Hello friend.
I had the same issue in my RS-525. It lasted for months trying to do it the pick and add things way. I removed as much by hand as I could get and then used a tooth brush to brush the rocks. I then used a siphon from DT into sump but ran the water thru the filter sock so I wasn’t doing a massive water change but would keep filtering what was rubbed off.
Then I used attached picture and followed the direction. Turn off skimmer for 2 weeks during this process. Mix it in a bowl and then add to your DT. After 10 days I did a 3 day black out at the very end (turned off all lights) and only allowed natural light in. At the 14 day period it was all gone then I did another brush with tooth brush and a 20% water change. It literally got it all out (100%).
The first time I tried it a few months ago I didn’t do all the steps in the paragraph above. I only mixed and added and waited and it helped but didn’t remove all. The second attempt above with all the cleaning before and the black out worked 100% for me.
This DID NOT AFFECT MY FISH OR CORALS.
Hope this helps. You can search my name and see I posted about this a few times to others.
I had the same issue in my RS-525. It lasted for months trying to do it the pick and add things way. I removed as much by hand as I could get and then used a tooth brush to brush the rocks. I then used a siphon from DT into sump but ran the water thru the filter sock so I wasn’t doing a massive water change but would keep filtering what was rubbed off.
Then I used attached picture and followed the direction. Turn off skimmer for 2 weeks during this process. Mix it in a bowl and then add to your DT. After 10 days I did a 3 day black out at the very end (turned off all lights) and only allowed natural light in. At the 14 day period it was all gone then I did another brush with tooth brush and a 20% water change. It literally got it all out (100%).
The first time I tried it a few months ago I didn’t do all the steps in the paragraph above. I only mixed and added and waited and it helped but didn’t remove all. The second attempt above with all the cleaning before and the black out worked 100% for me.
This DID NOT AFFECT MY FISH OR CORALS.
Hope this helps. You can search my name and see I posted about this a few times to others.