Andy pretty well covered it. There is a check valve built in the shurflo 2088 pumps but a second won't hurt as back leakage thru the check valve can often be the answer to unexplained pump cycling.
My 50 year old steel tank is still doing fine
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Rick Davis 1602 K8DOC
61 tradewind, plus a few others
13 Ram 2500 TD
99 Dodge TD 577K miles
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