Black lily leaves: care and troubleshooting

[geniusOfSalt]

A couple of things to get out of the way:
1. I'm well aware I've got algae issues - no need to point that out.
2. No need to sound the alarm; if I lose this lily, the world won't come to an end (though the lily might).

I'm working on balancing out a tank with high pH and low nutrients - that's a whole other thread. To give my plants a boost, I added root fertilizer (Seachem, if that makes a difference) a couple of weeks ago. It's been working well for most of the plants, but the lily has taken a turn for the worse. Not sure what's going on - the leaves have gone black just as everything else is starting to take off.

If anyone's seen this before and knows what's up, I'd love to hear about it. I've had zero issues growing lilies in ponds for years, so this one's got me stumped. If not, no big deal - just thought I'd share the weirdness.

[farmhand]

"I'm curious, how close did you place the root fert tab to the lily? Was it right up against the roots or a bit of a distance away?"

[geniusOfSalt]

About 3-5cm from the lily.

[farmhand]

That distance seems reasonable, given the nutrient demands of bulbs. I'm now wondering if the issue at hand might be a manifestation of algae allelopathy, where the algae is releasing compounds that inhibit the growth of your lily.

[geniusOfSalt]

Thanks for the input, it's good to know the root tab distance isn't the issue. Lilies being nutrient-hungry isn't surprising, I've seen it in ponds too. It's interesting that it's similar in aquariums.

Regarding allelopathy, I'm not entirely convinced. It's often cited based on patterns, but without solid evidence, I'm skeptical. This isn't just a personal bias, but also a concern that it's frequently misattributed by both laymen and scientists. I'd need more concrete proof to consider it a viable explanation.

[farmhand]

That's perfectly fine, trust but verify as the saying goes. I brought it up because I've recently experienced something similar with my Microsorum pteropus "Windelov". The leaves started darkening from the base towards the tips just a few days after I introduced Egeria densa into the tank. It was quite impressive how quickly that happened. I ended up moving the java fern to another tank and it's now showing signs of recovery.

[geniusOfSalt]

"I'm curious, how close did you place the root fert tab to the lily? Was it right up against the roots or a bit of a distance away?"

That's a solid axiom.

farmhand said:

The reason I even brought it up is because I just went through something similar with my Microsorum pteropus "Windelov", when the leaves started darkening from the base towards the tips a mere few days after I introduced Egeria densa into the tank. Pretty impressive how fast that took place. I moved the java fern to another tank and it is now showing signs of recovery.

That's quite a unique pattern, and I've had success growing those two together in the past. Glad to hear the java fern's bouncing back, whatever the cause was.

[geniusOfSalt]

Update: So I've got a bit of a reversal on my hands - the lily was bouncing back, and then out of nowhere, it starts shedding leaves again. Same symptoms, same appearance. This time, though, I was able to pinpoint a potential cause: my H2O2 treatment for staghorn algae from yesterday.

It seems the lily's got a pretty low tolerance for this stuff - much like the staghorn itself, but unlike the green carpet algae, which just shrugs it off.

If you're planning on using H2O2 to tackle algae and you've got a water lily in the tank, just a heads up: it might be worth exercising some caution.