Thanks D for the nod, 180 gallon is a bit too small for 3 cuttlefish, mostly it comes down to dimensions of the tank too as if they don't have enough space you will find cuttlebone fractures and infection. As for the other questions 73-74 degrees is too warm for them as you will go through huge amounts of food at this temperature plus they will mature faster. I would normally keep them around 62 which is the median sort of temperature for these guys around my coastline. As for a sandbed, yes you will need one but unless you are planning on syphoning on a daily basis then I would recommend not making it too deep otherwise again you can get bacterial infections going on. They are a lot of work and grow rather large, If you have not kept cuttlefish before then I would not suggest this species as a starting species.