was at a party this 4th and a person there build ponds & pools for a living.
He said he was told years ago to use Hydrogen Peroxide in the
pond to get rid of string algea.

He said it doesn't hurt the fish has used it in his own large pond for years.
He said he only puts it in when the problem starts, and that you see it work fast.
He said just go buy the really big bottles from Costco and that all those other
products on the market break down into HP anyway.

Has any of you ever heard of this or used it?

No, I never heard of hydrogen peroxide as algae cure, but that doesn't mean it isn't possible. What is the dosage he is using normally?

I normally would recommend koi clay as algae remover - I heard nothing but good things about it.

No, I never heard of hydrogen peroxide as algae cure, but that doesn't mean it isn't possible. What is the dosage he is using normally?

I normally would recommend koi clay as algae remover - I heard nothing but good things about it.

my pond is about 500 gal. so he said to start with 2-3 of those really big bottles. I have not gone to costco yet to see how big the bottles are. He said pour it along the rock edges where I see the algea stuck to the stone and in a day or to I would see it float off, that it kills off where it grows, the root. He said to watch it doesn't clog the filter that it works that fast.

FYI, for any that read this. I tested this out with a small bottle of HP yesterday. I pored it on the large rock edges that were covered with algea at the water line.

It is all gone! in one day! the stones are so clean it looks like the first day they were put in. There is not a single trace of algea on them. When I tested the water it was fine (but I used a small bottle)

I am going to get the large bottles this week end and do a little at a time while I test the water for this experiment, but so far so good.

sweet I just had a green water probem but no string algae yet.

Seems like it could be dangerous if you dose too high. I have done peroxide dips on fish before, and although it is diluted, it does strip their slime coat off and can stress them. It also seems that it could kill off your beneficial bacteria.

so far so good! I used two 32 oz bottles. The water readings are good, and they string algea is gone! The pond is looking more like when we first put it in. I think I found my miricle cheap cure!

Just be careful when you use this regimen.
Hydrogen peroxide is an oxidizer so it also will burn off some of the organic content of your water. Since it is working so well for you now...you want too keep it up , but that would be wrong ...at least at the strength you are using it at.
Let me explain. When you dump it into your pond it burns off/ reacts with some of the organic content of your pond. Meaning algae, mulm, decay, old fish slime, poop, etc. You get the idea. But now that your water is cleaner it will stay active in the water longer, and at a stronger strength potentially oxidizing not only the algae and organics but also your fishes slime coat and delicate gill membranes.
So be careful when going forward using this chemical as the more you use it, the stronger it will get. It is no different than pottasium permanganate in that regard. If you have ever used that chem to dose your pond, you will notice it gets expended quite quickly. But each subsequent dose is stronger.
HP also drops the bottom out of your ORP.
Works well on string algae though

thanks Rob, I printed your responce and will keep an eye on things