Backyard Aquaponics
A place to discuss aquaponics

Is this material suitable for filter material?

In what form?

In addition to the what sort of polystyrene, what sort of filter? Static or moving bed? Do some research of using HDPE/LDPE beads.

I would agree with Bunson, much better option physically tougher and stable.

And cheaper too...

There is the ethical dilemma, beads are killing the earth and the oceans. How do we dispose of them "properly" when we're finished with them?

I'm personally against using polystyrene in AP, the stuff does degrade and break down in the sun, no doubt leaching some toxic chemicals into an essentially closed system. Fine particles of PS must end up in the fish, as well as the chemical breakdown products of decomposition, as it breaks down in UV light, so IMHO, it is best avoided.
As Bunson mentioned earlier HDPE beads may be a better option, HDPE is certainly a lot tougher and more chemically stable, especially in UV light exposed areas.

Thanks for the input. has anybody used HPDE pellets in moving bed filters? Seems like it would be comparable to K1, just not as good BSA. I can compensate by having a larger amount. Does it still clean with air like the K1? Trying to get prices on virgin material, and not having much luck yet.

The Kaldnes design has been copied (and some might say, improved) and there are a number of manufacturers in the US, and, their products happen to be considerably cheaper than the original.

Just to save you reading through a long paper on nitrification and filtration.
"
Floating bead filters
The floating bead filters are expandable granular filters that display a bioclarification behavior
similar to sand filters (Malone and Beecher, 2000). They function as a physical filtration device or clarifier by
removing solids (Chen et al. 1993), while simultaneously providing a large surface area for the attachment of
nitrifying bacteria, which remove dissolved nitrogenous wastes from the water (Malone et al. 1993). Bead filters are often referred to as Bioclarifiers for their ability to perform both Biofiltration and clarification in a single unit.
Clarification is the process of removing suspended solids from the water. Suspended solids in
aquaculture are generally small particles (< 100 micron) of undigested or partially digested food, bacteria, algae,
clay, and silt, suspended in the water column. Bead filters remove the suspended solids by at least four different
mechanisms as water is passed through the packed bed of plastic beads. Particles > 100 microns are subjected to
physical straining. For slightly smaller particles (50 to 100 microns) the most dominant mechanism is settling.
Suspended particles (5 to 50 microns) are removed by interception, a subtle process caused by collisions between the particle and the bead media surface. Finer particles (< 20 microns) are removed through bioabsorption, the capture of particles by the bacterial biofilm.
Floating bead filters are resistant to biofouling and generally require little water for backwash. The
bead filter is typically either bubble-washed or propeller-washed during its backwashing procedure, which expands the bed and separates trapped solids from the beads. The beads used are food-grade polyethylene with a diameter of 3–5 mm and a specific gravity of 0.91, and a moderate specific surface area of 1150–1475 m2/m3 (Malone et al.
1993). Bead filters advantages include their modular and compact design, ease of installation, and operation. In
addition, they can be used as a hybrid filter for both solids removal and nitrification"

Sleepe- much appreciated!
Where would one purchase polyethylene of that spec?

Your best bet is to go to a plastics moulding firm and buy from them (be really nice), you want the virgin HDPE or LDPE non coloured beads. I had thought the size was 4-6mm but it doesn't really matter, I also thought the SG was slightly higher.

Emphasise the words "virgin" (so they don't give you recycled beads, which could contain almost anything) and "food safe"; a food packaging manufacturer would be my first contact.

I happen to have a customer that makes packaging machines for the food industry and they have different bags of plastic at their plant. hopefully, some are the right type. Thanks again.

Coach,
Did you ever find the beads you were looking for?

Yes, I hope they work. they are going in my MBBF, which is a converted sand filter with back wash function. I plan on also having an additional "T" to be able to add extra air to be sure that if I need to clean the media, I can have my 1 HP regen blower push some extra air into it. I'll also need to add some stainless screens dies to the small sizes of the media. It will be my last filter after RFF and shade cloth and before degassing and sump. Hopefully, it will give a large volume of bacteria to keep things running smoothly.