Yes!! i see this post is over a year old but yes, not only do nausturtiums thrive in water, they actually filter, clarify and oxygenate the water. the same is said to be true of other pond plants and flowers like water lillies! you can put the whole nursery planter(topped with perlite) in the water or you can just tuck in little bunches of plant with roots amongst the rocks!! if just tucking in amongst the rocks just be sure to check that the roots are hearty.. i know someone who has Koi fish and they are 11 years old. she does not have a filteration system, she just uses pond plants and flowers. shes had the koi’s since they were 1 and she winters them inside during colder weather. by the way did they work out for you last year?

I saved nasturtium seeds of mixed colors, the seeds produced mixed colors, mostly yellows and oranges. I like the red ones too, so this year I will plant Empress of India, which is really more of an orange-ish red, but still pretty and very bright and eye catching. I'm going to save the seed from them too, just to see what I get. Nasturtium seed does come in a lot of beautiful colors now - peach, soft yellow, coral, bright pink but you'll need to buy the seeds to get those colors, I've never had them reseed into anything but oranges and yellows, but its worth a try to save the seeds just to see what they look like.

and yet.. when i googled it.. it said they were annuals.. go figure.... heres the link.. i relied on the first link below the ads ... https://duckduckgo.com/?t=ffcm&q=nasturtium&ia=web further down it says they are annuals and perenials ... whatever ... but it might depend on where OP is.. and which N she wants to grow ... instead of waiting... heres what else i was thinking... if you are getting a jump start on planting them outdoors next spring.. you might try starting see 4 to 6 weeks before they can go outside ... so you have rather young vigorous plants to go out ... if you start too soon indoors.. with the lack of light.. you will end up with etoliated ugly plants.. that will not transplant outside easily ... if you are trying to grow them as house plants... it may or may not work.. depending on light levels as flora noted .. and for sure what she said.. why not experiment.. its just a pack of seeds and some media .. etc .. it will be a nice winter hobby seeing what happens ... ken

big city location ... is usually helpful if a plant continues to flower.. i guess is wouldnot say they are destroyed.. regardless of how ugly they may get ... do you expect them to live forever??...is winter coming where you are ... what has the weather been like since this started???.. and hail storms or some such?? other than a pic of slight damage.. you havent given us much to work with ... and if you cant find a bug day or night.. then it probably isnt a bug .. and that doesnt look like a disease off hand.. so i am leaning toward mechanical ... something is beating up the leaves ... ken ps: have you looked for bugs at night?