Amazon sword leaves appear translucent, what's going on

[mumlius]

Hi Everyone,

Got a question about my Zorchzon swords - not too familiar with aquarium plants, so bear with me.

They're doing well, I think - got some flowering stalks growing out of the tank and loads of new leaves. The new leaves look healthy, but they're a bit transparent (still green, but I can see the shadow of my fingers through them, unlike the older leaves).

Is this normal for new leaves, or is something missing in the tank? I've got a 150L tank with 2 30w tubes (low light, I know) on for about 12 hours a day. I use Easy Life root sticks in the gravel. Water's hard (GH 19) and alkaline (pH 8.2). Ammonia and nitrite are zero, and nitrate's around 20ppm (tap water and my API kit's a bit tricky to read).

I've got small community fish - dwarf rainbows, zebra danios, bronze corys, and a pearl gourami. Any advice would be great, thanks!

[boomer]

What you've described doesn't necessarily raise any red flags, especially considering the plants are thriving and producing inflorescences. If the new leaves continue to develop and the plants remain healthy, I wouldn't be too concerned.

Regarding your lighting setup, I'd like to know more about the tubes you're using - are they T8 or T5, and what's the spectrum? The wattage and duration are a good starting point, but the type and spectrum of the tubes can make a significant difference.

I think you're on the right track with the substrate tabs, as swords are indeed heavy feeders. The fact that they're not getting into the upper water column reduces the likelihood of algae issues. I personally use Seachem's Flourish Tabs, but I'm sure the Easy Life tabs are similar, even if I couldn't find the exact ingredients on their website.

[coltin]

If you're not getting much algae, you could try increasing the photoperiod by a couple of hours to give the plants more light. I'd suggest adding an hour or two and seeing how the algae and plants respond.

[mumlius]

They're Interpet T8s, with a spectrum of around 660nm - I'm pretty sure that's in the red spectrum. I couldn't find a K rating in the manual, but they're listed as 780 lumens and 7,000 hours. I'm not sure how good they're supposed to be, but they came with the package so I didn't have much choice. I've been thinking of upgrading to T8 LEDs eventually, possibly the Arcadia ones with 8k - would that be an improvement?

[coltin]

Lights with 8K - that's too high for plants, in my opinion. You don't want anything above 6500K for aquatic plants, that's just overkill. I mean, 8K is more for marine tanks, making corals glow and all that. And 10,000K? That's basically ultraviolet light, causes sunburn and makes corals glow even more.

What you want is something similar to sunlight during the middle of the day, which has a 6500K rating. That's the sweet spot. As the Kelvin rating increases above 6500K, the light becomes more blue and ultraviolet dominant. And if it drops below 5500K, you get more red and yellow light, but less blue.

Plants need a mix of red and blue light to thrive. If they don't get both, they won't do as well. And here's the thing, lights also lose their Kelvin rating over time. So, a 6500K globe might be closer to 5500K after six months, and around 4500K after a year.

Most aquarium globes have a mix of red and blue light, but if you can get one with a 6500K rating, you'll be fine.

[mumlius]

Thanks to you both for the advice, it's really helpful as always.
I think I'll stick with my current lights and keep using the root tabs. Hopefully the new leaves will thicken up a bit as they grow.

I do have a bit of algae, which I clean off every few weeks - mainly just a green film on the glass and a few patches of black beard that I'm keeping an eye on. The tank's still settling in, it's only a few months old after all. I also think I might be overfeeding a bit, so I'm trying to cut down on that. It's hard to judge how much food they need, though - they gobble it up so quickly and they've got me trained to feed them on demand!

[coltin]

I think I over feed a bit, making a conscious effort to cut down but it's hard to judge how much they need as the demolish food so quickly. Their begging routine is down to a fine art now. I swear, they've got me trained - the minute I walk near the tank, they're swimming up to the glass, mouths open, expecting to be fed. It's quite amusing, but I know I need to be more disciplined.