It sux that you cant get locally,I am new to reefing but I would cut that in half and see how that works you dont want anythig dieing and you wont know,I siphon once a week and its not too dirty those nass snails are no joke as soon as you feed the tank you see them pop out,the two trochus i have eat algae like you wont believe.You can always add more if you need.