Where does filter go?

[carmelsundae]

We bought a 19ltr tank for our son, set it up on Thursday and added 5 wee barbs yesterday. The water was clear and some we added the fish it's gone all cloudy and dirty looking. We've the filter in the water and the nozzle where the water comes back out under the water. Today someone said the nozzle should be above the water . Which is right? And are our wee fish ok??

The nozzle should be just breaking the surface and causing lots of surface movement - that's what oxygenates the water.

It can take 4-6 weeks for a tank to mature properly, google "the nitrogen cycle" and "fish-in cycling".

A 19 litre is a very very small tank in fish tank standards and the smaller the tank, the more difficult it is to maintain good water quality. The cloud is normal for a new tank, it's a bacterial bloom, BUT at this early stage will also indicate an ammonia spike, which will be followed by a nitrite spike. Both these things are a natural part of the cycle but also toxic to fish - they scorch the gill tissue.

Look up guides for fish-in cycling, you'll need to do partial water changes several times a week. Ideally for Barbs you'd be better off with 60-70 litres than 19. These tiny tanks get marketed for beginners and kids but in all honesty, they're rubbish!