Replacing Gravel Bed for Corys

[David J. Braunegg]

I was at the LFS last night, thinking of getting a few more Corys as buddies
for the two I already have. (They are labeled as Corydoras punctatus, but I
believe they are actually C. leucomelas.) The LFS uses a relatively fine
gravel, maybe 1/8" diameter. I noticed that their Corys would burrow their
heads into the gravel looking for food. Given that they are bottom feeders,
I assume that this is normal, even desirable, behavior.

The gravel that the LFS sold me when I got my setup is much coarser,
1/4-3/8" diameter. Depth of gravel in the tank is 1.5". The best the Corys
can do is get anything laying on top of the gravel or between the top-level
gravel pieces. There is no way that they could burrow into this gravel. It
doesn't seem to me that this gravel supports the natural behavior of my
Corys and that the Corys cannot serve their role in eating old food if they
can't burrow into the gravel to get to it.

Should I consider changing my current gravel to fine gravel or to coarse
sand? (LFS sells coarse sand, but not the fine gravel they have in their
tanks. I would have to try a different store, or maybe Home Depot, to find
fine gravel.)

I run a Penguin mini-filter with bio-wheel, but I've been told that the
gravel provides a significant portion of my biological filtration. Is this
true? If so, it sounds like I could really screw up the tank by replacing
the gravel. Can I suspend the new gravel in an old stocking in the tank for
a few weeks to "inoculate" it? Is there some other way to get the right
bacteria growing on the new gravel before swapping it out for the old stuff?
Can I run a fishless cycle in a different tank with only water and gravel,
but no filter? (I don't have a second filter, but I'm pretty sure I can
borrow a tank.)

It also seems to me that the LFS told me to put a lot of gravel in the tank.
(The 1.5" in my 10-gallon tank was from three 5-lb bags of gravel, as I
recall.) Could/should I reduce the gravel to 1/2" or so in depth?

Will I run into problems vacuuming sand or fine gravel, i.e., sand/gravel
getting sucked up the tube?

Like I said, I am not sure that it is even a good idea to consider replacing
the gravel, so any input would be appreciated.

Thanks,
Dave

[JazzyB!]

Have you considered buying sand from your local building supplies store?
It's FAR cheaper than anything you'll purchase at the LFS. That's what I've
done for my corys and they seem to like it. At least that's what they said
last night.
"David J. Braunegg" > wrote in message
...
> I was at the LFS last night, thinking of getting a few more Corys as
buddies
> for the two I already have. (They are labeled as Corydoras punctatus, but
I
> believe they are actually C. leucomelas.) The LFS uses a relatively fine
> gravel, maybe 1/8" diameter. I noticed that their Corys would burrow
their
> heads into the gravel looking for food. Given that they are bottom
feeders,
> I assume that this is normal, even desirable, behavior.
>
> The gravel that the LFS sold me when I got my setup is much coarser,
> 1/4-3/8" diameter. Depth of gravel in the tank is 1.5". The best the
Corys
> can do is get anything laying on top of the gravel or between the
top-level
> gravel pieces. There is no way that they could burrow into this gravel.
It
> doesn't seem to me that this gravel supports the natural behavior of my
> Corys and that the Corys cannot serve their role in eating old food if
they
> can't burrow into the gravel to get to it.
>
> Should I consider changing my current gravel to fine gravel or to coarse
> sand? (LFS sells coarse sand, but not the fine gravel they have in their
> tanks. I would have to try a different store, or maybe Home Depot, to
find
> fine gravel.)
>
> I run a Penguin mini-filter with bio-wheel, but I've been told that the
> gravel provides a significant portion of my biological filtration. Is
this
> true? If so, it sounds like I could really screw up the tank by replacing
> the gravel. Can I suspend the new gravel in an old stocking in the tank
for
> a few weeks to "inoculate" it? Is there some other way to get the right
> bacteria growing on the new gravel before swapping it out for the old
stuff?
> Can I run a fishless cycle in a different tank with only water and gravel,
> but no filter? (I don't have a second filter, but I'm pretty sure I can
> borrow a tank.)
>
> It also seems to me that the LFS told me to put a lot of gravel in the
tank.
> (The 1.5" in my 10-gallon tank was from three 5-lb bags of gravel, as I
> recall.) Could/should I reduce the gravel to 1/2" or so in depth?
>
> Will I run into problems vacuuming sand or fine gravel, i.e., sand/gravel
> getting sucked up the tube?
>
> Like I said, I am not sure that it is even a good idea to consider
replacing
> the gravel, so any input would be appreciated.
>
> Thanks,
> Dave
>
>

[Brenda]

David, about a year ago I switched from gravel w/ undergravel filter,
to sand with Penguin filter w/ bio-wheel. The corys definitely like
the sand better. In terms of biological filtering, there is actually
more surface on sand, than gravel, so the sand provides just as much
filtering. And your bio-wheel will provide more than adequate
biologicals anyway. Here's what I did to switch over:

1. Move fish and cleanest of old tank water into buckets with air
stone. Extra buckets of the old tank water kept to the side are also
good.

