hey michael,
your question very hard to answer leh.
If you want your tank looking clean and clear, then it is a must have.
If you do not mind your water looking slightly yellowish and willing to do religious WC, then it is a good to have.
Personal opinion, Actually the cost is not much.
a bottle of chemipure about $10+ can last you about 2-3 months.
So it will be better to have it than not to.
the benefit outweighs the cost.
hope this help bro!