algae in HOB tubes
I am new at this, and have a tank that's been up for a few months. I tried to clean my HOB filter tubes yesterday. They were very brown with diatoms. Recent purchase of some Otos have done miracles for the tank, but they can't get up into the tubes for the filter. I took the filter parts all apart yesterday, and was able to use a toothbrush on the inside of most of the tubes. However, the upper part of my AquaClear 20 filter is horizontal, and I can't take it apart any further, and can't get anything in there to remove the diatoms. I tried a pipe cleaner and some pieces of heavy yarn moved back and forth. Nothing I tried did anything. Still have this ugly brown stuff in the top, horizontal tube.
Is there a special tool or something I am unaware of that will work to clean out the part of the tubes that is not easily accessible?