Brown older leaves in a low tech tank

[alext8]

Hello, this is my first tank (55L low tech), and it's been setup for around 5 months now. To start with I was getting really good growth, but over the last 2-3 months I've noticed that only the newer growth is green on most plants. The older leaves are brown and unhealthy, and I'm not sure why.

While the browning is most obvious in the limnophilia, it's also noticeable on the rotala and the foreground plants.

I've also noticed that the stem plants are growing much slower than before. When I first setup the tank, the limnophilia would grow rapidly. But I trimmed some of it back a couple of weeks ago and there's barely been any regrowth since. Even the salvinia seems to be spreading much less rapidly - I haven't had to remove any for ages. When I first added it to the tank it seemed to multiply like crazy.

Things I've tried:

• At first I thought it might be algae, so I reduced the lighting to around 6 hours per day and stopped dosing. This didn't help, so I switched back to using API Leaf Zone once a week.
• Then I thought it might not be enough light. There's no dimmer on my light, so I tried moving it a bit closer to the tank. No improvement.
• Then I thought it might be a nutrient deficiency, so I started using NT Labs Plant Boost + Liquid CO2 Boost instead around 4 weeks ago, but again no improvement.

I'm now wondering if it's an issue with the flow in the tank? Or possibly a build-up of organics? I do weekly water changes, but I don't always rinse the filters. Should I rinse both the sponge filters and ceramic media?

I'd really appreciate any help. Thanks in advance!

1. Size of tank - 55 litres.
2. Age of the system approximately - 5 months
3. Tap water parameters - According to South East Water, I live in a hard water area - 2.22 mmol/l. When I last tested the tank, GH 196 and KH 125.
4. Filtration - I'm using the Aqua Nano 40 which has a filter compartment at the back containing a large coarse sponge, a big bag of ceramic media, and a smaller sponge. The pump flow can be adjusted, but I've got it set to the lowest otherwise the flow seems way too strong for my guppies. I also recently added a submersed spray bar angled upwards for a bit more surface agitation (around 10 days ago), before that it came out a single tube.
5. Lighting and duration - 8 hours photoperiod using the LED light that came with the tank.
6. Substrate - Fluval Stratum topped with decorative sand.
7. Co2 dosing or Non-dosing - No Co2
8. Drop Checker - N/A
9. Fertilizers used + Ratios - Originally I was using API Leaf Zone, but I wondered if this was causing a nutrient deficiency. Around 4 weeks ago I switched to a combination of NT Labs Plant Boost & Liquid CO2 Boost with two sprays of each per day. I haven't noticed any difference in plant growth or reduction in the brown leaves.
10. Water change regime and composition - I do a 20% water change each weekend. Most weeks I'll also do an extra 20% water change during the week, but not always.
11. Plant list + Invitro/Emersed - Salvinia, Rotala rotundifolia, Limnophila Sessiliflora, Anubias Nano, Java Fern + a couple of others that I can't remember the name of.
12. Inhabitants - 4 male guppies + around 20 red cherry shrimp

 

[sparkyweasel]

I think you need a complete fertiliser.

API are not very forthcoming with information, but Leaf Zone appears to be just potassium and iron.
NT Labs 'boast' that Plant Boost is free from nitrate and phosphate, which are two of the essential plant nutrients.

 

[_Maq_]

To my eyes it seems that the problem is restricted to Limnophila (while the others may look brownish due microbial mats).
Limnophila: Lack of light and possibly oxygen in the lower parts.
I don't think it's nutrition-related.

 

[alext8]

I think you need a complete fertiliser.

API are not very forthcoming with information, but Leaf Zone appears to be just potassium and iron.
NT Labs 'boast' that Plant Boost is free from nitrate and phosphate, which are two of the essential plant nutrients.

Thanks for the response. I just did a phosphate test and it looks pretty close to 0ppm. Nitrates are at around 10 and are pretty stable, so could phosphate be the issue? That would match up with the fertiliser I'm using not including phosphates.

To my eyes it seems that the problem is restricted to Limnophila (while the others may look brownish due microbial mats).
Limnophila: Lack of light and possibly oxygen in the lower parts.
I don't think it's nutrition-related.

Thanks. The photos don't show it very well, but the plants on the bottom left of 4.jpg (close ups in photos 2 and 5) have a similar issue - very green new leaves, brown older leaves. It's just a lot less noticeable because they grow slower and I didn't get a great photo of it.

Light could definitely be part of problem, although I've noticed that even when I trim the tops of the limnophilia so that some of the brown parts are in direct light, they still don't become any more green (although the new shoots are bright green).

 

[John q]

API are not very forthcoming with information, but Leaf Zone appears to be just potassium and iron.

Yep, potassium and iron.

Lack of light and possibly oxygen in the lower parts.

Not to sure its lack of light. I've had Limnophila grow in some of the darkest places and it remained green, the internode length would elongate quite a bit though, and looking at the op's pictures the internode length lower in the tank isn't a sign it's drastically bolting towards the light.

Lack of oxygen and or Co2, yes, totally agree with that, although I accept you may not agree with the latter. Either way @alext8 increasing circulation around the tank (not just surface agitation. That surfacewater needs pushing around the tank) will achieve both and think will bring improvements overall.

