plantnoobdude
Member
I saw people dosing 50 plus's ppm K and had pinholes while some people were dosing tropica and had perfect pinnatafida. Clearly the issue is outside this factor.
-
You are viewing the forum as a Guest, please login (you can use your Facebook, Twitter, Google or Microsoft account to login) or register using this link: Log in or Sign Up
Targeting Potassium
- Thread starter hypnogogia
- Start date
I missed this. In a previous discussion I had some advice that the ration of Fe to Mn was off in my micros and tnag I should add more Mn. I haven’t yet ordered any, but will do so to see if that addresses the pin holes.
It's always good to experiment and find out. In some of those pictures I posted earlier, I have gone beyond 3 ppm N using Urea or NH4.
If I understood you correctly, the photos in C and D show the symptoms of excess potassium, right?
I see white top leaves with still green veins. Would you say that is an accurate description of the effects of excess potassium?
The potassium concentration was 15.6 ppm for these tanks. Is the concentration here important, or is the biggest issue that K:Mg for C and D was 4:1 by weight (way higher than for A tank - K:Mg 1:3)?
_Maq_
Member
Not really. What you see is magnesium deficiency caused by excess potassium. Excess potassium hinders Mg & Ca uptake even if Mg & Ca are present in sufficient amount. That's the point. (And I didn't invent it, this is a scientific fact.)
Similarly, you can possibly detect (it's poorly visible on pics) Alternanthera leaves wrinkled in tanks C and D. That's a sign of calcium deficiency, again induced by excess potassium.
I believe that ratios are more important than concentrations. However, I run most experiments (and "normal" tanks, as well) in rather soft, low-mineralized water. That's because my focus is aquatic plants, and most of them require or prefer soft acidic water. Due to that I can't really swear that my ratios are still valid if all components are multiplied several times.
I see, thanks for the clarification on the description of the photos. Let me rephrase then
The white top leaves with green veins in Hygrophila corymbosa from C and D tanks show magnesium deficiency symptoms as a result of hindered magnesium uptake from a K:Mg ratio of 4:1 by weight (respectively 15.6 ppm K and 3.9 ppm Mg available). Is this a fair description of your conclusion?
The white top leaves with green veins in Hygrophila corymbosa from C and D tanks show magnesium deficiency symptoms as a result of hindered magnesium uptake from a K:Mg ratio of 4:1 by weight (respectively 15.6 ppm K and 3.9 ppm Mg available). Is this a fair description of your conclusion?
Last edited:
Oldguy
Member
This true for terrestrial plants, but is it true for aquatics? These plants are very leaky and potassium is not bound in the plant so it can enter or leave.
_Maq_
Member
Just look at post # 29 and you'll see.
Oldguy
Member
Remind me what is post #29.
_Maq_
Member
This is post # 50, as you can see in upper right corner.
I think he means the photo of the H. Corymbosa showing Mg deficiency.
The transport systems of aquatic and terrestial plants seems largely the same - exceptions include no dedicated Ca2+ inward ion channel discovered for aquatic plants (yet) - which suggests that Ca2+ and K+ compete with Mg2+ for the use of the Non-selective cationic channels?
For reference, I am dosing 4.2ppm of K weekly through a mix of Tropica + APT, which is not lean, but certainly not EI either. More significantly, I have reduced my dosing. I take a photo of my tank after every water change, and I would unscientifically say that my A.Pedicatella look happier (or less terrible) with reduced dosing (though admittedly the other thing I changed was to move to fortnightly water change so that may have contributed). I am happy to learn from someone who grows A.Pedicatella in EI, but they aren't keeping a journal in UKAPS.. someone needs to invite them to set up a journal 🙂
Last edited:
MichaelJ
Member
While I do find the experiment conducted by @_Maq_ convincing to the point where I am in the process of changing my K:Mg:Ca ratios to what is suggested by his experiment to be closer to ideal, I must say that I have been pretty happy with my plants at very excessive levels of Potassium. Back in 2021, before switching to 100% RO, I would mix in Tap water 50/50 from our KCl resin based household water softener getting me a staggering 80-100 ppm of K with each water change. I believe at that time I was targeting around 10 ppm of Mg, 30 ppm of Ca. And when switching to 100% RO, I was using Seachem equilibrium for a while which gave me 70 ppm of K for my 30 Ca 10 Mg target. Still, I was pretty happy with my plants. Eventually I went with dry salts and ended up with far less K - closer to my Mg level but still a bit higher. If I had to take the stand on this, I would not be able to honestly say that my plants did significantly better with the much lower levels of K compared to the super excessive levels. But I am very curious to see how it will play out in my lean tank now that I am really low on K vs Mg - which is a first for me.
Cheers,
Michael
Last edited:
_Maq_
Member
Excuse me, but it's a very simplistic position. I believe you've got it from an old post by @ceg4048 . Most of the potassium within a plant is in ionic form, in solutions, that's true. But majority of K is inside the plant's cells, even in organelles and vacuoles. Do you think that ANY ion can get there or out by a mere diffusion?
Of course not. From vacuole to outer environment, any ion must pass multiple "checkpoints" - membranes, guarded by specific proteins, through which the transport is controlled, mostly electro-chemically, actively, and as such, requiring energy input. It truly makes little difference if behind the last checkpoint there is an air or water.
The plants as such are NOT very leaky, and in most cases, they must spend energy when they want to get something in or out. They could not survive if they were "leaky" and depended on mere concentration gradient, that's a nonsense.
I hadn‘t, mainly because all plants, including those close to the substrate are gently moving in the flow, and plants are also pearling. I also thought that CO2 deficiency manifest in new leaves, not old. Where can read more?
.... Every time I look at Sudipta's low-tech tanks I realize how abysmal I am at this
Can’t see any mention of pin holes in that thread.
That was the whole point.
