i recomend finding a different LFS. They are going to really hurt your tank. Or if no reputable around, feel free to ask people here as you are doing or even call and talk with some recomended online venders.
My understanding is they gave you "live rock" which was just rock that was just put in the system. They also gave you water to help "cycle" faster. Very little bacteria is in the water column. You can use it but you will know nothing of those parameters and what was depleted. Also if they are doing these things who knows what diseases your adding to tank. If the rock was in a running system for a day or 2, you will be alright.
I also see you have bacteria but nitrates should not already be that high. You can absolutly do 100 percent water change if you are using same salt mix and the temp is within a couple degrees.
they are also selling you fish that will outgrow or shouldnt be in that size tank. If they stated they would outgrow and to bring back is one thing. But if they didnt give you that warning at least, thats a no go.
Lots of good advice in thread and some different from mine but take what ever that LFS with a grain of salt..if even that.
My understanding is they gave you "live rock" which was just rock that was just put in the system. They also gave you water to help "cycle" faster. Very little bacteria is in the water column. You can use it but you will know nothing of those parameters and what was depleted. Also if they are doing these things who knows what diseases your adding to tank. If the rock was in a running system for a day or 2, you will be alright.
I also see you have bacteria but nitrates should not already be that high. You can absolutly do 100 percent water change if you are using same salt mix and the temp is within a couple degrees.
they are also selling you fish that will outgrow or shouldnt be in that size tank. If they stated they would outgrow and to bring back is one thing. But if they didnt give you that warning at least, thats a no go.
Lots of good advice in thread and some different from mine but take what ever that LFS with a grain of salt..if even that.