My New Shrimp Cube.

Just read through the whole thread, nic little tank set up . Found it pretty interesting to see all the changes being made over time.
 
I like the idea of the mesh and the moss growing so you can create a sort of carpet , how is that panning out?
Hard to tell from your recent pictures.
 
And yes, Galaxy rasboras and Celestial Pearl danios are the same specie of fish, Galaxy being the old name I believe. And most folk I think use Celestial Pearl Danios and a lot of LFS, in UK anyway call them Celstials. But I'll be honest, i dont think a 20 litre cube is big enough for these little guys, despite being s small specie, they are pretty active and the males can be aggressive towards other males in small confines, I personally keep CPD's in a 3 foot tank and honestly.
 
Black Crystal are truly beautiful and being SS grade, thats going to be real nice but probably more expensive and harder to care for.
The higher the grade of shrimps, the more specific conditions they need to be in really.
Crystal Shrimps in general can be quite difficult to look after as they require soft acidic water, pH up to 6.8 max, gH 4 - 6 and kH 1-2. Very specific waters.
 
Poor water quaility is often the cause of the demise of many crystal shrimps. So it is important that these shrimps are in these specific tank set up, crystal are pretty delicate. Just as long as you're aware and have done your research as well as prepared for that, then you're good to go.
 
I am a fan of HOB filters as they are easily accessible and the the filters are pretty adaptable for most types of media. So am a little unsure why you say the HOB is useless, you do not mention why you don't like it.
 
Though generally speaking, dedicated shrimp keepers tend to use sponge filters as these are much less unlikely to suck up shrimplets. So either of these are pretty good to use for this type of set up
 
The native Zebra shrimps that Baccus mentions, they do look pretty good but I cant really comment on those due to lack of knowledge on them. Hopefully you can find reliable inforamtion on these

 

The Aqua One Clear view is a terrible type of HOB, I had one and hated it with a PASSION from the first attempt at setting it up. I now have all just the standard Aquaone type and have never had an issue with them. Aqua World type HOB comes a close second.
The only internal filter I would ever really trust with shrimp is the old corner wool/ fibre air driven ones that years ago was all you could get