# LECA as biological filter media



## tzen (Dec 31, 2008)

I'm going to be using LECA for my bio filtration media, and wondered if anybody else has tried it for this. 
I'm using the Hydroton brand of LECA (Lightweight Expanded Clay Aggregate). Here is some promo info: 
The clay is formed into pellets and fired in rotary kilns at 1200ºC. This causes the clay to expand, like popcorn, and become porous. Hydroton hydroponic growing media is light in weight, does not compact and is completely reusable - it can be cleaned and sterilized after use. They are also inert, pH neutral and do not contain any nutrients. 
This versatile medium has hundreds of tiny pores that retain moisture. Large 8 to 16 mm average diameter size allows for maximum oxygen to the roots while providing a stable base for plant roots grown in active hydroponic systems or passive hydroculture applications.
Perfect for passive, wick, and subirrigation use, individual hydroculture pots or hydroponic systems.​ 
The big benefit is the cost. 10 liters of it is about $10. 
I think the biggest reason it is not used more for bio filtration is because, for the small volume that most filters hold, $10 will also get you enough cute cylindrical pellets or sintered glass to fill the filter. 
Unfortunately for me, my DIY filter design has a fairly large volume, so I needed more, thus my reason for using a cheaper product.


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## trackhazard (Aug 24, 2006)

You could use hydroton I suppose. I've rinsed it a bunch though, and I've always gotten little brown particles coming off of it from the brow clay coating on the surface so it might be tough getting it super clean.

In a planted tank, plants = biofilter however. I usually end up filling my canisters with sponges for mech fitration and an occasional bag of purigen for tannins.

-Charlie


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