Cherry Shrinp Don't Like Gravel

i have the ar-650t tank that holds 30 gallons and because of its ridiculous heigh, it is on the front room floor because being only 5 feet 2 my arms aren't very long.
in the tank i started with 12 red cherry shrimp, 2 amano shrimp, 2 octo catfish and 12 assassin snails to help get rid of the very many baby pond snails. i now have probably somewhere between 50 to 100 cherry shrimp from an eighth of an inch to adult size.
the tank has quite a bit of plant, elodea and masses of guppy grass (which if dyed the right colour would be great for making pubic wigs, thanks borat for that one) and a lot of rocks with holes for hiding places. i have had, as far as i know, not had the assassins breed, unless they perhaps were unknowingly crushed by me or thrown away on the many lettuce leaves.
anyway i started with 3 inches of gravel in the bottom and because the tank had so much plant and rock, i hardly seen many shrimp or snails, but then i put a layer of play sand on top and blinking heck out they all came, brilliant. when i put a couple of very large 10 inch lollies (bought a pack of 50) in the tank they are completely swamped with shrimp within 2 minutes, and that is great fun because one of the amano's is a large female that is always full of berry and she goes up and down the lollies bullying and knocking off the cherries, great to watch.
so i would recommend that if you have a gravel substrate and don't see your shrimp very much, put at least an inch of fine sand over the gravel.
ivor
 

Nice looking tanks Ivor!

Hello, made some shrimp lollies today, and this is what i used.

first of all the hardware. an electric hand blender and a mortar and pestle, tin foil, and gas oven.
a bag of spinach, rocket, and cress from aldi, dried in the oven, blended and powdered in the m&p, a handful of plain flower, dried mixed herbs, a couple of bay leaves, a generous helping of powdered fry food, bakers yeast, half a dozen dried, blended and powdered oak leaves, (massive oak tree right beside my home) dried thyme and dried ginger.
i wasn't sure if they would like all of that (last time only used half of those ingredients) but they loved them and swarmed all over them. all eventually crushed into powder. not forgetting the beaten egg (white and yoke) that i use as the glue and yes unlike most youtube vids i use the yoke as well. i then lay out a sheet of tin foil and place a dozen 10-inch wood skewers and coat them with the egg, i then sprinkle the powdered mix all over them and place the whole thing in the oven and bake at gas mark 5 for 10 minutes.
thinking about it, i should have made a youtube vid of the whole process, i might do that next time.
everybody with shrimp should try making lollies and you only need to start with a couple of ingredients. 
I also buy ready-made lollies from ebay, 50 for about £15, that are green and are probably made from spirulina, and they also love them. if i could afford it, i would definitely add spirulina to the mix.
have a great night guys.
PS. i wish that i could make the mixture sink, maybe soak in a small drop of tank water to saturate it first. beside the few other fish in the tank, i have well over 200 shrimp and so i feed them a massive amount every day their favouite being tropical and catfish pellets from pets at home and made by love fish.