First, this is my internal overflow box for my sump:



This is the view from the front: (not current tank obviously!!)



Here is my issue, at the bottom of this overflow box there are slits in the plastic to pull in water and yuck stuff. There is a lot of the yuck stuff inside there. When the sump is off for cleaning, all this filmy yuck comes out into the tank. There is also a pile of sand in there from when I had sand instead of gravel.

As you can see from the top the gap between the outer plastic and the inner plastic wall is thin - very thin.

1. Do I need to leave this yuck in this tiny compartment?
2. Is the yuck part of my bioload?
3. If I can clean it out without messing up things, any suggestions on how to get down in there to clean it?

The inner partition wall is NOT removable. I have tried to suck it out from the outside of the box through the slits with no luck.

Thanks in advance!

Brooksie

all we can think of is using a pipe cleaner (The ones you can get for cleaning babybottles) and wipe the mess while keeping the hose for syphoning the water out during a waterchange close to the spots you wipe.

This yucky stuff will not be nescecary for your bacteria colony, and finding a way to clean it out wouldt be good.
I do flush any cravices in my tank and wood from time to time, and i syphon it out of the dirt afterwards after i let it settle for a while..
But that way you get a snowglobe effect for quite some time...

gunk and craps can easily be blown away by pressurized water.....
you can use the filter pump to spray it out by squeezing the discharge
hose in it.... or a pressure in your tap with hose will do...

I don't think I want to blow it out... the tank is full and occupied. I'm thinking of trying to use an air hose and find a way to attach it to my wet vac and suck it out. If I don't need the sand/yuck to maintain my bioload. I still have everything in the sump - filter material, bio balls, sponge - that would be full of the bacteria needed.

i know what you mean...but directing the discharge of your filter in that
area will blown the yucks/sand away in that area... yes, it will create some
cloudiness in your tank but eventually will clear up too and the gunk will
be carried away by the filter...

i believe vacuuming is not a good option.... unless you have a small
long hose that can be used as siphon where you can direct the suction
end in those area.... siphon acts like vacuum...