Cory barbel erosion

This tank is approx 25 days old. One of my Cory panda lost all it's barbels, total erosion. This substrate is finely uniformed and very light for Corys barbels to be pushed around. Also, the substrate is clean and not ticker than 2cm. I can see the Malaysian Trumpet snails digging through the sand (literally since the sand is very light) at all times.
I am performing weekly 25% water change and cleaning the filter sponge. I have very good water flow + good surface agitation.
I can say for sure, the substrate didn't cause this erosion, and I am not sure what did.
I am feeding them with Krill flakes, Tetra Tabimin (for Corys) and Sera Vipachips (for Corys). Also with normal flakes (Vitakraft).
No ammonia nor nitrite. Remaining Corys seem to be doing well. One Cory panda dyed.
Total 4 Corydoras panda and 6 Corydoras melini.
Photo showing MTS digging through the substrate;

3 of the 6 small mystery fry are still living and growing. By the shape of their fins, I would say I have got some sort of Rainbow specie, not sure which yet (assumption). Time will tell.

Corydoras melini group

I introduced new Corydoras. This time the Corydoras melini, 6 of them. According to Planet Catfish, they grow to max 4.5cm, and this was one of the reasons I chose them for this Cory aquarium.
I am feeding them with Aquatic Nature Hi-quality Krill flakes, sinking wafers from Sera, and Hikari Protogen (infusoria sticks).
I believe these snails are having fun, don't you think? Snails are beneficial in my opinion, they do eat/clean all the food particles not found by fish, and by doing this, they are limiting any unnecessary accumulation of ammonia (rotting food). Also they are very good at cleaning plant leaves from algae and bacteria.

Corydoras panda 5

And so, 20 days after the set-up, a small group of 5 Panda Corys had find a new home (my 54 lit. aquarium). They seem not to be under any stress. As you can see on this video, they are shifting the sand for food and shoaling together.

Microorganisms and a few tiny fry

I have noticed lots of tiny dots on the glass, took some macro shots and here is what I got;
The first photo shows a flagellated protozoa Dinobryon (not harmful).
Second photo shows Ciliates called Stentor (not harmful).
EDIT; I have spotted a few tiny fry swimming in mid-water. I was very surprised. My assumption is that they hitchhiked with plants as eggs. They hatched a few days ago (6 fry). I am curious to see what fish this is :-) I will keep them until they grow bigger, and then, depending on which specie they are, decide will I continue keeping them in this set-up.

Setup Date - 7th March '08

This aquarium will house mostly Crydoras sp, and for that reason I have used finely uniformed 0,5mm sand. Rough gravel can damage Cory's barbels. I keep a few Cory trilineatus in a 180 liter planted aquarium with 1.2mm gravel, which caused the barbel erosion. Crydoras shift through the substrate all the time in search for food particles and therefor the sand MUST be of fine texture and preferably small 0,1 to 0,5mm (tiny rounded pebbles e.g. like Quartz).
The sand layer is no ticker than approx 2cm. Ticker layers of substrate can accumulate dirt over the time that, again, can cause barbel erosion, so good hygiene is very important.
I will use only plants that can be rooted on wood like Microsorum sp, Anubias sp. and Java Moss.
At the moment I have one bunch of Egeria densa and Hygro. polysperma to help me with the cycling process (they can uptake the NH4 very fast), until the beneficial bacteria develops (in a few weeks). I rinsed a filter sponge from one of my older tanks into this one to seed it with beneficial bacteria.
I also seeded Infusoria (sticks from Hikari Protogen).
A few Malaysian Trumpets and Red Ramshorn snails were introduced today.
I am thinking to keep Corydoras elegans, probably a group of 9 specimens.
This is a low light tank, with a 320 l/h power head with a filter sponge.