bitter cucumbers

[sammy65]

I have raised beds appx 3 x 8 and have grown various veggies in them over the last 5 years. Each time I try zuchinni or cucumbers the fruit is very bitter, even could be considered acidic.
I have rotated some items - tomatoes especially - and even dig 4-6 inches out every year adding in new compost and soil for each new crop.
What am I missing?
thanks!

[Intriguedbybonsai]

I found a link that may be helpful.

https://cru.cahe.wsu.edu/CEPublications/eb1250/eb1250.html