Hi I'm trying to set up a seahorse salt water tank and I can't decide what tanks to get, I will probably keep 2-4 lined sea horses and a Green Mandarin 1. A 35 gallon hexagon tank with a magnum 350 canister filter, heater, gravel and 35 pound of live rock.( this tank seems to be pretty thin but very tall) $100 2. A 55 gallon normal tank with a 50g and a 20g hang over filters, heater, lights plus 42 pounds of live rock. $120 3. A 150 gallon normal tank with a 150 pounds of dead living rock(would need to cure it? sump filter(older), light system and every thing else I would need. $260 Is $2 a pound plus $15 gas a good price for live rock? do I need live rock for sea horse if I have a sponge filter or a canister filter and lot of live sand?