The closed loop repurposed to clean the sand

[hillegom]

I don't know about the closed loop.
What I want to comment on is your canister filter. If you leave detrius in the cannister more than 4 days/week, it will decompose and send the nutrients right back into the tank. Thats why people clean their filter socks regularly.
The other camp doesn't use filter socks and they let the detrius decompose anyway and let the skimmer pick up the DOCs
I run a small HOB with a filter and clean it out every 3-4 days. Nutrient export.
It takes me about 5 min.
There is a lot of ways to do detrius and I am sure someone else will chime in