What deficiency is this?

[R.K. Castillo]

I bunch of my leaves have a bunch of these discoloration spots.  You can see it best in the spot by my thumb in the picture.  What deficiency is this?

[Alex Veidel]

Hmmm, potassium maybe? If your leaf edges are dying/curling, it's potassium.

[R.K. Castillo]

If I use the KH tester...does that gage Potassium?  That might be a stupid question because it's testing Carbonate Hardness but is the K in KH referring to potassium?

[Alex Veidel]

You know, I don't believe it is. That's not a bad question though.

[Steve R]

its a little light green what is your nitrate levels at the moment? Have you added iron recently?

[R.K. Castillo]

I can add some iron to see what happens.  Nitrates seem a little low. 

[Steve R]

well if your nitrates are low i would start there. Then i would move on to iron. One thing at a time :)

[Casey Haas]

It's kind of hard to tell from the picture, but it looks like there might be some insect damage (maybe spider mites?). The mottling looks like what spider mites did to my snow pea plants. That's just a guess though. Check the underside of the leaves for webbing and/or little salt and pepper-like granules. You can only really see them using a loop or microscope.

Here is a handy key from Bright Agrotech for diagnosing deficiencies that might help you determine if it is a deficiency, what it might be, and some treatment options:

https://brightagrotech.leadpages.net/diagnosing-nutrient-deficienci...

KH tests do not indicate potassium levels in your system, but wouldn't it be nice if it were that easy? The only way I have seen to test potassium in aquariums is a fairly expensive test kit from Red Sea at $50.00 called Potassium Pro. Red Sea also has a magnesium test kit, Magnesium Pro for $37.00. They are fairly complex for a backyard setup though and I haven't wanted to pay that much for test kits yet, but if I do I'll let you know how it goes.

Good luck!

[Jeremiah Robinson]

I found this image about a year ago.  I've found it really helpful.

[R.K. Castillo]

According to that...then the problem is manganese.

How do you supplement that?

[Jeremiah Robinson]

Not a clue :)  

I'd start with Nitrates.  That's the most common problem.

[Jim Fisk]

Personally I just add a dollop of Maxicrop With Iron whenever strange colors appear and any strange colors that are not due to insects just go away. I get it right here at Sylvia's store. (Store tab above which at the moment is down or I would provide the direct link) Been doing that for 2 yrs now and it always seems to work and I believe strongly in supporting this forum.

[Vlad Jovanovic]

The "K" in KH actually stands for "carbonate"...as in "Karbonatharte", and has nothing to do with potassium. (Potassium is 'K' on the periodic table of the elements...because in most all other languages besides English, its called "Kalium"...or some derivative thereof, from the Latin Kalium. It got to be called 'potassium' in English after the common term "pot ash" since ashes contain mostly pot-ashium)...At any rate...

Measurements of KH have much more to do with Ca (calcium) since the two most common methods of expressing KH, dH (degrees of hardness) and mg/L (milligrams per liter...which is the same thing as ppm, parts per million), are expressed as mg/L of CaCO3 (calcium carbonate)...as if calcium carbonate were the only source of carbonate ions in the water...which isn't always the case...magnesium carbonate is also present in many water sources.

It's hard to tell from just that photo, but what you are seeing may not at all be nutrient related there...

R.K. Castillo said:

If I use the KH tester...does that gage Potassium?  That might be a stupid question because it's testing Carbonate Hardness but is the K in KH referring to potassium?