Can string algae kill plants?

[GSD]

Im having the worst time with plants. The water hyacinths i bought have begun to die. Black spots all over them. I cut all the bad spots off, washed them in peroxide/water and now they're out of the pond in a thing of water with miracle grow (read online that this method has saved some people's w/h)

My question tho is can string algae choke them out? Their roots were covered in it. I got into the pond today and got as much string algae as I could out of the pond, also have been adding barley extract but honestly, ive seen zero results. This stuff grows incredibly FAST and doesnt seem like its inhibiting its growth at all. Im about to use chemicals but gotta say, im not sure which one works the best and is the safest. Pretty nervous using chemicals.

I seem to have the WORST luck with pond plants, even the ones they say you cant kill. (hyacinths & lettuce and lillies )

and i know theres nutrition in the water otherwise this **** string algae wouldnt be going crazy!

Can someone offer some advice? Ty

[*Ci*]

String algae will definitely choke out plants and also outcompetes plants for available nutrients.
Barley straw, when it decomposes, adds small amounts of hydrogen peroxide (HP) to the water which inhibits algae, but it is not sufficient when there is already a significant outbreak. You might consider adding more HP to kill off what is already there. Some threads of note that have good info on dosing:

First experience with Hydrogen peroxide

Help re string algae

[Paul Sabucchi]

Only caveat I would add is that if you have tons of string algae killing them all at once may also be a bit of a problem because this will cause a sudden release of all the waste substances that were taken up by the algae. So it is often better to keep hitting them a bit at a time with repeated lower doses of peroxide, or as I would do is use a product like Colombo's Algisin (I don't know if it is available outside Europe) that is not super potent at the recommended dose and keep using it at weekly intervals

[GSD]

Yeah i definitely think that's what it did to the hyacinths. Their roots were completely covered in it.

I think im just going to bite the bullet, buy some d-solv or algaeoff and hope everything goes ok. I removed a lottttt of it, but now that the water has cleared up i can see areas i need to remove more from but after that, im gonna try the algaecide. I cant remember which one my local store has but i know it was one of those 2 and both are copper free so i think that makes it safer.. ?

[*Ci*]

Personally, I think that hydrogen peroxide is a much safer bet than an algaecide, and would try it first. I also agree with killing the algae off slowly, and removing or filtering out the dead material as you go - this will help prevent an ammonia spike, as well (the string algae is likely consuming a lot of ammonia and your biofilter will need to catch up once it is gone).

[GSD]

According to google, id need ½c of 3% hydrogen peroxide per 100 gallons. If this is correct, with about 2250g, I'll need 12½ cups.. can someone confirm if the ratio of ½c for 100 gallons is correct? and also check my math, please? And ty Lol