# Bio-Chem Stars



## otter (Oct 22, 2005)

A few weeks back I put Filstar Bio-Chem Stars into my XP2, The box directions say to use 20 for every 100g, so I put 10 in for my 46g. I looked at them when I cleaned my filter at WC and they're still the same size (I thought they'd expand) and looking lonely in the big 'ol filter compartment, should I add more? Also, I've seen it stated that half of them should be replaced every six months, but the directions say that they never need to be replaced. What do you think?


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## Betowess (Dec 9, 2004)

Is it a planted tank? I think most just use sponges and something like bioballs or in my case the ceramic rings for nitrifying bacteria colonies. Only thing I add to that is some crushed coral or oyster shells to keep my KH up - which is depleted by injecting CO2. I think the biochem stars will deplete your micro nutrients. That is the same reason that most of us don't put activated charcoal in a planted tank cannister filter. HTH bob


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## krazykidd86 (Jul 27, 2005)

> Biochem Stars are made of a porous polymer substrate and the inner pores and those at the surface provide excellent conditions for the development of the biological filter. Biochem Stars should be located in the biological compartment of your filter.


Bio-Chem stars are a type of bio media that has porous surfaces for bacteria to grow on. 
It will not expand, and it won't hurt to add more since more bacteria grows it. 

Best of Luck roud:

the KIDD


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## malkore (Nov 3, 2003)

the KIDD is right: bio chem stars look like sponges, but they aren't...just extremely porous material. they have more surface area than ceramic rings, so are superior in that respec. However I've heard they do have to be replaced annually, unlike ceramic rings.

add as much as you like...then you'll always have some extra stars to jump start future tanks.


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## otter (Oct 22, 2005)

> add as much as you like...then you'll always have some extra stars to jump start future tanks.


that's a great idea!

but do they deplete micros like carbon?


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## DarkCobra (Jun 22, 2004)

Dan Otterdahl said:


> but do they deplete micros like carbon?


That was an interesting enough question that I hit the books to find an answer. 

The chemical adsorbency of a material is determined in great part by its surface area. Both the Biochem Stars and activated carbon have large surface area, by virtue of their porosity.

The Biochem Stars have pores of 50-70 microns. The pore size of activated carbon depends on grade, but is typically no more than 10 microns, and can range down to mere thousandths of a micron.

Therefore, activated carbon has a lot more surface area. And while the Biostars will adsorb a small amount of trace elements, it will not be anywhere near as much as activated carbon. Probably too small an amount to notice.


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## otter (Oct 22, 2005)

Thank you DC!


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## CmLaracy (Jan 7, 2007)

Very good DC, I've been looking for that answer for days! Thanks.


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## crazy loaches (Sep 29, 2006)

This is an old thread, but since it resurfaced I'd add my $0.02 that I'd go with other bio media that is cheaper and just as good if not better than the stars. Heck I even setup one XP3 with just potscrubbers for bio. The other has Matrix.


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