Onyx sand

["Roxanne Bittman" <rbittman at dfg_ca.gov>]

Walter wrote:  I was wondering if any of you folks that use Onyx Sand
could give an update? How long have you had it in your tank(s), and how
has the KH and GH reacted over this time? Thanks.


I have had 2 tanks running with Onyx sand about 2 years.  The GH and KH
have been steady, but at a high level even with R/O water, which has no
salts in it.  GH is at about 10-12 and KH is about 6.  These levels seem
fine to me.  I inject compressed CO2 to bring the pH to about 7.0 or
just below and the animals and plants seem fine.

However,  since I started using Onyx (since I redid these two tanks), I
have had a terrible problem with hair algae (Spirogyra) in both tanks. 
After 2 years of battle, I have apparently gotten the upper hand in one
tank thru water changes and lowered fertilizing.  I recently purchased
more SAEs and a few flagfish and maybe they are helping, not sure.
The smaller tank is still plagued with jt though.  I don't know if I
can blame Onyx but I never had this species of algae before and it is a
bear.  Anyone else noticed this problem?

Roxanne Bittman
Davis, CA