i am sorry to say that it is misleading to tell the forum people that IT IS OKIE to keep SPS at 50ppmn of nitrate. The key here is not whether they live or die ...
They might not DIE , but i am quite sure they will not thrieve as well as they could.
On the other hand, i only change water occasionally as i realise that whenever i change water, my water parameter will fluactuate a bit for a while before it come to a stable value again. And also i would not advice reefer not to change water as every system is different with different equipments to ensure stability of ur water parameter.
I am plain lazy to change water, yet i like SPS, so to counter that, i just have to invest in better equipment.