dirty residual in instant host water hose

[30all]

The yellow rubber(neoprane?) hot water tube broke at the spot where connects to water tank after only 1 year of use of my instant hot water. I cut 1" at the end then I saw this disgusting green deposit inside the hose.

How can I rectify this problem? I don't even know how if this hot water tank needs to flush from time to time.
I have a 2 stage water filter installed before hot water tank

 

[WestcoastPlumber]

The yellow rubber(neoprane?) hot water tube broke at the spot where connects to water tank after only 1 year of use of my instant hot water. I cut 1" at the end then I saw this disgusting green deposit inside the hose.

How can I rectify this problem? I don't even know how if this hot water tank needs to flush from time to time.
I have a 2 stage water filter installed before hot water tank

You have a filter system and there is still muck inside the unit?? When was the last time you changed your filters??

After unplugging the unit, there should be a drain cock at the bottom of the unit.

Do not drain it and plug it in before you have turned the faucet on and flushed it empty of air.