Filter Media, Plastic, Ceramic, Matrix and other

I think the Prof has already answered this......like he said in a previous post......we now starting to go round in circles....

 

Hi @Dirk

I'm in the geotechnical industry :bigsmile:.

Firstly there are many types of sandstone. This is a sedimentary rock where the material is formed by grains of sand (varying materials dependant on the area) being bonded together by various minerals. The sandstone you describe is probably made of quartz sand grains (very hard), not rock, that is bonded together with potentially silica (but could be other minerals - which have varying bond strengths,wethering resistance and chemical properties). This is why I say that it could be a problem because when the boulders are crushed the bonding matrix is exposed and this is where the weathering would occur. As to the chemical reactions that occur within the matrix when exposed to water I will leave that in your hands as my chemistry is limited :blink1:. Sandtone can be highly porous and permeable but again is dependant on how it was formed and from what material.

So in summary, yes this is potentially a good biological filtration medium but it depends on which sandstone.

My advice would be that if you were buying this at a garden center look in the bottom of the bag. If you see a lot of sand it might give you your first indication of the type of sandstone and suitability. Also look at the individual "chips". Do they appear very granular and are the granules packed tightly together? Rub them together - do they crumble or are they solid. HTH

 

HI

Here is a pickture of some rocks i got from the plant next to my office, if i rub them nothing happens....



will this do the job?

 

Hi @oupoot - I'm at work so unfortunately I cannot see your pics as they are blocked by IT. I will take a look this evening.

 

Thanks for your input, going around in circles is what does on a forum, thanks anyway.

 

@MarcHawke send me your email address....

 

@oupoot - Ok, It's a bit difficult to tell from the pics :unsure:. Certainly looks like sandstone. I suggest you take a sample home, wash it properly :bath:, rub the rocks/chips/stones together and see what happens. Do they brake up? Do the acid test . Do they fizzle or disolve? Maybe leave some in water (if you have a test kit check the water before and after) and see what happens after a period of time. I would've suggested the geotechnical "taste test" but it wouldn't help you and you'd have gravel in your mouth :laugh:

 

@MarcHawke Tell me how the rocks should taste but i will was them off this weekend and rub them up, and also best way to do the acid test? vinegar should do the trick?

 

Pool acid or Vinegar. I'm currently looking at stone chips on my desk, that look a lot like the ones you and the prof posted, that my boss brought back from a site in Paarl. I will take a few shots in a bit...

 

Also these stones that i got from the plant some i can see is a sandstone that i can crush with my hands whilst other are just like normal stones, but i picked up about 30kg of the stuff so i will have to wash and iceleysort it ne

 

Sounding like you're sorted so just because I said I would.The 3 last and 2nd last pic are the same stone, just showing 2 different sides and how it's soft on 1 side and hard on the other. The final pic is after lightly rubbing the 2 stones in pic 1 against each other.........

 

just another question, how should my stoned taste?

 

@oupoot - Don't worry about the taste test. It's not a specific taste but more a feeling. We use the test to get a feel for grain size etc. Unless you really want to taste your rocks in which case go for it. It will taste earthy :laugh:

 

This is now getting rediculous, hahahaha !

 

I am having visions of other members going out and tasting their filter media :rofl:

 

Sounds intresting... maybe even like a cooking thread but anycase i would like to see profs opinions on all of this lol, and tasting im sure would be awfull for us non rock people, just another question, theses stones should be safe if the come off of mining ground?

 

Please don't taste your stones!
Someone may smack you on the back of the head, and you may loose a few teeth!
Rather do the vinegar test, by putting some drops on the stone and see if it fizzes...


Ps: This is on the lighter side-don't be offended...

 

What are they mining? The stones could be contaminated.

 

lol Stones can be used in quite a few contexts....

 

I think this thread needs to be wrapped up.

Marc thanks for clarifying the sandstone hardness issue. You make an important point that hardness of stones needs to be checked. My stones coming from the stream have been ground together to the point that only the hard ones are left, because I never have any sand coming out of my trickle filter that contains them.

Sanstone in principle is resistant against weathering and if you do the acid test on stone it should be negative or else that stone is not suitable.

I think that tasting stone should be left to the experts, but I will prefer to taste my glass of wine..... but try not to get stoned in the process.

Have a nice weekend guys, I hope, here in the Western Cape with a little less rain!!!!!

Kind regards,

Dirk