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I have a stand of about 15 mature Lobelia cardinalis 'Dwarf' that has gone through at least 4 melting episodes (stems, leaves, and roots turn transparent and literally melt) within the last year. Each and every time, K2SO4 was involved. I have suspected elevated levels of K to cause my L. cardinalis 'Dwarf' to melt, but couldn't conclusively say so since I dosed several things at once. However, yesterday, out of curiosity, I dosed some K2SO4. This morning, my entire stand of L. cardinalis 'Dwarf' has melted. :-x

I can't pinpoint a specific toxic K concentration because it seems to be a proportional relationship, relative to some OTHER nutrient(s) because the [K] that induced one melting one week, did not induce the same phenomenon in the next. I think Ca/Mg and/or N is at play here. Botany is not my forte, so I am hoping that someone on the board can propose a theory on why the melting occurred. Perhaps then, we can hypothesize the likely suspects: Ca/Mg, N, or some other nutrient is responsible.

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Other plants also melt but the L. cardinalis 'Dwarf' is the first to exhibit these symptoms. Once seen, the addition of more K2SO4 exacerbates the melting within the L. cardinalis 'Dwarf' and spreads to other plants: Pogostemon stellatus and Hygrophila corymbosa var augustifolia. Both plants did not exhibit stunting tips. Instead, the roots turn transparent, leaves detach at the node, and in severe cases, the stems turn transparent as well. Response time is relative quick: within 12-24 hours.

I would really really appreciate any insight.
 

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cS said:
I would really really appreciate any insight.
Don't add K2SO4.

If you are using KNO3 you are probably getting enough K. If youaren't seeing pinholes in the leaves of anubius or sword plants don't add the extra K.
 

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cS said:
yesterday.... I dosed some K2SO4.
I wonder what size tank and what quantity of K2SO4 you dosed?

What is the definition of an "overdose"? "dose too heavily; "The rock star overdosed and was found dead in his hotel room" " according to Princeton. Substitute plant for Rock Star - but, of course, in our obsessive hobby, plants are The Rock Stars ;-)

No comments to offer on the biochemistry involved. But I have seen Greg Watson write that he doses the same amount of K2SO4 as he does KNO3. Others seem to dose less. Personally, I found that KNO3 alone was not enough and that eventually growth stalled, presumably due to K shortage. It picked up again when I dosed K2SO4 (and thread algae disappeared too - that coming about as a result of dosing TMG). Judging by the way the plants literally fizzed moments after dosing, the plants must have been in a state of K starvation.... (no water change was involved to induce fizzing..)

However, I have been noticing that in my 20 tank the K2SO4 seems to "overdrive" the plants - at least that's the only way I can describe it. Growth is continuing (like forced rhubarb, if you've ever seen that pallid stuff some farmers sell) but leaf quality is nowhere as good as it used to be. Most likely, the overdrive effect is causing shortages of other components - I have to find a way of addressing that shortage.

In my 30, I also dose an equal amount of K2SO4 to KNO3 (dosing being on a daily basis) but I tend to test for NO3 daily (or eyeball the plants) and when NO3 uptake slows, I stop the K2SO4 dosing (but continue with a fairly high PO4 dose.) The leaf quality in the 30 is much better. The tank seems more stable as well. But to say that is inviting disaster, right ;-)

30 = Tonina, R. rotundifolia, Anubias sp., R. walichii, mosses, Eleocharis, Marsilea, L. Pantanal, Microsorium sp.

20 = Rotala sp green, L. aromatica var., H. callitrichoides, Anubias sp., Marsilea sp., H. pallustris, R. walichii.

Andrew Cribb
 

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Well, I experienced a L. cardinalis melt down recently, not due to K2SO4, but a few weeks after dosing an antibiotic(most plants showed deficiency and stunted but did not melt) which reacted with metals that redered most iron/trace unavailable. I was able to save a small piece of it and put it in another tank. I dose quite a bit of K2SO4 after each water change.
 
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