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Discussion Starter #1
I came across this in a plant (Barclaya longifolia) description:

Special note: Reacts immediately to high Redox- respectively Oxygen values with holes in the leaves.

I've been trying to figure out why my red tiger lotus gets holes in its leaves. It's not potassium deficiency - have plenty of that. All the other plants in the tank are fine.

I am terrible with chemistry and don't know anything about redox etc. etc.
Could someone possibly explain this to me? :eek5:
 

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oxidation reduction potential (redox or ORP) the waters ability to reduce organics thru oxidation. Usually a common term in reeftanks, Usually when using ozone o3 . I dont think this is your problem. It sounds more like a nutrient defeciancy. I suppose the ORP could be high in a freshwater tank but never measured.
 

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Do you have snails or a pleco? I had the same problem with my red lotus, then removed both of these and things got much better. Not completely, though. The lotus still tends to occasionally get melting/holes, especially on older leaves. It looks like some sort of defiency to me and I was considering K as a problem since I've been dosing it very lightly. Maybe not. Still working on this.

With regard to redox, redox basically measures the pollution/decaying matter in your tank. The higher the redox, the cleaner the water. Think sunlight - the brighter the better. I'm not sure about the quote you saw. I found it online as well, and it's not exacly clear what it means. Sounds like they're trying to say it's bad for the Barlaya if the redox is too high. I guess it's possible, because redox can be overdone, but usually this is when chemicals are used (eg KMnO4). I've never read about it being too high in any natural sense. Anyway, I've improved the redox of my tank a lot lately, and the red lotus holes were worse when the redox was lower - and the snails and pleco were present :) . I doubt redox matters.
 

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Discussion Starter #4
Too much potassium?

Thanks for the responses. Yes, that Barclaya description is confusing- had no idea what it meant. But I did find a site that explained the redox thing pretty simply so I learned something new :)

As for the holes in the lotus, still don't know what those are from. I have no plecos. I do have pond snails but they are controlled by the clown loaches and I've never seen them on the lotus, nor chew holes in anything else. I would suspect the loaches but the holes look more the way wapfish described them - like melted or burnt. I can't imagine it being a deficiency - I dose regularly and monitor frequently with test kits, as the tank has only been up for 2 months and I'm still tweaking the ferts a bit. I have also taken some steps to improve the redox over the last couple of weeks - without knowing what it was :icon_wink - so maybe the holes will disappear??

I was also wondering if too much potassium in the water would cause any problems. I like test kits so out of curiosity I bought a potassium kit and found my tank was real high. I thought the test was faulty so I tested my tap. Not as high as the tank that I had been dosing with potassium, but still much higher than the recommended 2ppm. Still thinking there might be a problem with the test kit, I tested some rain water from outside, and it was clear of potassium. Anyway. I'm not dosing that anymore, and will be watching to see what happens next :)
 

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acwitness said:
I was also wondering if too much potassium in the water would cause any problems. I like test kits so out of curiosity I bought a potassium kit and found my tank was real high. I thought the test was faulty so I tested my tap. Not as high as the tank that I had been dosing with potassium, but still much higher than the recommended 2ppm. Still thinking there might be a problem with the test kit, I tested some rain water from outside, and it was clear of potassium. Anyway. I'm not dosing that anymore, and will be watching to see what happens next :)
Hmmm. I like test kits too and just bought a potassium kit. It's not here yet.

Guess I haven't done my homework adequately. Where did you get the 2ppm recommendation?

I wonder to what extent optimum K might be dependent on hardness/Ca/Mg also. My understanding of the prevailing general wisdom is that the K requirement has rather a broad optima, with much higher K levels (up to 50ppm ?) being pretty much OK, and with not much being required to prevent deficiencies. That being said, however, I've definitely run across threads where folks reported substantial improvements by raising K higher than "normal". One of those tank-to-tank things?

Anyway, I've been increasing my K recently, the opposite direction from you. Too early to say if there's any difference. Need the test also.
 

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Discussion Starter #6
Hi wapfish - I got the 2 ppm from the test kit instructions, but I, too, have read about the higher levels of K being ok, or even beneficial. My only minor concern with the high level in my tank is my soft water. GH and KH are both 3. I've read that high levels can cause calcium deficiency in soft water, but I don't know how soft the water, or how high the K level would have to be to cause a problem. Anyway, I figured since the K is so high, I would just try not adding anymore for a while and see what happens - no sense in continuing to dose something if I don't need it. Everything in the tank is doing well at this point, and there is no algae. But then I can't seem to grow easy things like java moss, java fern, or pellia, even though my tank conditions would seem favorable for them :icon_roll
 
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