dont use that proper pH crap its useless....use baking soda (washing soda may be better but its a little bit more tricky to find or dose) as it has a pH of 12, add it in small increments (like dripping kalk)
heres a calculator to know how much to add and its effect its mostly for ca/alk but youll see its effect on pH
For fresh water tank, I battle algae bloom with duckweed just like water treatment plants. It take away alot of the sulfate and compete with the aglae for nutrients. But anyone knows if there is a salt water version of the same plant?