Consensus on Lava Rock?

[vince-1961]

Over in the SPS coral section, someone suggested that lava rock should not be used as filter media in a wet/dry sump. He said the lava rock dumps heavy metals into the water. First I had heard of that.
This thread is being established to get the general consensus on lava rock as the filter medium in a wet/dry filtration system. Please post your two cents' worth.

 

[keith burn]

Originally Posted by vince-1961
http:///forum/post/2752782
Over in the SPS coral section, someone suggested that lava rock should not be used as filter media in a wet/dry sump. He said the lava rock dumps heavy metals into the water. First I had heard of that.
This thread is being established to get the general consensus on lava rock as the filter medium in a wet/dry filtration system. Please post your two cents' worth.
Imo no you do not know what is in it, and if you do how do you clean it?
But not a good filter.

 

[mr_x]

i voted bad. all i ever heard was that it would not work in a reef system. i have never had experience with it though....just what those before me have stated.

 

[spanko]

I have always been afraid of the heavy metals that may be contained in it so have stayed away. There are too many other alternatives to take the chance on Lava Rock.
JMO

 

[reefkprz]

this is a quote from a koi pond gardening site, even in freshwater the metals are a concern. not to mention the other points reducing the usefullness of lava rock.
Begin quote
"lava rock are colored clinkers a silicate slag waste product from iron ore smelting, steel making blast furnaces, or silicate type slag from coal fired electrical generating plants. ( the by product of burning Coal) The clinkers, while being porous, will clog unless you have a very good pre filter system. They do not allow water to flow through them, which wastes valuable filter space. All the little nooks and crannies in the faux Lava Rock eventually become clogged with algae, mulm, sand etc. making the effectiveness the same as throwing pieces of solid stone into your bio filter. There is also some concern that these clinkers contain heavy metals harmful to your aquatic environment. With most homemade bio filters there is a certain redundancy built in (bigger is better) so it will take some time depending on your stocking levels and filter system, for the lava rock bio filter to lose it's effectiveness.
Lava rock is inexpensive to replace but, over the long run it is a maintenance nightmare. The sheer weight, abrasiveness and time spent cleaning, should be enough to steer you away from this product. We've cleaned many a lava rock filter and I can tell you, that trying to clean this media with anything less than a steam power washer, is an exercise in futility and will not get it back to it's original surface area. " end quote
here is a chemical analysis of a lava rock
well there is no exact gaurantee of what lava rock may or may not contain but here is the results of one sample of lava rock run through a rigorous testing regime. (in other words your lava rock may contain more or less or none or additional to the following)
Lava rock
Mineral Content
Nitrate Nitrogen.................................4.0 p.p.m.
Phosphorus........................................ 6.0 p.p.m.
Potassium......................................... 59.0 p.p.m.
Zinc.............................................. ...........6 p.p.m.
Iron.............................................. ....10.0+ p.p.m.
Copper............................................ ...5.5+ p.p.m.
Magnesium.......................................2. 0+ p.p.m.
Boron............................................. ....10.0 p.p.m.
Sulfate........................................... ......7.0 p.p.m.
Organic Material.......................................... .5%
PH................................................ .........8.2 Units
Calcium..................................1.3 Meq/100 gm*
Manganese...........................0.6 Meq/100 gm*
Sodium...................................0.1 Meq/100 gm*
Cation Exchange Capacity..3.2 Meq/100 gm*
* Milli-Equivalent per 100 grams

 

[valeram]

Nice info. I have some lava rock that came from my old FWA and I was thinking of putting it in my SWA. I was dead sure to put it in until I've done my research about it. Do you think it will be safe to use it since it was in my FWA for more than years?

 

[reefkprz]

bump this one up so the OP can get more feedback.

 

[aztec reef]

I wouldn't use lava rock in Saltwater..first, its a silicate-based rock, oppossed to calcium carbonate-based.
second, the dark color= excess condensed minerals/elements and metals, some of which can be toxic to marine organisms and/or promote numerous algea/diatom blooms..
Third, is not porous..
Fourth, it contains no life..

 

[aztec reef]

Originally Posted by valeram
http:///forum/post/2753366
Nice info. I have some lava rock that came from my old FWA and I was thinking of putting it in my SWA. I was dead sure to put it in until I've done my research about it. Do you think it will be safe to use it since it was in my FWA for more than years?
NO.
Cause FWA don't compare to Saltwater requirements. Plus medications, additives,distorted water chemistry, are within the lava rock..which can slowly leach out into aquarium not to mention the already silicate-based rock's composition...

 

[vince-1961]

well. Seems lava rock is taking a pounding!
I don't want to use bio-balls. So what's another good medium? Crushed oyster shell? Want something that will support both aerobic AND anaerobic bacteria.

 

[jaymz]

Originally Posted by vince-1961
http:///forum/post/2754361
well. Seems lava rock is taking a pounding!
I don't want to use bio-balls. So what's another good medium? Crushed oyster shell? Want something that will support both aerobic AND anaerobic bacteria.
Live rock rubble. If you have a LFS that sells base rock for cheaper than live rock you could get a good sized piece and break it up or try to buy some rubble.

 

[reefkprz]

Originally Posted by vince-1961
http:///forum/post/2754361
well. Seems lava rock is taking a pounding!
I don't want to use bio-balls. So what's another good medium? Crushed oyster shell? Want something that will support both aerobic AND anaerobic bacteria.
if your going for aerobic and anoxic you'll want at least fist sized (or larger)pieces of LR you can fill in between with smaller rubble rock, in the wet dry section I would only focus on aerobic bacteria and utilize a couple very large chunks of rock fully submerged elswhere in the sump for anoxic. in a trickle zone it's going to be nearly impossible to create an anoxic zone(low oxygen) and impossible to create anaerobic zone (no oxygen) (which you dont really want in your tank anyhow) anaerobic bacteria in a reef system is a bad thing, basicly it would be all hell breaking loose in a closed system. the chance of oxygen debt and poisoning of your tank would be very high.

