As a rank amateur and the one who has to unblock the damn thing I'm inclined to agree with you there. :-)
I should have mentioned, the inlet pipe had a few inches lopped off it soon after taking those photos.That helped a lot, but obviously it's now at the stage where the sludge build-up combined with the poor design is causing repeated blockages in the inlet area.
From what I can see, the outlet pipe from the second tank is also too high.
Indeed. I assume that it would, generally speaking, be a major undertaking to lower the outlet of the second tank?
Or is there any way that it could be 'fudged' or 'artificially' lowered so that the water level in both tanks is kept lower and hence resulting in less bockages in the first tank's inlet area?
Have now booked it to be emptied tomorrow morning.