I have been running a sulfur de-nitrator for about six months with good results. My question is how often should the sulfur be changed.Is it replaced when it is all dissolved ?
If you replace or clean media the process starts all over again. If it's still working with no issues let it keep running . There isn't a time frame for changing or servicing .
The sulfur should stay nice and yellow, otherwise, if you see dark or black areas, then there isn't sufficient flow traveling through and it'll need a definite replacement.