Using scoria

[beachy]

Can any one tell me the does and donts of using scoria as biological filter media? will it affect my water chemistry?

Just thinking that i might put some in my sump

[Warren]

Yes, scoria works well. Make sure you get the bigger stuff, not the small type used on driveways etc. It need to be 10mm or bigger so it doesn't clog up and block the flow through the sump.

You'll need to wash it well. It's best to acid wash it with Hydrochloric (available from pool chemical suppliers). Use rubber gloves and lots of caution, as it's pretty dangerous stuff. You can buy HCl 1L. Put the scoria in a 20L bucket. Pour the HCl over it and top up with enough water to just cover it. Leave it for a couple of days. Tip a small amount of the HCl into another bucket and dilute 20:1 at least. Pour down the drain. Repeat until all the HCl is gone. HCl is not good from drains and need to be diluted very well when dumping it. Rinse the scoria well 3-4 times. After you're finished, put the hose down the drain and run for 30 minutes to flush.

Add one bottle of budget bleach to the bucket of scoria and top up with water. Leave for another 2 days. Tip down the drain and rinse very well.

Pour the scoria out onto the path and leave to dry completely for a week. This will expell any remaining chlorine.

Rinse again 4-5 times to remove any last traces of acid or chlorine.

Get a glass of tapwater and check the PH. Add a handful of scoria to the water and leave overnight. Check the PH again for no change. If it's ok then the scoria is ready. If not, keep rinsing and repeat the PH test.

Scoria is created by volcanic eruptions. During it's creation it can have all sorts of heavy metals and other toxic material combined into it's structure. The HCl wash is to help remove most of what will leach out.

After the scoria is created it may get organic matter trapped in it's pores. The chlorine soak (and the HCl soak) will break down and dissolve most of the organics.

It's still a good idea to keep a close watch on the fish after adding the scoria to make sure the are no toxic chemicals leaching out. I've used scoria many time in the past with no negative effects. It a very good cheap high surface area media.

[beachy]

Thanks Warren, thats great, bit of a mission though.It would still be worth doing as i have heaps of room in my sump so why not use it for something good

[FishBait]

Hey Jason

I have used scoria in a filtration setup for native freshwater. It has worked well and has been running for close to a year. I have had no problems with using it. I like the scoria because it has a huge amount of surface area. In my sump at home in my fish room I have used open cell foam in a bin designed as a wet and dry system. It is 3 layers of foam. This is easier to maintain and clean. I just remove one piece of foam and hose it off them put it back and off it goes again.

[beachy]

cool thanks fishbait, not wanting to sound lazy, but could i just rinse the scoria and boil it for a while? i know that warrens way is prob the best, and i would prob run more of a risk with my fish.

[Warren]

I suppose you could try a bit without treating it. See if it works while keeping an eye on the fish... Would certainly save a lot of hastle.

The only reason I went to so much trouble is the filter was on 39 tanks with around 1000 fish. Didn't want anything going wrong. I know lots of people, Fishbait included, who have no trouble using it straight. Just test it first by adding only a little bit.

[beachy]

Cool thanks warren, i wouldnt want to risk 1000 fish either.

[FishBait]

Hey Jason

Yes I admit that I didn't go through the full proceedure for cleaning the scoria, all I did was to wash it to clean out the dust and fine stuff then filled the filter (I used a large ehime canister filter) and left it running for a couple of days, gave another flush, then put on to tank and started cycling.

good luck

Kerry

NZKA 248