2. Empty rest of tank. Clean and rinse thoroughly and dry.

3. Wash new sand/gravel with de-chlorinated tap water. Place in
bottom of tank.

4. Set up your ornamentals.

5. Place the extra buckets of old tank water into the tank. Add the
fish and the last of the tank water.

6. Add your treated fresh water just as though it was a water change.

I had no problems whatsoever with my fish. You will have to be
extremely vigilant about not over-feeding with the sand substrate as
the slightest over feeding WILL give you a cloudy tank or will soil
your filter a lot faster. However vacuuming the sand is actually a
LOT easier than gravel. You will mainly just skim over the top of the
sand. It's not like gravel where the excess food can fall through and
spoil at the bottom. Sand WILL get sucked up - but less than you
think. The odd time, the sand will clump in the vacuum, but all I do
is shake the vacuum tube and the sand usually either falls out or goes
into the collection bucket. Allow any vacuumed sand to settle in the
collection bucket. Pour off the dirty water. Rinse out the sand.
Add my fresh water and water treatment. Mix to dissolve and add back
into the tank. No problems at all.

If you simply want to change gravel, you can take some old gravel and
add it to the new stuff, but with keeping some of the tank water, I
feel you don't have to do that.

Anyway, my opinion? Switch to sand. Not only the corys but any
loaches, and any other bottom feeders will like the change. As well,
evidenced by how much the sand gets moved around, the other fish like
it too. Your next toughest choice will be colour. I have black -
mixed blessing. It shows every bit of excess food. But on the other
hand...you know when it's time to vacuum!

Brenda

"David J. Braunegg" > wrote in message >...
> I was at the LFS last night, thinking of getting a few more Corys as buddies
> for the two I already have. (They are labeled as Corydoras punctatus, but I
> believe they are actually C. leucomelas.) The LFS uses a relatively fine
> gravel, maybe 1/8" diameter. I noticed that their Corys would burrow their
> heads into the gravel looking for food. Given that they are bottom feeders,
> I assume that this is normal, even desirable, behavior.
>
> The gravel that the LFS sold me when I got my setup is much coarser,
> 1/4-3/8" diameter. Depth of gravel in the tank is 1.5". The best the Corys
> can do is get anything laying on top of the gravel or between the top-level
> gravel pieces. There is no way that they could burrow into this gravel. It
> doesn't seem to me that this gravel supports the natural behavior of my
> Corys and that the Corys cannot serve their role in eating old food if they
> can't burrow into the gravel to get to it.
>
> Should I consider changing my current gravel to fine gravel or to coarse
> sand? (LFS sells coarse sand, but not the fine gravel they have in their
> tanks. I would have to try a different store, or maybe Home Depot, to find
> fine gravel.)
>
> I run a Penguin mini-filter with bio-wheel, but I've been told that the
> gravel provides a significant portion of my biological filtration. Is this
> true? If so, it sounds like I could really screw up the tank by replacing
> the gravel. Can I suspend the new gravel in an old stocking in the tank for
> a few weeks to "inoculate" it? Is there some other way to get the right
> bacteria growing on the new gravel before swapping it out for the old stuff?
> Can I run a fishless cycle in a different tank with only water and gravel,
> but no filter? (I don't have a second filter, but I'm pretty sure I can
> borrow a tank.)
>
> It also seems to me that the LFS told me to put a lot of gravel in the tank.
> (The 1.5" in my 10-gallon tank was from three 5-lb bags of gravel, as I
> recall.) Could/should I reduce the gravel to 1/2" or so in depth?
>
> Will I run into problems vacuuming sand or fine gravel, i.e., sand/gravel
> getting sucked up the tube?
>
> Like I said, I am not sure that it is even a good idea to consider replacing
> the gravel, so any input would be appreciated.
>
> Thanks,
> Dave

[NetMax]

"David J. Braunegg" > wrote in message
...
> I was at the LFS last night, thinking of getting a few more Corys as
buddies
> for the two I already have. (They are labeled as Corydoras punctatus,
but I
> believe they are actually C. leucomelas.) The LFS uses a relatively
fine
> gravel, maybe 1/8" diameter. I noticed that their Corys would burrow
their
> heads into the gravel looking for food. Given that they are bottom
feeders,
> I assume that this is normal, even desirable, behavior.
>
> The gravel that the LFS sold me when I got my setup is much coarser,
> 1/4-3/8" diameter. Depth of gravel in the tank is 1.5". The best the
Corys
> can do is get anything laying on top of the gravel or between the
top-level
> gravel pieces. There is no way that they could burrow into this
gravel. It
> doesn't seem to me that this gravel supports the natural behavior of my
> Corys and that the Corys cannot serve their role in eating old food if
they
> can't burrow into the gravel to get to it.

