Hi, my name is Linda and I live in the South of Scotland. We recently moved here and built a new pond to house our fish. When we were moving I found quite a few babies and did not want to put them into the big pond until it was more established and they had somewhere to hide. At present I have put the 4 sprats into a small aquarium, 18 litres with a filter pump. I am finding the nitrate is building up very quickly about every 2 days although I have also tried adding nitrate minus. Can anyone give me some advice, I have been feeding them sparingly and their size varies from 1 inch to around 2 1/2.