Backyard Aquaponics
A place to discuss aquaponics

does scoria really have a larger surface area then the clay?

yes

But it's not as nice to work with as far as digging holes to plant seedlings etc.

But then again its not that bad. I just see people push a seedling into their clay ball beds as it they were sticking it into a bowl of cream or something. I have to dig a little hole and place my seedling in then backfill. Not really a problem, and I went with scoria because of the extra surface area and it was a bit cheaper.

If I had plenty of money and lots of grow bed space, I'd go with the balls.

My system is only a small blue barrel half and half for GB and fish tank, and I have some NFT tubes as well, so I wanted to maximise my filtration. There is a thread on here somewhere, where someone had made some software to test grow beds. The software had a factor you set for your media. If you can find the thread, you can see in the software )spreadsheet I think) the ratios between the different media.

Having said that, the software and the "scientific" study that goes along with it sites no references, but if you look at a clay ball and some scoria, you can see there is a lot greater surface area.

There is some texture to the clay balls, but there is more texture on the scoria, and scoria also has an irregular shape. A sphere is the least surface area you can have for a given volume.

i'm using it in my biofilters seems to do the job!

I live on maui and i shovel my own red cinder right off the mountain. I got a lot of more red powdery kind too and it works great, so some is less surface area. I do have all kinds of different sizes. At first i thought the more powdery small ones would drain too my pond but it does not.

how serious do you clean the scoria..?

I have spent a few hours washing the scoria I got and have only managed to partially fill the 1st grow-bed..
Its driving me nut's and I need to 3/4 fill 2 850lt tubs and then a 500lt 1/2 IBC..

Juergen

fill the grow beds, then put a hose on the "return to FT pipe" and rinse it dumping the water. It will run clear after a few minutes and that should be all you need to do.

Even if you do nothing and dont rinse it at all, the system will show clear water after a bout 2 days.

I did nothng once, and put a sock on the pipe that put water to the grow bed. It collected a lot of fine red powder, and I think made it run clear sooner, but I suspect t doesnt make a lot of difference. In nature whenever it floods, rivers get silted, and fish and plants seem to do just fine.

2 tonne took me 2 days to clean in a cement mixer with the hose running in it i ran each load through the mixer for around 4 hours after that time there was still a fair amount of sediment in the water in the mixer but after filling the grow beds and letting water run through i have crystal clear water and scoria with no sharp edges

I took everyone else's advice and did not clean the scoria much. I hosed it quickly in sections as i removed it from the trailer, but didnt clean it otherwise. I just let the dust cycle through system to get stuck in GBs. I shoved some fish tank filter wool between my standpipes and media guard just to pick up some dust and assist in the process of slowing it down. After two days the water was no longer red. After about a week it was crystal clear.

Unless you are worried that the scoria dust might clog or ruin something in you system, I would not waste your time cleaning it thoroughly.

i got my red lava rock from Lowes, and the company who makes it is called QuikRete.
i spoke to a couple people who work the lava rock side of things for quikrete. both said its a "100 percent natural product. it is pulled from the ground and bagged up". I decided to use it after that.

Mine was more like 4 weeks.... but it did eventually clear up

our system has been running for a week now and hasn't cleared one bit. hopefully it does by the time it has cycled.

Mine took a week or so to clear up

Hi from flipper new member

Years ago I was called to a job at a major airport to backfill a long trench with a bobcat, the contractors had just finished replacing a 150 mm stainless steel fuel line, it was a very substantial pipe line that ran a long distance from the fuel tanks to an engine maintained test cell, naturally curiosity got the better of me and I asked why it had been replaced, I was told it had to be replaced because the design engineers insisted it was laid using a red scoria packing which in time ate holes through the line.
Ever since then I have avoided it like the plague.
True story Flipper.

I would guess the movement of the pipe wore holes in the pipe not because of chemical reactions or anything. Any conduit/pipe should be buried with no rocks against the pipe.

+ 1

That stuff is sharp and some of it is as hard as glass.