Re: Onyx, gravel or sand

["James Purchase" <jppurchase at rogers_com>]

Terry asked:
"I am going to spring for some onyx substrate by Seachem.  Any experience
and
any preference?  Sand or Gravel?

I am favoring gravel so I don't suck the sand out with the power filter or
python during cleaning.

I have a lame planted tank now and am making improvements....new lights new
substrate.  Will still be a lower light no CO2 tank."

I have a tank which contains Onyx sand, and both I and the plants love it.
You might want to buy a bag of the gravel to sprinkle in some areas of the
substrate but the sand works perfectly. DON'T worry about it being too
fine - it doesn't compact (at least I haven't had it compact on me).

When you are rinsing it, be careful - some of it is very fine and you don't
want to let it run down the drain. I used a fine mesh kitchen seive
(stainless steel) to rinse it and still lost a fair amount of the "fines".

It sounds like you are a beginner with fully planted tanks - the reference
to gravel cleaning gives you away. There are many practices common in "fish
tank" maintenance that are both unnecessary and counter productive in a
fully planted and properly maintained plant tank, and extensive gravel
vacuuming is one of them. The only thing you might want to do is keep the
larger bits of mulm picked up - there is NO NEED AT ALL to get all of the
decayed mulm out of the substrate - it provides needed nutrients for the
plants once it has decayed. I never vacuume my substrate - I merely use a
powerhead to gently "blow" the settled detritus up into the water column
where it gets picked up by a mechanical filter. Occassionally, you can run
your fingers or a stick gently thru the top layer of the substrate to ensure
that it has not become packed, but there is no need to get overly agressive
unless it becomes totally rootbound (which can happen over time with large
stands of Crypts).

James Purchase
Toronto