Well, yes it is, there is less margin for error - however if you are dedicated and do good weekly water changes then it is do-able. However let me warn you, this is a very addictive hobby and you will not be happy for very long with such a limited tank
most of us upgrade very quickly which then costs us probably more in the long run
If i were you I would maybe think about getting a larger tank of approx 125 litres, second hand - you wouldnt regret it, but you will probably regret setting up such a small tank and quite quickly.
Have a read of some of the journels in the Marine Journel section and start making some plans. If you decide to go with the small tank we will be happy to help you
Seffie x