question on water changes for tangs

[green m0ray]

i have 6 yellow tangs, 1 sabae anemone, and two percula clowns in a 100 gallon tank, none are large, just 2inches to 4inches. i do a 5 gallon water change every week to keep up water quality. i know my tank is not following the fish to gallon rule but plan on upgrading mid next year to a 150. is 5 gallons enough to keep my fish healthy or should i increase to 10 gallons a week? water is crystal clear. but i need to take it to a local pet shop to test it.
thanks

 

[exotickeeper]

People always stress water changes, but I don't do them. I just top off from RO water. Seven years and still going strong!!