anaerobic gravel?

[andruboz]

so where does this become a problem? how deep does it has to get? if you stir it up while syphon-ing is that enuff? what about gravel under decorations? is there any test for toxins other than amonia and nitrites? is it worse with under gravel filters or external?

my concern is that i recently added finer sand gravel ontop of coarse to make may puffer more comfortable. now i wonder if i shouldnt yank some of the coarse out. [ in the 55 gallon . had 50 lbs of whitish aq. gravel and added another 15 of sand. ]

[NJ Devils Fan]

How thick is it?

[wetmanNY]

In fifty words or less, Mr. President: All our substrates are anoxic. No problem, generally.

[andruboz]

depth of gravel varys from say 2" to 3"1/2

[NJ Devils Fan]

Get a couple of fish that turn up the substrate, like cories. Also, you might want to look into a powerhead for extra circulation to furthur help prevent anerobic spots.

HTH

[Bantam]

unless your water flow is very slow you should be ok.

its not as much of a problem with gravel as it is with sand because there is some room for water to circulate between the stones.