Backyard Aquaponics
A place to discuss aquaponics

Silica in small amounts is good for you. Too much calcium is bad for you too. I think that at this point it is well established that scoria is quite safe. Despite that third arm growing out of my back.

scoria is a rock, i dont know of any rock that is not chemically safe to chew/suck on.

Cobalt stones would be a bad idea. They tend to be accompanied by cyanide.

We have a Scoria pit on our land. It changes light to dark depending on the clay base before it burned. When dropped in vinegar it will fizz like crazy until it has released all the air then stop. It can be soft or hard depending again on where it's mined. We have road base quality or dust(findings).... It breaks down if it's a not a good spot, other stuff will handle the excavator driving back and forth without any breakdown. I doubt it's dyed unless they want to uniform the delivery but honestly it's probably just dust collected. It will stain any white clothing pink and settles in a system nicely. Nothing toxic or all the livestock would be gone by now I'm sure. After it leaves the pits who knows. It's highly sought after since it's a non sparking base so if you drop a wrench at a gas leak it won't spark....

Hi just a tip for those of you liking the many benefits of scoria...but unhappy with the way it peels the skin from people and plants alike.

I threw a 5 gallon bucket in my concrete mixer and it was all nice and rounded off after only 1 hour. It did make about 1 quart of red dust in the bottom..but you have to wash the stuff anyway.

I contacted the local cement company, and he said he could indeed tumble 9 yards for me in one of his cement trucks at the standard hourly rate for a truck and driver. The only hitch is he will only do it on a day when it is too rainy for pouring cement so that the cement hopper can be used to fill the truck as it will be clean and empty on such a day.

I don't even notice the roughness anymore...

I used red lava rock for 3 reasons: 1.Its light, 2.Its great for breading bacteria, 3.Cost($50 a yard). The only problem was washing the rocks because that red dust quickly turns into a thick mud. All said and done, I am very happy with lava rock(scoria).

I have a heap of red scoria down the side of my house that was used as a top layer over the soil where there is a retaining wall.

Over the years there has been occasional use of pesticides to kill weeds. We are planning on pulling it all up (as we need to fix the retaining wall and hate walking on the stuff), but was wondering if it would be safe to used in an aquaponics system. Obviously well washed..

Any thoughts?

I think you mean herbicides

Sorry but I have to dump this one back on you. I don't think anyone here that can tell you the answer to that question. You could have it tested by a lab and you could try growing some different plants in it as a test, you could also ask the companies that made the herbicide how long it persists in the environment but it's largely up to you and how comfortable you are with using this - you know better than anyone else whether it will be safe because you have a better idea what was sprayed, how much was sprayed, how often it was sprayed and how recently it was sprayed .

Yes, you're right. Spot the non-frequent gardener lol!

Mostly I used roundup, but last year I did use something that is meant be residual in the soil for 12 months. 12 months has passed however..

I will give it a test run and see how it goes - would be a shame to discount it as we are getting rid of it anyway and would save quite a bit of money. It won't save money if it ends up killing a bunch of plants and fish though!

as noted in other threads around here some of it in the landscape market is artificially coloured.
raw scoria is fine.

+1 to the herbicides and weed killer residue. If you spray for termites or ants there may be pesticide residue.

Drainage scoria is what is wanted, not decorative.
however both can look reddish, so if you didnt buy it then its hard to know what it is.

scoria can be pretty porous, so a rinse probably wouldnt be enough as a good wash, if you washed it well and nothing was sprayed for a year, i would set up a small test system with some plants first, then something cheap but sensitive like trout fingerlings as a test.

Is there a way to tell the difference? Is it just the size that's different? I didn't buy it, it was put in by the previous owners over 10 years ago.

not sure exactly how you might test it, but the tend to dye / coat the decorative stuff.

I'd assume the dyed stuff would be quite uniform in colour, but the natural rock has a lot of variation in colour between individual pebbles.