I'd take the sump offline while you're doing the change and try to replace all the water in the sump before turning the return pump back on. It's definitely gonna release some nasty stuff you dont want getting to the main tank.
Going to clean my sump out was thinking about replacing the fuge sand bed going to suck out the top layer do I replace the whole thing or just want I remove ?
Why change the sand bed ? the sand bed has all that good bacteria that has been growing in it ... no?
why change the sand bed ? The sand bed has all that good bacteria that has been growing in it ... No?
Once a sandbed starts getting old, it is a good idea to replace them as they do trap detritus over time. If you have ever seen an old sandbed stirred up you get a 'cloud' of very fine particles that are released.
In Jeremy's tank he also has all the good bacteria still in his live rock and sand in his DT - the sump fuge sand will repopulate quickly.
Some folks will also replace the sandbed in their DT every now & then by doing it in sections...about 1/6th every week until it has all new sand.