well you can build a sea wall to prevent erosion, groynes to stop long-shore drift, obviously no litter.
Obviously depends on the tanks size.
To determine if you have four generations in your family, you would need to identify family members from four consecutive age groups. For example, great-grandparents, grandparents, parents, and children. If all these generations are present and alive in your family, then you have four generations.
generation counting is the same everywhere. Grandma dad me is three generations, great-grandpa grandma mom me is four generations, grandpa mom me my baby is four generations. Generation counting does not have to be all one gender.
There are four generations from Rahab to Jesus in the genealogy.
What career changes for dental assistants took place over four generations? 
Wind, Saltwater, Seagulls and Sand in their Underwear.
His focus on common themes
Well certinly not in the firest four generations
There were four generations (including Levi). Moses was his great grandson Please look at the related link below.
Four that have been released, and they are making a fifth currently.
However many generations they wish. In general it cannot be more than four or five due to the Rule of Perpetuities.
"Four tells the future to gain."