I would not over-worry about it. Their natural habitats are probably
mud, do you want to emulate that ? ;~) Check their barbels. Corys
should long pointed barbels. Anything less and you could have bacteria
in your substrate which is damaging them. The gravel should be rounded
(sharp stones are quite hard on them). Corys will still serve their
purpose because food does not penetrate very deeply in sand anyways (it
rolls along the surface). I suspect Corys dig in aquarium sand because
they can. In nature, they would be exposing all sorts of tiny bugs which
churn through the mud feeding on anything decomposing in the anarobic
conditions.

Corys do have a lot of fun plowing through sand, but don't change
substrate just for that. There are pros & cons to sand which you should
familiarize yourself with. If sand was better than gravel, then everyone
would have sand (much cheaper). Underwater, fine sand turns into
something resembling concrete (until you press quite hard into it),
especially some of the cheap play sand from hardware stores. It can also
play havoc with magnetically driven impellers (which drive the majority
of our filter systems). It's also self-levelling, so if you like a
sloped look, you will be building leak-proof tiers. As sand goes, if you
decide to try it, I suggest you try the sand-blasting suppliers (they
have all sorts of grades), and don't use a lot (beware of anaerobic
conditions). If you are prepared for it, it can make a very nice look
for your tank (and the Corys won't complain).

> Should I consider changing my current gravel to fine gravel or to
coarse
> sand? (LFS sells coarse sand, but not the fine gravel they have in
their
> tanks. I would have to try a different store, or maybe Home Depot, to
find
> fine gravel.)
>
> I run a Penguin mini-filter with bio-wheel, but I've been told that the
> gravel provides a significant portion of my biological filtration. Is
this
> true? If so, it sounds like I could really screw up the tank by
replacing
> the gravel. Can I suspend the new gravel in an old stocking in the
tank for
> a few weeks to "inoculate" it? Is there some other way to get the
right
> bacteria growing on the new gravel before swapping it out for the old
stuff?
> Can I run a fishless cycle in a different tank with only water and
gravel,
> but no filter? (I don't have a second filter, but I'm pretty sure I
can
> borrow a tank.)

On bacteria, the good nitrifying bacteria (removes ammonia & nitrites)
are aerobic (need oxygen), so it's pretty safe to say that there isn't
any in sand (there is no oxygen replenishment to any of the sand grain's
below the surface contact to water. The anaerobic bacteria (I won't call
them the bad bacteria, as they are essential, but problematic in large
numbers) are responsible for decomposition. They don't cause too much of
a problem when surrounded by a gravel substrate which is vacuumed
periodically. They do cause a problem when they are given a spot to grow
and are left alone. Undisturbed, they create nasty toxic gases (which
kill fish easily). Many people who use sand as a substrate also keep MTS
in their tanks. The MTS (Malaysian Trumpet Snail) is a little cone shape
nocturnal (mostly) livebearing (I never checked) snail which churns sand,
continuously releasing little pockets of nasty gases (before they can
accumulate into larger toxic pockets).

To answer your question, borrowing some gravel will seed your aquarium.
Borrowing some sand wouldn't do much. Keep in mind, my understanding is
that the anaerobic bacteria you are seeding (from substrates) reproduces
much much quicker (more like normal bacteria) than the nitrifying
bacteria we associate with 'cycling' a tank. If you keep you filter wet
& running, you should not have any significant worries about cycling,
imo. Cycling a tank, is something we do to the first tank in a house.
Cycling a subsequent tank is about walking over to the new tank with an
aged filter, feeding the fish sparingly for a few days while checking
water parameters.

> It also seems to me that the LFS told me to put a lot of gravel in the
tank.
> (The 1.5" in my 10-gallon tank was from three 5-lb bags of gravel, as I
> recall.) Could/should I reduce the gravel to 1/2" or so in depth?

Less is better. Less gravel accumulates less detritus (making vacuuming
easier). Less sand provides less opportunity for anaerobic conditions.
Always use the least amount of substrate dictated by your requirements
(which might be plants, aquascaping slopes, arranging shelters etc).

> Will I run into problems vacuuming sand or fine gravel, i.e.,
sand/gravel
> getting sucked up the tube?

The detritus just wanders over the sand, so it's easy to vacuum up, but
more obvious until you do ;~)

> Like I said, I am not sure that it is even a good idea to consider
replacing
> the gravel, so any input would be appreciated.

You got it :o)
NetMax

> Thanks,
> Dave