Frogbit web pattern damage

[RickyV]

Hi all,
My frogbit i use in my duckweed index container for my tank has been having this problem the past few months. It has these dry/burnt looking web patterns growing on it. As you can see the red root floaters growing right next to it are growing just fine with no problems. I may be wrong but I feel like i started having these problems after upgrading to 5 netlea AT6 pro lights. Is it possible the lights could be damaging the frogbit? I didn't think this was possible as it grows just fine outside in full sun, but I don't know what nutrient deficiency could be causing this. My frogbit growing outdoors in full sun with no fertilization in hard water is growing just fine unlike this one in soft water with plenty of fertilization. Dosing is
15 ppm K per week
3 ppm PO4 per week
0.20 ppm Fe edta from CSM+B total per week (split into 7 doses)
0.20 ppm Fe Gluconate total per week (split into 7 doses)
0.15 ppm Fe DTPA total per week (split into 7 doses)
5 ppm Mg per week
20-30 ppm Ca in water column
KH 2-3
degassed pH: 7.5
WC: 50% once a week with RO
I dont dose NO3 atm but the fish stocking is heavy and the tank is fed a lot of food. The red root floaters indicate there is plenty of nitrogen.


At times it has looked better, but even then you can see a subtle amount of the web patterns.
This is where the frogbit grow, the container has no problems with condensation, surface agitation or snail damage. Looking at old pictures I've never had anything like this before having the netlea AT6 pro lights despite a lot of experimentation with dosing (previous lights fluval plant 3.0). But like I said they have looked better at times so it may be related to some nutrient that the frogbit is demanding a lot of because of the light. Or a nutrient that helps it protect itself from the light? It's weird the red root floaters seem to have no problems.
@dw1305 do you know what this could be?

 

[G H Nelson]

Hi
Some of the Duckweed looks pale!
I would add Nitrogen fertilizer.

 

[Miniandy]

The Frogbit looks old, have you been removing the new growth? I've noticed that older plants go weird over time and more recently I've been removing the older plants and leaving only the newer ones.

I've also had issues with it growing in my older aquarium, presumably a nutrient deficiency of some kind. I always suspected iron and found some positive results when dosing iron and potassium.

 

[keef321]

I get this pattern with nutrient deficiency, normally iron or manganese for me. As you say they take full sun ok, that rules out lighting I would think.

I see you are already adding iron, but you can always add a bit more to see what happens. I notice your KH is at a good level, but your PH looks higher than I would expect for this KH level. Do you know what your general hardness GH is?

 

[dw1305]

Hi all,

I get this pattern with nutrient deficiency, normally iron or manganese for me.

I think it is probably an <"iron (Fe) deficiency"> issue as well. I've recommended <"Chempak Sequestered Iron"> to UK members, because it also contains manganese (Mn) and magnesium (Mg), so it covers all bases.

This is also iron deficiency, just at a stage where the iron supply has been turned off during leaf formation. These <"netted, reticulated">, <"striped"> or <"snake-bite"> lesions are how iron deficiency looks in a monocotyledon, the different appearances being dependent on leaf shape.

Image from <"Frogbit taken a turn">.

0.20 ppm Fe edta from CSM+B total per week (split into 7 doses)
0.20 ppm Fe Gluconate total per week (split into 7 doses)

I might try another chelator? One that is better at <"higher pH levels">.

cheers Darrel

 

[Maf 2500]

If there is enough nitrogen going into the tank from fish waste to not need to dose any, there is likely enough phosphate entering the tank the same way. It might be worth cutting down on the weekly PO4 additions and see if it improves the situation with the iron availability.

 

[RickyV]

Thanks everyone, it does look like it is iron/manganese related. I was looking at the date for the picture where the frogbit looked a bit better and found the micros recipe I was using around that time. It was the following below.
0.20 ppm Fe EDTA from CSM+B total per week
0.07 ppm Fe DTPA total per week
0.20 ppm Fe Gluconate total per week
Hmm it seems doubling the DTPA made the web patterns worse. I remember increasing the DTPA to my current dose to fix the previous web patterns but it may have made it worse. Though I might have raised my PO4 also around this time, so it could also be this. Unfortunately I did not keep good records of this. I will have to experiment and post back with an update on the results.

 

[Teleos]

View attachment 225722
View attachment 225723

To me, this looks more like toxicity than a nutrient deficiency. Maybe too much Mn. Or any other micro nutrient.

 

[RickyV]

I removed the DTPA iron and gluconate and kept only the 0.20 ppm iron EDTA from CSM+B and the frogtbit is looking much better. I'm thinking that since I added aquasoil recently it softened the water enough that the availability of the DTPA and gluconate iron increased to the point that it was competing with Mn for uptake. Thoughts on this? Though the frogbit looks better I don't believe it is perfect. You can see the duckweed next to it has quite a few pale new leaves. If Mn was the issue then perhaps adding some additional Mn may help?

 

[Teleos]

If Mn was the issue then perhaps adding some additional Mn may help?

The Fe : Mn ratio of CSM+B is about 4:1. A little more additional Mn could help. You have to try it out. I use a FeDTPA : MnEDTA ratio of 3:1 (kH about 4 to 5), so I have no problems with this. The Duckweed shows you first whether it works.

 

[RickyV]

Maybe I spoke too soon because another week later the same patterns are appearing. Though i think the plant is still improved as before it was barely growing at all. So since it is appearing on oldest leaves does this mean it is a macro nutrient? Or is it possible for a micro nutrient to do this, and what I am seeing is the damage after time has passed? Waiting on my Mn to arrive in case that is the problem.

Here are RRF