Yes I am I’m from Rhode Island.
Texas here !
I’m not sure whether or not they 100% replenish the elements (I haven’t tested my water in over 4 years besides salinity) that being said they do replenish depleted levels.
I go with a 5 gallon water change for my 32 gallon biocube and it has always done the job!
I do have Hanna phosphate checker and Salifert nitrate. I don’t mind testing 3 things but after three I lose my patience