# Perlite as Bio Media in Trickle Filter?



## auratum (Jul 6, 2006)

Folks,

Has anyone used perlite as a bio media in a trickle filter type application? I have seen lots of different things used, but never perlite. It seems like it should work - lots of surface area, light weight, porous, and relatively cheap... The stuff floats so you need to plan for that in the system design.

Thoughts?

Thanks!
Patrick


----------



## under_control (Jan 9, 2008)

I know that it is crushed easily and will break down in constant water after some time.


----------



## auratum (Jul 6, 2006)

Perlite is a mineral rock expanded by extreme heat. It doesn't disolve in water. It does crush easily, but I don't know that is breaks down by just being exposed to water... And if it does break down over time - I can just replace it, right? I guess I don't see any harm there as long as it doesn't plug off.

Has anyone used this before as a bio-media?


----------



## iceblue (Apr 27, 2004)

I've never heard of it being used as a bio-media but I don't see why it wouldn't work. It's basically a glass and just about anything that provides a surface for bacteria to grow on is suitable. I think where it might run into a problem is after it absorbs enough water to stay sunk. It might compact together not allowing for good air circulation which defeats the purpose of a wet/dry filter. Just a guess on my part.

If you do use it I recommend washing it thoroughly and wear a dust mask when handling it. I built a concrete background using perlite to lighten the mix and it has a lot of very fine dust. You really don't want to be breathing that stuff.


----------



## fishwolfe (Mar 27, 2005)

> You really don't want to be breathing that stuff.


neither do your fish :thumb:


----------



## goldoccie21 (Jun 15, 2008)

its used in hydroponics. I don't think its porus it's supposed to keep water on its surface. thats why the roots can get adequate o2. sorry about my spelling. but as long as the trickle is slow enough it should not be a problem.


----------



## Mcdaphnia (Dec 16, 2003)

I suppose getting glass fragments in your lungs or gills sounds bad. However it sounds fairly safe according to one manufacturer:
http://www.idahominerals.com/Perlite%20 ... 20MSDS.htm
This stuff is used as a soil additive and if you ever get an aquarium or pond plant with some of this in its soil, it floats better than cork and will make a nice mess. Cichlids or koi will eat it, but it is indigestible and will return.


----------



## KaiserSousay (Nov 2, 2008)

Got to put a PLEASE don`t use it, out to ya...we have potted plants all around our pool, I am constanly netting this stuff off of the surface. This is just from the wind, can not imagine what runnig water through this stuff would do. :-?


----------



## auratum (Jul 6, 2006)

KaiserSousay said:


> Got to put a PLEASE don`t use it, out to ya...we have potted plants all around our pool, I am constanly netting this stuff off of the surface. This is just from the wind, can not imagine what runnig water through this stuff would do. :-?


This would be in a loosely packed bed with the water trickling down through it and a fine screen at the bottom to try to catch all the fine particles. I don't expect to have much wind in my basement nor do I expect it to dry out which is what allows the stuff to be blown about. We had green houses for years and used it mixed with the peat. It would tend to float on top when you watered heavily (pooling of water). I don't intend to run it liquid full.

I guess I will just have to try it as I haven't heard anything to scare me off yet. The only thing I had heard about its use for plants was burning due to flouride content, but I read an article that was written after a scientific study that proved that issue false.

Thanks for the input folks.

Patrick


----------



## prov356 (Sep 20, 2006)

Two possible issues that I can see. If it's too fine, it can easily get clogged with detritus and/or an 
organic biofilm that naturally occurs. You'll probably need a very fine prefilter media to try to avoid this. 
That's one of the problems of using smaller media in a wet/dry trickle system. Loosely packed initially, 
but it may not stay that way. I run a trickle filter with a drip tray that has a number of small holes. They 
clog with a brown organic film in time. I usually have to use pressure from a hose to open them up 
every few weeks or so. Picture the brown organic stuff that ends up in a protein skimmer. It's not 
something that many prefilter pads remove. I'd run a micron filter pad as prefilters in a setup like you're 
suggesting, and keep an eye on things.

Also, that fine screen you mentioned also runs the risk of clogging very quickly and you could soon find 
the media under water.

I think it's going to be a high maintenance media unless you can find some very coarse perlite. Even 
so, I'd make a way to easily remove and clean that fine screen.


----------

