Water changes have little effect on phosphates . But changing water with significantly lower Alk will lower it , but could lower too fast ( any more than .5 dkh swing per day isn’t good .
if you have coralline algae or other lps or sps corals , they might consume some Alk
Keep a eye on it . Small water changes will put you back on track but try not to upset anything too much .
Slow down , research and know what every product you’re dosing and it’s effects on everything else .
if you’re unsure , feel free to ask
the best advice I can offer .
don’t dose anything to your system if you can’t test the need for it.
And know when you’re adjusting one element . You’re most likely effecting others as well