Ok, I'll do as suggested but shrimp have been dying over last 2 months, well before the rescape. One died in the holding tank(54l) whilst other tank was being redone. I started with 11 0r 12 and now have 5 crs left, one went for a walk, rest died in the tank. I had kept the external filter running too so thought with water changes and a mature filter that it would be ok, oh dear.