tbh doesnt look like root rot at all. plants look fine, except maybe for some cal-mag deficiency (seen from the brown spots). those yellow roots are the result of light penetrating into the water tank.
if indeed if a case of bud rot changing water won't do anything. you need to take out everything and sterilize everything (tank, airstones, tubes etc). otherwise bud rot will come up again.
for sterilization you can use H2O2 (hydrogen peroxide) or bleach (but be sure to was heverything very well after).
if indeed if a case of bud rot changing water won't do anything. you need to take out everything and sterilize everything (tank, airstones, tubes etc). otherwise bud rot will come up again.
for sterilization you can use H2O2 (hydrogen peroxide) or bleach (but be sure to was heverything very well after).