I waited a good while before reviewing this product just to be sure of its performance ..... I can now confidently recommend it!
I only have a 'small', decorative pond to create a soothing sound feature of waterfall etc. It has a reputable pump/filter system, but for the last few years the algae problem has increased .... horrible green stringy gunge .... even the birds stopped bathing in it !
I gave this product a try mainly because it was a cheap alternative before getting more involved ..... Look No Further .... It's Great !
Safety-wise, my dogs still drink from the pond as do all the birds [ don't legally hold me to that !] and the results are wonderful .... I will be stocking up for an early start next Spring before the algae season kicks in !