You should buy your sister a gift subscription to Pond Boss magazine - Birthday, Chrismas, Valentines day or just because you love her and use her pond,,, being you are the good brother you are.
http://www.pondboss.com/subscribe.aspOr you get the subscription and give her your copies after reading and learning. Currrent issue Mar-Apr 2013 talks about aeration start up time. Lots of variables about aeration specifics in your sister's, yours or anyone's situation. If you go by the advice of most professionals they will say run it all the time and this is more true the further south (warmer) your pond location. Generally start running the aerator when water temperatures reach 50F and stop with they reach 50F in the fall - exceptions to this rule occur. IMO if one is concerned about running 24/7 then it is better to run one longer period compared to two or several times per day because the longer run time results in a more complete pond turnover. This general rule applies ONLY if the aerator can turn over the pond several times a day. If the aerator cannot achieve one turnover a day then 24/7 aeration is generally the rule to follow.
