The age of a tank doesn't determine necessity/frequency of water changes. That needs to be based on individualized testing/tracking. Just going off your info here its 100% a trate/phosphate problem. Get some testing done, figure out what your nitrates are at then you can formulate a plan. We had brown algae starting to rear its head in our 125 so I went no light for several days and then gravel vacd out the problem areas and slowly added light back. Seems to have worked. Its much easier just to establish a solid weekly
wc routine now and it'll become habit quickly (I've got a
wc tomorrow now that I think of it)