Thanks guys, I really appreciate your input. As you probably guessed, I am doing what I can with what I have available. Your concerns on the use of bleach is noted. I was thinking of maybe putting a "T" at the end of the pipe and using 1" pipe with 1/4" holes or similar, to give a better spay area. Actually, the suction is at one end of the lagoon and the discharge towards the other, but can be aimed to induce some surface movement. The lagoon isn't that big and I am reluctant to get too aggressive as I don't want to wash out the sides/banks. I am sure what I am doing must be some help as the smell has all but gone and the green algae does not seem to be as thick (maybe wishful thinking on my part). I am trying not to spend too much money unless I absolutely have to. Also, I have been surprised in that the water pump seems to run all day on about 1.5 galls of gas. Around three litres last 3.5 hours run time. Any other suggestions would be greatly appreciated - and many thanks for comments thus far. I will stay with just circulating for now and leave the chemicals out. I like the suggestion of Sodium Percarbonate - need to do some reading up on it. Thx Jim