 

[_Maq_]

even when I trim the tops of the limnophilia so that some of the brown parts are in direct light, they still don't become any more green

Once a mature leaf takes any damage it will never recover.
The other plants (do I detect correctly some Ludwigia?) do have upper leaves greener than the lower ones, yes, but I seems to be quite normal state of affairs.

Once the plant finishes creating a new leaf, the job is done. After that, the leaf gets gradually worse, never better. From the plant's point of view, it's always a matter of economy. Mature leaves should require minimum maintenance and provide the plant with maximum benefit in the form of energy, i.e. sugars created through photosynthesis, and oxygen for respiration (= "burning" the sugars). If the leaf's budget is near zero, the plant lacks interest in investing in it. If it falls below zero, the plant sheds it. We can simplify the matter: as long as the old leaf gets enough carbon dioxide AND light AND oxygen, then it can photosynthesize enough to cover its own maintenance PLUS contribute to the plant. If any of the named three resources is in short supply, then the leaf bothers the plant with demands - either for sugars or for oxygen, or both. The plant will not accept it, it is likely to re-mobilize nutrients and amino-acids from such leaf and use them elsewhere. As a result, such leaves look ever worse, and in the end are shed.

 

[dw1305]

Hi all,

I think you need a complete fertiliser.

I'm <"sure you do">. Basically all plants need all of the <"fourteen essential nutrients for plant growth">.

You would be better with a <"complete fertiliser">, you can still <"add very small amounts">, it just adds all the <"nutrients plants need">.

You could use an <"aquarium fertiliser"> like <"TNC Complete"> etc. or a <"hydroponic"> fertiliser. Have a look at <"Solufeed 2:1:4 and Solufeed Sodium Free TEC or Solufeed Coir TEC Combination">.

(while the others may look brownish due microbial mats).

It might be diatoms. In which case it would rub off. It might possibly also be an oxidised ferric iron (Fe+++) compound in which case it might rub off, or it might not. If it is diatoms, they should feel <"gritty"> when you rub them between your fingers.

Lack of oxygen and or Co2, yes, totally agree with that, although I accept you may not agree with the latter.

Even the salvinia seems to be spreading much less rapidly - I haven't had to remove any for ages. When I first added it to the tank it seemed to multiply like crazy.

Neither gas would be my guess, mainly due to the <"lack of growth in the Salvinia">. Salvinia "auriculata group" will grow very chunky in high light (with enough nutrients). Access to atmospheric gases was one of the reasons for using a floating plant in the <"Duckweed Index"> - <"The scientific background to the "Leaf Colour Chart"">.


The only reason I don't recommend Salvinia spp. for the <"Duckweed Index"> is that they are hairy and that <"makes judging colour more difficult">.

cheers Darrel

 

[dw1305]

Hi all,

I just did a phosphate test and it looks pretty close to 0ppm. Nitrates are at around 10 and are pretty stable, so could phosphate be the issue? That would match up with the fertiliser I'm using not including phosphates.

They could, because you live in the SE of the UK you would be likely to have <"high levels of PO4--- in your tap water">, but you may have <"precipitated it all out with the iron (Fe)"> addition (from the "API leaf zone") - <"Iron phosphate">.

Personally I tend to make all my decisions about nutrient addition based on the health and colour of my floating plant. I have the potential <"to test for most ions">, but I've come to realise that plant health is <"a multifactorial question">, and that the <"plants can't lie">.

<"Watch the plants">, it works. A <"strange analogy"*>, but if you are football fan? It is like:

• You might think that your team is playing well every week, but at the end of the season they are relegated.

Your test kit results might tell you that things are fine, but if at the end of the "season" your "plant " is relegated? They weren't.

* <"Test reading not what i expected ?">

cheers Darrel

 

[_Maq_]

I just did a phosphate test and it looks pretty close to 0ppm.

It doesn't mean much. Phosphorus is an elusive element. I mean, it may be present in sufficient amount, and yet you measure zero phosphate in the water column.
On the other hand, this is what makes true phosphorus deficiency hard to detect, and when it occurs, it can be deadly.

It might be diatoms.

Sometimes I perform truly dark cycling of my tanks (meaning there's no light for algae) and such brownish mats often appear. I suppose it can be both bacteria or fungi. Anyway, it's a delicacy for snails.

Your test kit results might tell you that things are fine

There are always more killers than those we can detect with tests. When troubles happen, people often tend to seek for "a missing nutrient". In most instances, something else is at play.

But I do not insist that @alext8's case can't be an exception. I apologize for forgetting about your mention on the Salvinia. Like @dw1305 said, it truly indicates some nutrient deficiency, and it may well be phosphorus, indeed.

 

[dw1305]

Hi all,

Sometimes I perform truly dark cycling of my tanks (meaning there's no light for algae) and such brownish mats often appear. I suppose it can be both bacteria or fungi. Anyway, it's a delicacy for snails.

That sounds like it might be bacterial. If it isn't diatoms then I think the brownish colour must be because of ferric iron (Fe(III)), but after that I don't know. I'll try and ask a colleague.

cheers Darrel