Alternative biological filter media

Elijahyar

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Hi guys I'm new here and new to reefing! This is my 1st post so be easy with me!! Just wondering if anyone has had success with the expanded clay aggregate commonly used I the hydroponic trade as a biological filter media? It seems to have a lot of the same qualities as something lije marine pure etc. But substantially more affordable. Anyone??
 

N.Sreefer

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The clay will break down add organic matter, phosphates, and tannins lowering the ph of the tank. Even in hydro set ups it breaks down over time (it does take awhile) with the turn over it would get in a sump and it being in saltwater I imagine it would break down quickly. I've used everything from pot scrubbies to perlite as biological media and imo chunks of live rock/ crushed coral causes the least issues. The problem with brightwell biocubes and the sort is they crumble and basically turn to dust after awhile.
 

legionofdoon

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It's really expensive, I have a koi pond with an attached aquaponics system and I went straight lava rock and pea gravel because of the price. The good thing about lava rock and pea gravel is that it's non contributing to pH changes. With aquaponics you don't want your water to be high in alk so you can't use limestone, I'm not sure about the clay but if it's used in hydroponics then I suppose it would lower pH like someone else said.
 

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legionofdoon

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It's really expensive, I have a koi pond with an attached aquaponics system and I went straight lava rock and pea gravel because of the price. The good thing about lava rock and pea gravel is that it's non contributing to pH changes. With aquaponics you don't want your water to be high in alk so you can't use limestone, I'm not sure about the clay but if it's used in hydroponics then I suppose it would lower pH like someone else said.
That's 4 feet deep by 8/8.
 

WheatToast

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You do not ever use those is a reef aquarium.
I used lava rock once in a marine system... it was moderately frustrating.
Yes, it was great at attracting life, but it, along with the rest of my freshwater rock and sand, contributed to an endless diatom phase.
Edit: or maybe the other rocks were responsible, or solely the lava rock, or the sand. I really don't know.
 

outhouse

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And yes lava rock has been used in reef aquarium in the past.
Stop your nonsense. Some types of rock, including many types of Lava Rock, contain minerals that are not good in aquariums. Even if the rock is non-toxic, it also needs to be porous. Most Lava Rocks are porous, but some are glass lava and not porous, so they won't work to reduce nitrates in aquariums.

Its a bone head move to use such, when plenty on live or dead proper rock can be found
 

legionofdoon

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Well they are silica based. Which in a marine tank has no benefits nor would I recommend using it but obviously it has been done. Marine and aquaponics are very different systems I thought I was being clear when I said that you can't use buffering limestone (calcium carbonate) but oh well.
 

outhouse

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My micro brittle stars, coralline, and bristle worms loved it, though :). I am still probably not going to use it again.
I did an octagon FO tank with Lava rock 30 years ago. It never worked out, and it was hard to keep fish alive in it. I understand your frustration. I played with for a year and out it went.
 

N.Sreefer

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The clay will break down add organic matter, phosphates, and tannins lowering the ph of the tank. Even in hydro set ups it breaks down over time (it does take awhile) with the turn over it would get in a sump and it being in saltwater I imagine it would break down quickly. I've used everything from pot scrubbies to perlite as biological media and imo chunks of live rock/ crushed coral causes the least issues. The problem with brightwell biocubes and the sort is they crumble and basically turn to dust after awhile.
I forgot the ph of the clay after being fired in a kiln is actually not that bad at 7. Still after seeing the sediment/sludge that builds in hydro tables with the clay over time, I would never use it in a reef.
 

legionofdoon

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Stop your nonsense. Some types of rock, including many types of Lava Rock, contain minerals that are not good in aquariums. Even if the rock is non-toxic, it also needs to be porous. Most Lava Rocks are porous, but some are glass lava and not porous, so they won't work to reduce nitrates in aquariums.

Its a bone head move to use such, when plenty on live or dead proper rock can be found
I'm not saying to use lava rock or pea gravel in a marine tank! I'm saying that it's been done before. Most lava rock is silica based (glass) and it most certainly does have a use in aquariums of the fresh water variety.
 

WheatToast

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Well they are silica based. Which in a marine tank has no benefits nor would I recommend using it but obviously it has been done.
Maybe it would be nice for a sponge tank then, but I agree that it usually does not belong in a marine system.
I did an octagon FO tank with Lava rock 30 years ago. It never worked out, and it was hard to keep fish alive in it. I understand your frustration. I played with for a year and out it went.
Same here. Now my system is devoid of freshwater rock and sand.
 

legionofdoon

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I forgot the ph of the clay after being fired in a kiln is actually not that bad at 7. Still after seeing the sediment/sludge that builds in hydro tables with the clay over time, I would never use it in a reef.
My bed is pre filtered so not much sludge, but my main filter is just gross and I'm not even using clay. Oddly it works better for me when I don't back flush it.
 
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