Lava rock as biological filter?

  • #1
I'm wondering if lava rock can work as a biological filter as my 14g biocube I'm guessing has not enough biological filtration(cloudy water). will lava rock work?
  • #2
Lava rock is used more for course filtration ( physical particles) than biological.
While bacteria will grow on it, you would be better off looking at material with more surface area such as foam or sponges.
  • #3
Before we start on the lava rock, do you know your tank's parameters? Ammonia, Nitrite, Nitrates? These values will help determine if you're low in bio-filtration. If you have any ammonia or nitrite, then either a) The tank is still cycling or b) There is insufficient bio-media/surfaces for the bacteria to cope with the bio-load. Without testing, it's kinda difficult to help guide you on this one.

That said, generally speaking, beneficial bacteria will grow on any surface. The more porous the surface, the greater the population of bacteria can grow, so in theory, yes the lava rock will add to your bio media. Can someone remind if lava rock is inert ???

If I remember rightly though, you'd need to add a powerhead or something to 'force' water too flow over the lava rock, for it to be of any benefit.
  • #4
Lava rock is chemically inert.
  • #5
ty Dino (I was pretty sure it was)
  • Thread Starter
  • #6
well because of my parents in debt they said I can't have a test kit because it cost a lot for a good one(+$20)
  • #7
Frequent, small water changes will help as well. Say, 10% every other day.
  • #8
Hmm, ok.
Would your LFS test a sample for you?

Whilst cloudy water is typically a bacteria bloom, it could be cloudy from particles in the water etc.

Whilst the lava rock may help, I don't believe it will fix the issue. I would try reducing the bio-load on the tank, or more regular water changes to keep things in check.

by Dino
  • #9
Bwhahahah, how do you think thought the ninja's in the first place?
  • #10
Just to clarify, the cloudy water is white. Or is is green? Looking straight down into to tank is the best way for me to determine this in my tanks.
  • Thread Starter
  • #11
its a whitish green

changed the water...eberything is clearing up, I hope it stays like this
  • #12
Walmart sells this reddish-colored lava rock in the Garden Center.

It's all porous and rough and whatnot, lots of surface area, and I'm thinking it's cheaper by volume than a lot of biomedia like bioballs and biomax.

Do y'all think it could be a viable filler for AquaClears, sumps, canisters, etc.?
Matt B
  • #13
My dad used to use that and coconut husks for biomedia back in the day. I know its viable as a biomedia I'm just not sure how to tell if its safe or how its stacks up against "bio max" ceramic types.
  • #14
Lava rock is fine. It could raise your ph depending on how much you use.:thumbup:
  • #15
The biggest issue with using it as bio media is it will become clogged with gunk from the tank, and needs to be cleaned. Other than that it works fine. Eheim use to sell it as part of their filter media. I'm not sure if they still do or not.
  • #16
Hmm, yeah, I guess a prefilter would mostly solve the gunk issue though.
  • #17
well it should not change water properties much it has been fine addition to many tanks I have 2 pieces I use as anchors for 2 anubias in my 10 gallon I'm planning on using more of it to cover some objects I am going to use as caves.
  • #18
My in-laws use it in their DIY pond filter. Seems to work great.
  • #19
This is great news, folks, thanks! I love finding cheaper alternatives to expensive aquarium supplies. I guess I need to pick up some lava rock next time I visit Wallyworld...
  • #20
I took mine to a hammer, placed in mesh bag, and added to canister filter. Never had any problems or issues.
  • #21
I would wash them really really well though. washing them also helps you find the ones that float... I have read there is a very minimal impact on aquarium chemistry with the use of lava rock but they have high aluminum content and high iron most commonly.
  • #22
Hmm. What would aluminum and iron mean for the aquatic environment?
  • #23
not a lot of people have reported issues with using lava rock as bio media or even decor but red lava rock being high iron could leech iron into the water. Specifically iron oxide as when red lava rock is formed it is rapidly cooling lava exposed to steam the steam oxidizes the iron in the lava as well as other minerals as it cools resulting in the red pigment.

the term for lava rock is basalt also I found that if the ph is below 8.2 there is less chance at leeching than above that.

It should be mostly safe. Also it does not grow algae very well both pieces I have in my tank look the same as when I put them in... over 3 months ago.
  • #24
I have done the same as psalm, took a hammer to it and used mesh for the cannister, I've also converted a sw skilter filter for my 29 freshwater tank, as all kinds of room and loaded it up with lava rocks, I also have lava rock in 3 of my tanks. I got all my lava rock from my yard, its everywhere around here. No problems works great!
  • #25
Ok, great.
  • #26
I have multiple large pieces of lava rock in my tank as decorations. I've tested the iron and it wasn't high at all. For all the parameters that I can test for (pH, ammonia, nitrite, nitrate, phosphate, iron) it didn't make anything out of whack. My parents did use it in aquariums a long time ago though, so it's possible that anything that would going to leach out already did.
  • #27
I am just putting out a warning that if he puts it in and suddenly have a mass die off or something happen in the tank it is likely there will be no issues as most of the iron and minerals should be encapsulated in volcanic glass but WASH IT REALLY WELL.
  • #28
Hmmm. Again.

I think I want to try this, especially as a lot of people have done it with no problems. However, I appreciate Lunas's caution... I tend toward paranoia rather than recklessness.

Right now, I've got a couple of small pails of soil soaking for a dirted tank. I'm thinking that once I'm done with those, I'll be able to use the pails to soak the lava rock... and for similar reasons. The dirt gets soaked so that it doesn't poison the livestock, and the lava rock gets soaked so that it doesn't leach excess minerals into my tank water.

It can't hurt and might be a real lifesaver. Plus, if I add a nice big airstone at the bottom of the gravel layer to circulate the water, I can add ammonia and get some bacteria pre-established on the lava -- another plus!
  • #29
For what it's worth many people don't soak dirt, myself included, and have no problems
  • #30
I tend toward paranoia

LOL. I blame my mother. Doesn't everyone? ;D I don't mind a little extra prep time; I have a lot going on and might as well soak the dirt/lava rock while I'm waiting to have a chance to set it up anyway.
  • #31
A lot of people do soak their dirt, so definitely nothing wrong with it if you have the time and space. Soaking probably would have saved me a few water changes trying to get the floating particulate out
  • #32
See? It's not really paranoia if your dirt really IS out to get you!
  • #33
I tend to agree with the above.

Lava rock is relatively inert and shouldn't mess with your chemistry. Many have used lava rock over the years, and many still swear by it. The only 'caveat' I would add, make sure it's in a high flow area -> kind of redundant if you're going to crush and put in the filter, but if you were to just toss a lump of it in your tank without flow, it would not be as efficient.

FWIW - Base Rock, Live Rock, Aragonite rock are all not really suited to most typical tropical freshwater systems as they will raise pH and hardness.

Regarding the aluminium and iron: Not sure on the iron aspect, I'm sure it could leach a little into the tank, but if you plant the tank, that's a bonus. I have not read many stories of lava rock causing iron issues though.

Aluminium: I'm fairly certain that unless your pH drops to around 5.3, the aluminium will remain harmless. Seachem actually use aluminium oxide in their Phosguard product: <- there's a section about aluminium in the page.
  • #34
Thanks! I'd say that if my pH drops to 5-point-anything, I'll have bigger issues than trace aluminum. Good to know that it's harmless at high pH, though.
  • #35
From what I read lava rock needs to have 8.2 ph or higher to cause it to dissolve lower should be fine and unless it is going into salt water or a cichlid tank the ph should not rise to 8+ if it does that is a problem

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