Farmer, John Charles Barnett of Tybroughton near Whitchurch, just across the Welsh/Shropshire border, died on January 2, 2020.
The inquest heard that Mr Barnett's heavy mobility scooter was tipped over on its side, close to the slurry lagoon.
The pensioner’s body was found by a police diver hours later.
GP Dr Kieran Redman said in a statement that the pensioner had attempted suicide previously.
However his son, Robert Barnett, said the improvement in his father in 2019 was enormous and he had been in excellent spirits.
Mr Barnett, known as Charlie, visited a solicitor in Chester with his family on the afternoon of January 2, to change his will.
The inquest was told that his will included an inheritance of £20,000 for farm worker and friend, Mr Nigel Byrne with the remainder of his estate was to be divided between his son and daughter.
Senior coroner John Gittins heard that in 2012 a will had left Mr Byrne, Mr Barnett’s interest in a farmhouse and almost 60 acres of farmland.
Mr Robert Barnett, told the coroner the family wanted questions answered.
When Mr Gittins asked him if he believed there had been some foul play he said he honestly didn't know.
He said he was at his own home during the evening when there was a knock at the door and a local man told him his father was in the lagoon, a couple of minutes away.
“I was absolutely shocked, dazed and also very angry partly with myself. I said to Nigel ‘you have got a lot to answer for’.’ He just turned away.”
Daughter, Jennifer Parry-Jones told the coroner she left her father in his chair at 6.22pm and went home.
An hour later she had a missed call from Mr Byrne. When she returned the call she said: "He said ‘you better get back here quick. Your dad has gone loopy and he’s heading for the lagoon’.”
She said she believed Mr Byrne had harmed her father because her father had changed his will.
When questioned by the coroner she said she had definitely not harmed her father.