the algae extract did work for my pond, so i disagree with that.
i did also dose with hydrogen peroxide which worked quicker but it bleached equipment and left a brown crust so i stopped using it.
what works better than anything is algaefix, instant cure all lol, but its dangerous. and you have to realize algae in a pond is kinda inevitable...in the aquarium its easier to prevent and control
my pond has a bottom drain now and it seems to help alot more than when i didnt have one, even with my 80 watt UV, string algae is still possible so im always on the look out for the first signs
I've seen ponds go from green to clear without adding anything also.
So was it due to the extract? Who knows, unless there's some control or independence, you cannot say.
If it's a surface algae that coats things, try percarbonate, toss it on and it will sink and fry any algae off the rock etc.
Basically dry H2O2.
No no no! Pond algae is not always a sure thing.
I've been helping folks do this for decades without anything other than plants. Good flow(prevention of stratification) is very helpful.
UV's are fine, but I have never needed one for a pond.
Just 30-50% coverage with plants. Clear water, no algae.
Same approach for planted tanks works as well.
Every pond/lake I've worked on has no algae issues, not just for a few weeks etc, but for the life then on.
The trade off is that the plants need culled and pruned back once every 1-2 months during the warmer growth season so they do not take over the entire pond.
Very easy to care for if you have 1000-10,000 gal pond.
Also helps save koi/goldfish etc from birds etc since the fish can hide under the plants, having a few lilies is often what I see, which offers little cover and hardly any export. Plants block the light, which also cools the water, and blocks the light that algae use to grow really fast.
This is a very well known and researched results based on Florida lakes(7800 are 4 hectares or larger) of which are very similar to many planted ponds.
The lakes are clear where there is 30-50% coverage.
Several researchers looked at Barley also, in the USA few found results in controlled studies they did. In the UK, they had more positive results.
But there is no consensus amongst the research by any stretch.
Regards,
Tom Barr