Do I really need a saltwater test kit?

[Dan_P]

Really quick question, do I need a saltwater test kit if I have premixed saltwater from a lfs, and I do weekly water changes? I don't see the need for them, if I detect something wrong with my water, i'll do a water change, and if I dont, i'll still do a water change. (nano tanks if that helps)

If you aren’t testing the water, how are you “detecting something wrong with the water”?

Small (10%) water changes can be useless for maintaining water quality. How are you going to determine what percent water to change every week?

Trusting someone else to make saltwater for you is tiresome, expensive and potentially risky.

Flying blind maintaining water quality might not be the wisest choice for your first (I assume) saltwater aquarium.