you could get his urine tested by your Vet to see what his PH is, but the only way to get the urine more alkaline is by wet food
. YOu can also get his urine
sample to see if theres an infection
present at the same time
as far as cleaners, there are a few enzyme cleaners avail at good pet stores is this what you've used? the one I like the best is called Fizz or something its a table you mix with water.
theres also Urine Erase, Natures Miracle etc.....