Imhoff bio tank issues

Hi all, back looking for some more awesome and much needed help!

We have inherited a plastic IMHOF biological tank for our black water treatment at our farmhouse in Italy, it was installed by the previous owner about ten years ago.

It seems to my basic knowledge that the tank isn't working as it should as there is always a thick layer of ERM...crap on the top of the water sandwiched between the top of the tank and the water level and at varying levels of decay I guess, the older stuff at the very top almost black and soil like, this layer being around four inches in all.

The tank is dug into the ground BUT the top is exposed to the Italian weather, including very hot summers, is this killing any bacteria inside and therefore giving us our problem?

Looking forward to your replies and thanks in advance.

Stu

I had to Google to figure out you were talking about an Imhoff tank.  

What is the actual problem?  I get that you have a layer of "stuff" floating in the tank, but is the tank backing up or failing to digest in the long run?

😂 sorry Dan, maybe the name was uneccessary.

Yes, basically it never digests, doesn't mmatter how much activator or what sort I put down there it just floats, fills, and then wants to back up, which it did to us a couple of years ago.

I can only think that the state our is in means there is zero digesting.

I helped a friend locate his tank recently, he bought a house four years ago and hadn't yet found the tank, when we did and opened it up I was not greeted with the same horror sshiw we have but a happily digesting tank, without doubt a fair sludge layer on the bottom but the top was clear.