My Shrimps Are Dying!

I am at a loss to understand what is causing my adult shrimps to die.

I have lost two blues(1 male and 1 female) in three days and mumma red is looking poorly.

Here's my vitals for the tank;

No siphoning done since babies born (3 weeks)
Weekly water changes of about 40%
Dechlorinator added to new water
Beta Glucans added at each water change
Feeding once a week on finely ground shrimp cuisine and offering occasional veggies

Ammonia and nitirte 0
Nitrate 50 ( this is surprisingly high but water change due tomorrow)
PH 7.4
KH 6 - 10
GH 21

Temp 24*C

MTS snails share tank.

Pond snails are being removed as I see them and fed to the assassins in the big tank.

The babies are all doing great! Red and blues all lively and growing well.

The adults that eventually die go very quiet and stop moving and sometimes they hide away and it's only when I look for them I find their bodies.

Things I can think of that might be responsible;

I got new plants for the big tank last weekend and I didn't rinse them before putting them in the tank (slapped wrist)
I have fiddled in the big tank and then gone straight to the shrimp tank without cleaning my hands in between. If the new plants have been treated in copper, could I have transferred this into the shrimp tank on my hands?

I was squashing the pond snails and leaving them in the tank to be eaten, could this be related in any way?

I have been growing algae on rocks on my kitchen window sill by keeping them submerged in tank water in a tub. I last put some lovely green rocks in the tank on monday, am I poisoning the shrimp? (incidentally, I give these rocks to the ottos in the big tank too and I found a dead otto last night as well).

I can't think of anything else that I'm doing or not doing that could effect the tank and it's inhabitants. I am wondering if I should actually give the tank a small clean as the gravel is disgusting now. I know I've been advised to "never clean my tank" by the shrimp forum but it doesn't sit right with me to let a tank get so dirty.

Anyone got any clues or suggestions?

FC76 

Hi Fishcake,
I'm sorry to hear about the problems you're having with your shrimp.
I'm sure someone else with more knowledge will be replying soon, but here are my thoughts for what they're worth:
1. I don't know whether your water is hard or soft, but mine is soft and I add a supplement to the water when I change it (it goes in the water before you add it to the tank) – it's called Bee Shrimp Mineral GH+. I know you aren't keeping Bee shrimp (I added 10 red and white ones a couple of days ago), but I use it with my red cherries and they seem to be fine with it. On the back, it says:
"Bee shrimp mineral contains all the important minerals and trace elements your shrimp need for well-being, an intensive colouration, successful breeding and healthy growth. It also furthers plant growth and the microbial regeneration of biological filter substrates."
2. A few times a week, I also add a pinch of Bacter AE (made by Glas Garten), which also adds microorganisms, amino acids and enzymes and improves the development of the biofilm in the tank. I think it's a kind of food source as well.
You could try asking Seb at pro shrimp whether these might help your shrimp and he might have some ideas as to what's causing your problems?
I hope you find out what's happening and that it's all resolved soon.
Diz 1

I don't know if this might help but when I was in p@h the other day someone was buying some plants and the assistant asked if they had snails in their tank. As the plants that were weighted down rather than planted in baskets had been dipped in a chemical that killed snails.

If it's not good for snails it might not be good for shrimps.

Anne