It's nice to see the fish. At last, after a year of green water! Light levels and temperature have dropped now, and the green water has faded. While fish don't appear to mind swimming in this green fog (as long as the water quality is good), there's no doubt that they are tamer when the water is clear, and come up to you when you offer food.
We've tried a couple of remedies this year to clear the water- a chemical algicide which had modest short term benefit but generated lots of unsightly floating rafts of dead algae. I didn't particularly like using this, having some concerns over fish health (although all was well). And an eco product, which made me feel better but which had no obvious effect whatsoever. We stopped using it around two months ago, so I'm not sure it can lay claim to the current clear water! Neither of these will feature in next year's shopping list but one product which might have helped was a course of 'sludge-buster' tablets which had no obvious benefit at the time other than causing partly decomposing leaves to rise to the surface. If this did work, it would have reduced the amount of decomposing matter on the bottom of the pond, and that would have contributed, over time, to less algae, as there would be less for it to 'feed' on.
So what did make the most impact? What started to clear the water? Well, during the really hot spell, to save time, we started to use the goldfish pond as a dipping pond for the pots round about, removing around 35 watering cans of pond water twice a week, then refilling the pond with a rather slow hosepipe. Thus will have equated to approx 100 gallons per week, just shy of 1/6 volume of our pond, split over two sessions. It didn't create crystal clear water, but it certainly improved the situation, and it's a proactive we'll continue next year.
Nb/our water supply is low in chlorine. We also had the fountain on when we refilled the pond to help defray any chemicals in the supply. We would strongly recommend a pond declorinator/ new water treatment if following a similar procedure.