Granite media-testing for compatibility

[Blue Hiller]

Does anyone know an easy way to determine if my granite gravel is ok to use in media beds? I seem to recall a simple "put it water with xxx" and watch the reaction (if any). Thanks.

[Blue Hiller]

Doh. Just found it. Place granite in VINEGAR and see if it fizzes (bad). Also leave in water for several days and wach Ph.

[Greg McCord]

Hi Blue. I was curious, did you do the test and what were the results? Are you thinking of using the smaller "drainage stone" from your local stone yard? Greg

[Blue Hiller]

Yes, I am going to use 1/2-3/4 granite gravel. In Maine we have a lot and it is cheap. Did the vinegar reactive test (no fizz-good) and also have a simple in my water to watch Ph.

[Rob Nash]

We use 3/4" granite on the bottom 6" and 1/2" granite on the top 6". Works great! When the system goes acidic, add 3/4" river rock (not pea gravel.. Too small) up to 30 % by volume.. Be sure it is stired into the top six inches or so... It needs to make contact with the water. We haven't adjusted pH in as long as I can remember.

[Blue Hiller]

What is, if any, the specific reason the system "goes acidic"?


Rob Nash said:

"When the system goes acidic, add 3/4" river rock (not pea gravel.. Too small) up to 30 % by volume..

[Blue Hiller]

Noticed there are micro bubbles coming off granite in test water. Is that normal off gassing?

[Keith Rowan]

the nitrification process causes the system to "go acidic"

[Blue Hiller]

Ok, so what, if any, effect does the river rock have on the acidity? Thanks.

[Blue Hiller]

Very informative. Thanks!