Tank Tech

Your opinion on Tank Tech Rx black water holding tank treatment. Arizona summer 100 degrees +, here due the medical issues.I have been using it for 1 month and it seems to do a little better then the others. The black fly issue, (very small black flies in the tank that fly out as we flush. We used aerosol bug spray in the toilet for 2 weeks once a day and the Rx, no more flies. What do you think, good, bad, etc. Thanks.