Morning Ady and congrats on the tank. Exactly the one I have for the shrimp.
1st - the lid. They cost around £15. I know because grandson #2 sat on his and had to replace it.
If you do replace it with glass, remember to get extra clips as they break pretty easily. (Even though the glass was broken when you bought it they should still have supplied you with the clips that held it in place ?)
I removed the carbon from mine and replaced it with an extra ceramic cartridge.
In front of these cartridges you will find a row of slots for the water intake.
I'm sure they are big enough for shrimp , especially baby shrimp, to get sucked into so I have pushed a piece of sponge between the wall of that and the first cartridge. It's a tight squeeze but doesn't affect the flow. There is also a slot really low down, which when you fill the tank you will see water pouring out of it. I tried to seal that off to stop babies getting in but it was too small for my fat arthritic fingers. !
I also have a piece of sponge, the same diameter as the cartridge fitted between the two ceramic ones. Again a tight fit but it goes in.
In the compartment next to the Filter/heater compartment there is a largish lump of black foam. It doesn't completely fit the space so, on the advice of Aquaone I have filled that with ceramic rings and extra sponge and some fine filter floss. It gives you extra seeded supply for if you need to set up a quick quarantine tank.
I have a strip of black sponge along the edge where the cartridges/sponges, filter etc go. I did that to stop my original tiny Endlers being able to jump the gap. I've left that too to try and stop the shrimp climbing into the filter dept
Now, all of these extras were put in place originally because I kept fish in the tank.
You may not need to go to those extremes for shrimp as their bioload is much smaller than fish.
I kept it all in as it was already there.
My water is crystal clear. In fact, so clear that it puts my larger second hand one with its Fluval 4 to shame. There are always bits floating in that tank, despite having added extra foam and filter floss to it.
I also made a mesh lid cover to keep the shrimp and snail in as there is quite a gap around the sides due to the way the glass fits to the tank.
I made (well my husband did) a perspex cover from greenhouse perspex as we thought that would work. Despite fitting all the edges with L" shape strips to strengthen it and help keep it in place (it just slipped over the top of the tank) , it still bowed to some extend, probably due to the heat from the lights and heater.
I was going to just get a piece of glass slightly oversize to fit on the top.
Hope that all helps. The water level does have to be quite high due to the position of the slots.
The filter is VERY powerful for this size tank. I have another piece of the black sponge attached to a home made spray bar.
You will have some trouble getting the correct spray bar fitment and if you do manage to locate one I would really appreciate the tip as to where you got it please. Mine is Not pretty but is effective.