How large is the tank? If you can access the rock easily and remove, I would scrub all the hair algae off and rinse with saltwater to remove debris. The same can be said of the hair algae on the substrate.
That being said, this will only be a temporary fix. The hair algae will come back. You need to combine manual removal with checking your nutrient levels- you likely have too much phosphate/nitrate in your water driving your hair algae growth.
I would 1) focus on manual removal 1-2x per week, 2) check your nutrients and increase nutrient export either via water changes, skimmer, refugium, etc. and 3) you may think about increasing your clean up crew. I would do this last as it's the least effective, but will help in tandem with the other two options.
There are some other products offered that may help, but I don't think they would be good choices in this case, but to each their own
Young tanks go through "ugly" stages before maturing. Hair algae is one.
If using tap water, it isn't good as it adds TDS (total dissolved solids), heavy metals, fertilizer run off.....etc that fuels nuisance algaes. Using RO/DI (reverse osmosis/deionized water) removes all of this and provides nearly perfect clean water.
my tank has been set up for almost a year and a half but lately I’ve been using tap water but I just got a rodi. Should I just do a big water change and scrub my rocks? I’ve never scrubbed my rocks before how would I go about that?