Need Help picking rocks/gravel for my grow bed(pics)

[nickt444]

I got my grow bed filled half with Hydroton.  I need another media that isn't as expensive.  I have plenty of rock options at my local market but I am not sure which one is best, and safest to use.  I created an album of the pics I took today.  If anyone can help me make this decision it'd be a huge help, and greatly appreciated. 

I posted all the images here http://imgur.com/a/fGhXK#0 .

Feedback needed.. Thanks...Oh grow bed is 6ft long 2 feet wide 1 foot high.

[George]

http://aquaponicscommunity.com/forum/categories/media-topics/listFo...

You'll find information here

[TCLynx]

Do a Fiz test

Fiz test blog post

[Timothy P. Kelly]

TC,

Point of confusion. I did a vinegar test on pea gravel sample and it bubbled a little, similar to the expanded shale in the video. Is this material, in fact, acceptable? I got the stuff for free and was told it is of river origin, but I assume it would be an issue in regard to pH. I have granite available at a local supplier, but it's bigger than I would like.

[TCLynx]

That pea gravel you tested.  You might rinse it off and test it again.  Sometimes a bit of dust or even air pockets in rocks will cause a few bubbles and I wouldn't be terribly worried about that.  However, if you get fizzing or if the vinegar gets cloudy it tiny bubbles, you don't want to use it.

How big is the granite?  1-2 inches would be a bit big but 3/4" would be great though granite is heavy.

[Timothy P. Kelly]

TC,

The size I saw ranges from about 1" (of course it's irregular) on down. I can get it from a local garden center for $5.00/5 gallon bucket.

I'll try that test you suggested. Stay tuned.

TCLynx said:

That pea gravel you tested.  You might rinse it off and test it again.  Sometimes a bit of dust or even air pockets in rocks will cause a few bubbles and I wouldn't be terribly worried about that.  However, if you get fizzing or if the vinegar gets cloudy it tiny bubbles, you don't want to use it.

How big is the granite?  1-2 inches would be a bit big but 3/4" would be great though granite is heavy.

[TCLynx]

$5 for a 5 gallon bucket isn't a great price though I suppose it's better than the bagged rock that is probably around $4 for 2/3 of a 5 gallon bucket.

Now my thinking is different since I usually get my gravel by the ton or cubic yard instead of in small quantities.