small, and will get hung in the floss, I run sponges only until the fry are large enough to be unable to squeeze through the slots in the top of the box filters.
Sponge filters in a fry tank are more for bio filtration than mechanical filtration. You can get quite a bit of mechanical filtration from a sponge filter, this calls for increased water flow, which increases turbulence, young fry generally do not do well with turbulence.
I've had the Hydros running for years, with no need at all to change the sponge. They are run as low flow bio filtration, I crank the floss filled box filters a little more for mechanical filtration, and replace the floss as needed, this depends mainly on the stocking. Bulk floss is dirt cheap, it is nothing more than poly fill used for pillows & such.