3 days you say? well, i seriously hope you have learnt from your mistake and hence ended the torment and misery of the livestock. 3 weeks isn't enough if you ask me, i think anything less than 1 month isn't enough actually. the longer the better. before you contemplate on getting more ls, get more lr and more sand which will in turn benefit your biological filteration. but getting more lr would be as good as cycling you tank again. so yup. make your sandbed deeper, get more lr. cycle for another month. check your parameters. and if they're ideal, you're good to go. there is simply no reason to go about this hobby by trial and error with the abundant information available on the net. but making mistakes would be inevitable. hence, learn from them and you'll have a good time reefing. cheers.