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White pumice stone vs clay pebbles

Discussion about fish health and water chemistry.

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Post Wed Feb 22, 2017 6:33 am
Moretroutbell Level 4 Member
Level 4 Member

Posts: 103
Anyone know where white pumice stone is available locally? I purchased 4 liters of Seachem Matrix online and am wondering where to find a cheaper buy in bulk source. (I think Matrix is just pumice stone ???) Local garden places have told me pumice is not really available in midwest. While at a local garden center I did buy a bag of those clay pebbles used for aquaponics thinking they would also be a good way to get a lot of beneficial bacteria for biological filtration.(Clay pebbles are light and porous) Has anyone used those clay growing pebbles as biological filtration media before? After rinsing I don't think they would cloud water but will they break down over time?
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Post Fri Feb 24, 2017 12:34 am
Passionfish Level 20 Member
Level 20 Member

Posts: 12302
Location: apple valley, mn
Seachem answered this question.
http://www.seachem.com/support/forums/f ... -vs-pumice

Seachem's premise is matrix is pumice that has been tested for low reactivity to anything found in tropical fresh water or salt water tanks. Any other pumice used would be unknown regarding safety.
Testing of seachem matrix has shown that in some systems, anerobic bacteria capable of denitrofication colonize inside of matrix. Theoretically, this would allow for longer intervals between water changes.

Based on following definition, it is unlikely any pumice is reactive.
Pumice is composed of highly microvesicular glass pyroclastic with very thin, translucent bubble walls of extrusive igneous rock. It is commonly, but not exclusively of silicic or felsic to intermediate in composition (e.g., rhyolitic, dacitic, andesite, pantellerite, phonolite, trachyte), but basaltic and other compositions are known. Pumice has an average porosity of 90%, and initially floats on water.
Like a complete unknown

Post Sun Feb 26, 2017 11:27 am
Moretroutbell Level 4 Member
Level 4 Member

Posts: 103
Thanks for the reply. I loaded a bunch of air box filters with several liters of Matrix and opted to not use the clay pebbles for time being. I would think the clay pebbles would still be safe as they are used for hydroponics and growing but wonder if they would break apart over time if fully submersed.
Speakin Tanganykian on the weekend has me freakin

Post Sun Feb 26, 2017 6:45 pm
Passionfish Level 20 Member
Level 20 Member

Posts: 12302
Location: apple valley, mn
It is my understanding that expanded clay pebbles contain pores created by heating clay pebbles at high temperatures resulting in clay expansion or pourous ball.
This seems like a natural for bio filtration. However, the proof is in the pudding. Until somone actually tests expanded clay pebbles as a bio filter, I would not rely upon them as bio filter.

Pumice is a different matter. Matrix is pumice and it has been proven to function as a bio filter once cycled.
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