 

[gmann1139]

Wow. I think this is the most one sided poll I've ever seen.

 

[cranberry]

Originally Posted by reefkprZ
http:///forum/post/2753162
this is a quote from a koi pond gardening site, even in freshwater the metals are a concern. not to mention the other points reducing the usefullness of lava rock.
Begin quote
"lava rock are colored clinkers a silicate slag waste product from iron ore smelting, steel making blast furnaces, or silicate type slag from coal fired electrical generating plants. ( the by product of burning Coal) The clinkers, while being porous, will clog unless you have a very good pre filter system. They do not allow water to flow through them, which wastes valuable filter space. All the little nooks and crannies in the faux Lava Rock eventually become clogged with algae, mulm, sand etc. making the effectiveness the same as throwing pieces of solid stone into your bio filter. There is also some concern that these clinkers contain heavy metals harmful to your aquatic environment. With most homemade bio filters there is a certain redundancy built in (bigger is better) so it will take some time depending on your stocking levels and filter system, for the lava rock bio filter to lose it's effectiveness.
Lava rock is inexpensive to replace but, over the long run it is a maintenance nightmare. The sheer weight, abrasiveness and time spent cleaning, should be enough to steer you away from this product. We've cleaned many a lava rock filter and I can tell you, that trying to clean this media with anything less than a steam power washer, is an exercise in futility and will not get it back to it's original surface area. " end quote
here is a chemical analysis of a lava rock
well there is no exact gaurantee of what lava rock may or may not contain but here is the results of one sample of lava rock run through a rigorous testing regime. (in other words your lava rock may contain more or less or none or additional to the following)
Lava rock
Mineral Content
Nitrate Nitrogen.................................4.0 p.p.m.
Phosphorus........................................ 6.0 p.p.m.
Potassium......................................... 59.0 p.p.m.
Zinc.............................................. ...........6 p.p.m.
Iron.............................................. ....10.0+ p.p.m.
Copper............................................ ...5.5+ p.p.m.
Magnesium.......................................2. 0+ p.p.m.
Boron............................................. ....10.0 p.p.m.
Sulfate........................................... ......7.0 p.p.m.
Organic Material.......................................... .5%
PH................................................ .........8.2 Units
Calcium..................................1.3 Meq/100 gm*
Manganese...........................0.6 Meq/100 gm*
Sodium...................................0.1 Meq/100 gm*
Cation Exchange Capacity..3.2 Meq/100 gm*
* Milli-Equivalent per 100 grams
I wouldn't even think we'd need a poll after that info. Case closed fo rme.

 

[vince-1961]

The reason I wanted a zone of anaerobic bacteria is that I thought they ate nitrates. I have some cheato in my refugium, but it's just a small piece at present and not able to eat that many nitrates. With a 225 gallon tank (and salt costing $50 for 150 gallons' worth of salt), doing frequent water changes as the primary means of nitrate control is not my first choice of options.
Would much rather just include something in the closed system that uses nitrates as food. Any ideas?

 

[reefkprz]

anoxic zones consume nitrates {low oxygen} (thats the goal of a DSB) to create a low oxygen zone for denitrification. an anerobic zone [No oxygen] will also do this but is VERY dangerous in a closed system. one mishap and its hiroshima and nagasaki on a DT scale.

 

[trouble93]

This maybe off the mark, but thought oxygen rich mix was a good thing in a swa?

 

[vince-1961]

Reefer dude,
My sand bed is currently a bit uneven but averages 2 to 3 inches, some parts deeper, some shallower. Do I need to make it deeper to get my denitrification?
Can I use beach sand? When the tide goes out, my local beach has hard, flat sand which is great for riding bicycles on! It's got VERY small grains. I put some of it into my 20 gallon QT tonight as an experiment to see if it would result in a diatome bloom (i.e.- silicates).
Would this be a good source of "live sand", like if I waded way on out and got some sand that was always submerged ... or maybe just got some of the "mid-tide" sand which is sometimes exposed to air and sometimes under water, or should I go for the sand that is always dry, even at high tide??? The QT experiment is sand that is always dry, even at high tide. (Well, excluding rain, hurricanes, spilled beer and so forth
What if I went well offshore and just scooped sand up off the bottom? (Out there, the sand has larger grains and the water is clear and greenish colored, not the s _ _ t brown it is here inshore where we have a hundred miles of saltwater marshes and barrier islands.)

 

[reefkprz]

off shore sand would be better. the stuff you find directly on the beach and in tidal zones tends to have a lot of secondary pollution (motor oil, gasoline etc) due to the wave action washing it in.
as for dept. a bit deeper would be more effective at providing anoxic denitrification. 4-5 inches would be better 2-3 inch sand beds are actually considered the trouble depths that are hardest to maintain because they are too deep to be fully aerobic, and too shallow to have a proper anoxic zone. I would shoot for 5 inches

 

[reefkprz]

Originally Posted by trouble93
http:///forum/post/2757815
This maybe off the mark, but thought oxygen rich mix was a good thing in a swa?
high oxygen IS good in your water. in your sand bed you want the first inch or inch and a half to be aerobic (oxygenated) and as you progress deeper into your sand bed (provided you have a DSB) you want oxygen levels to drop so it can support anoxic zones for low oxygen bacteria to consume nitrates.