Potassium Deficiency?

[Bartman]

I'm seeing small brown dots forming on the older leaves of my sword plants. The older leaves are getting up to 7 or 8 of these brown dots. The dots seem to be growing outward with time and the larger spots look like the plant is rotting.

I've read that this is a sign of a potassium deficiency.

Has anyone else had this experience?

Are the other potential causes for this?

 

[Tom Barr]

Look at CO2/NO3 frist.

Regards,
Tom Barr

 

[Bartman]

Well, I'm hoping my CO2 drop indicator shows up in the next day or two so I'm not sure of that level although I think its probably a little low. My new diffuser should be here in a few days as well so hopefully that will help on that front.

As for NO3, what's the best way to test the accuracy of the test kits? I'd rather not make 100 gallons of standard solution just to test the kit...

 

[Tom Barr]

I tend to think it is an old wives tale about holes in many plants due to low K+.
Sometimes, yes, it might be true, but I've seen much more evidence with CO2 and NO3 with holes and stunted growth.

If you have good growth and no stunting, and you have a few holes on the lower leaves, then perhaps.

I tend to redo everything and look over things in each area rather than chasing one nutrient.

You have a much higher success rate at fixing the issue this way.
You do not get a chance to isolate and study the deficiency is the trade off, which most folks don't really wanna do anyway.

So do a large water change,. dose things back, add a tad more KNO3, and tweak the CO2 a bit more **slowly**.

Regards,
Tom Barr

 

[Bartman]

Thanks Tom,

The growth has really started to pick up since I've switched to the EI method. Since I've got very little experience with good, algae-free growth I'm still trying to figure out what symptoms indicate as the problem.

It's confusing because everyone says something a little different, few have good pictures of what they're describing, and oh yeah it seems like they say EVERY deficiency has the SAME SYMPTOMS!

This time I saw something specific that was mentioned a few times so I thought I might have found the cause.

Either way, I'll just try to re-set the parameters a little after the water change.

Thanks.

 

[Tom Barr]

Now without any prior experience, and given what you see/read about on the web, that all the symtoms appear very similar, what are the odds out say 20 possible things it might be(could be more or less), that you will get lucky?

Not much.

Now if you use an EI approach, that rules out many things.
So you really are left with general maintenance and CO2, if you have enoghyb light and not too much and 10 hours per day, all that remains really is patience and CO2.

That makes my job and growing plants much easier.

It also allows me to isolate things very effectively, same with anyone that wants to delete say just PO4, or just NO3, or just Traces, or just K+(few folks do though, because few have non K+ based NO3 and PO4, although sodium based salts of NO3/PO4 and Ca(NO3)2 are easy to acquire to drive the K+ down.

So many never know unless they try to do it on purpose what K+ issues look like or not.

You also cannot use TMG, it has K+ in it also.
So what I am saying, if you add ferts, it's not likely you have K+ issues in most cases.

K2SO4
KNO3
KH2PO4
TMG

All add K+

Regards,
Tom Barr

 

[Frolicsome_Flora]

all that remains really is patience and CO2

I have the CO2, but whats this patience? I need to buy some of that!!

 

[Frolicsome_Flora]

Got the teardrop shaped drop checker today. Really pretty, but almost impossible to empty. Gotta use a LONG bit of clear silicon tubing to suck out the contents.

 

[Bartman]

Got the teardrop shaped drop checker today. Really pretty, but almost impossible to empty. Gotta use a LONG bit of clear silicon tubing to suck out the contents.

Yeah, I thought of that when I was looking at it. Luckily, I have a very skinny eye dropper. It came in a bottle of liquid ferts or something. I forget which one now, it may have been a smaller bottle of Excel or maybe a bottle of Cycle. It's graduated every ml from 1 to 5 ml which makes the tip end of it pretty skinny so it should fit in there nicely.

I'm pretty clumsy so I figured the skinny neck in there would help to keep me from dumping the contents into my tank...

 

[Tom Barr]

A cheap 50 cent plastic pipette works great to remove the liquid, you may also rinse out with the KH ref solution.


Regards,
Tom Barr