How to fix black leaf edges for Aztec Arrowhead (sagittaria montividensis)?

[Waleed K]

I have some Aztec arrowheads in my small pond (100 gallons), but they don't seem to be doing so well. Their leaves are turning black from the outside in.

Since I took this photo, they're doing much worse.

My pond currently:
- Nice warm weather currently (around 55-85F).
- 5 goldfish, about 30 rosy red minnows, 50 mosquitofish.
- pH slightly on the high side (7.5 in the morning, 8.5 in the midday heat).
- Very hard water (KH > 250ppm).
- Lots of sun (though the plants that get more sun seem to be doing slightly better).

Any thoughts on causes and/or remedies?

 

[sissy]

water temp. may not be good or take them out and put them in a tube of water with a little miracle grow

 

[Waleed K]

Thanks for the reply! Really appreciate the suggestion. Will give this a shot and report back.

What water temperature do they usually prefer? Here's the latest photo, seems to be getting worse.

 

[Faebinder]

I think they don't like the crown to be wet. Make the pot higher.