Why are my plants “melting”?

In my aquarium plants seem to either thrive or vaporise in 2 weeks. I’ve had one plant now for 2 years which is thriving (and so is the hair algae that’s recently started covering it’s leaves) but 2 other plants recently disintegrated within 3/4 weeks of purchasing them and a replacement plant I bought last week is already shedding leaves, though oddly it’s also growing in height very quickly.

I’ve attached a photo, it’s the plant with the basil-like leaves.

I have the lights on for 5 hours a day and the same amount of time for CO2 gas.

Neonlights said:

a replacement plant I bought last week is already shedding leaves, though oddly it’s also growing in height very quickly

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There could be a few possibilities for what's causing that, plants you buy may be in an emersed state and are changing to a submerged state when you plant them, so old leafs die off. The light levels look bright from those pics which the plants are enjoying so older and lower-down leafs aren't getting as much lighting which will eventually = in die off. The plant will most of the time put its energy into new growth, closest to the light especially stem plants.

Also what sort of substrate do you have? And how thick is it? I've recently learned about the impact an anaerobic substrate can have on plants. Some say its beneficial others disagree but that's another topic of conversation But if your plants are rooted in well there's a small chance that it's caused by that.

Nice looking tank too. Full pic by any chance?

Any idea what the plant is called (the one that is melting)?
It could be a garden plant. Most aquarium plants sold in shops are grown out of water and shed their terrestrial leaves when put underwater.

Increase the lighting time to at least 8 hours per day. Plants need more than 5 hours light.

Have the CO2 come on when the lights come on and go off an hour before lights out so the plants can use the excess CO2 before it gets dark.

The filamentous algae is probably due to excess nutrients, however you have a lot of plants so unless you are adding lots of fertiliser, it shouldn't be a fertiliser issue.

Do you do a big water change before adding more fertiliser?
If not, you could have an imbalance in the nutrients that would encourage algae.

Colin_T said:

Any idea what the plant is called (the one that is melting)?

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If its the one in the pic it looks like Ludwigia palustris green to me

MattW said:

There could be a few possibilities for what's causing that, plants you buy may be in an emersed state and are changing to a submerged state when you plant them, so old leafs die off. The light levels look bright from those pics which the plants are enjoying so older and lower-down leafs aren't getting as much lighting which will eventually = in die off. The plant will most of the time put its energy into new growth, closest to the light especially stem plants.

Also what sort of substrate do you have? And how thick is it? I've recently learned about the impact an anaerobic substrate can have on plants. Some say its beneficial others disagree but that's another topic of conversation But if your plants are rooted in well there's a small chance that it's caused by that.

Nice looking tank too. Full pic by any chance?

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Thanks for getting back to me. The substrate is just aquarium sand.

This particular plant is doing well in terms of growth but the previous two literally disintegrated in a matter of weeks and that’s the issue/problem that I need to solve.

Colin_T said:

Any idea what the plant is called (the one that is melting)?
It could be a garden plant. Most aquarium plants sold in shops are grown out of water and shed their terrestrial leaves when put underwater.

Increase the lighting time to at least 8 hours per day. Plants need more than 5 hours light.

Have the CO2 come on when the lights come on and go off an hour before lights out so the plants can use the excess CO2 before it gets dark.

The filamentous algae is probably due to excess nutrients, however you have a lot of plants so unless you are adding lots of fertiliser, it shouldn't be a fertiliser issue.

Do you do a big water change before adding more fertiliser?
If not, you could have an imbalance in the nutrients that would encourage algae.

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Thanks for the response.

Unfortunately I don’t know the name of this plant or the previous two which vanished.

I only have 5 hrs of light as the aquarium is in the kitchen in a sunny spot so it gets a lot of light/non-direct sunlight, especially this time of year. The CO2 comes on 1hr before the lights come on and goes off 1hr before the lights do.

I do a 30% water change once a week and when adding the new water, along with dechlorinator, I add Leaf Zone for the plants and Stabilizer.

MattW said:

Ludwigia palustris green

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I think you could be the right, the leaves toward the top of the plant are developing an auburn tint.

MattW said:

Nice looking tank too. Full pic by any chance?

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As requested

Neonlights said:

As requested

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Looks like a really healthy tank! The plants look really healthy and bushy which is a great sign, a little bit of algae but that's to be expected you should see my 90L it's like a green thread factory at the moment You could try some floating plants? they would feed on the nutrients that the algae currently feed on.
Just avoid duckweed if possible if you know you know..

I'm sure @Fishmanic would like to see this in a future TOTM

MattW said:

Looks like a really healthy tank! The plants look really healthy and bushy which is a great sign, a little bit of algae but that's to be expected you should see my 90L it's like a green thread factory at the moment You could try some floating plants? they would feed on the nutrients that the algae currently feed on.
Just avoid duckweed if possible if you know you know..

I'm sure @Fishmanic would like to see this in a future TOTM

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Thanks! This is my first planted tank and I’ve had it a little over a year. Everyone who comes to the house loves it but when I look at it I always see the issues (algae, snails, CO2 diffuser clogging up), but I expect a lot of people here are the same with theirs, lol.

I tried floating plants twice and both times they also disintegrated within a week.

Neonlights said:

Thanks! This is my first planted tank and I’ve had it a little over a year. Everyone who comes to the house loves it but when I look at it I always see the issues (algae, snails, CO2 diffuser clogging up), but I expect a lot of people here are the same with theirs, lol.

I tried floating plants twice and both times they also disintegrated within a week.

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I think it's a beutiful scape. I was the same with my first few planted tanks I hated that alage ruined the look of the scape but now I've just accepted it. It makes my tanks look a lot more natural. The only thing I can't stand is unclean glass I don't mind algae on hardscape or plants but not the glass

Oof.. Do you have a lid on your tank? In my old scape, the water level was only an inch from the rim and floating plants always died, I dropped it to two inches and they thrived. Could even be the light that caused them to disintergrate? If it is too close that is

MattW said:

I think it's a beutiful scape. I was the same with my first few planted tanks I hated that alage ruined the look of the scape but now I've just accepted it. It makes my tanks look a lot more natural. The only thing I can't stand is unclean glass I don't mind algae on hardscape or plants but not the glass

Oof.. Do you have a lid on your tank? In my old scape, the water level was only an inch from the rim and floating plants always died, I dropped it to two inches and they thrived. Could even be the light that caused them to disintergrate? If it is too close that is

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Hi, I do have a glass lid on the tank, and your theory would explain why my two attempts at having floating plants ended with them disintegrating within a week. If I drop the level though it won’t look as good though so I’ll keep it as it is.

Neonlights said:

Hi, I do have a glass lid on the tank, and your theory would explain why my two attempts at having floating plants ended with them disintegrating within a week. If I drop the level though it won’t look as good though so I’ll keep it as it is.

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Any idea which floating plants you tried? Could be worth trying others. I have no issues with growing amazon frogbit or water lettuce in my tanks (or duckweed... even though I try so hard not to grow that! Yes Matt, I'm one of the ones that IYKTK!) But, I've tried to get ed root floaters to survive in my tanks many times, and each time, it melts back to nothing. Tried different tanks, grown in-vitro or bigger plants from other hobbyists tanks who found themselves throwing away fist fulls of red root floaters each week, because it grew so well for them... but they all just died either instantly or within weeks in my tanks.

One day! One day, I will have my RRFs, and they will grow, darn it!

So if one type didn't work for you, worth trying another! Some of them, like RRFs, don't like too much surface disturbance, especially if it means their leaves are often wet from spray and droplets of water.