Is this a MG def problem?

[drumin]

Well? :D

[Shadows]

it does appear so from here.

[gorilla]

that's what it looks like to me, drumin. i compared it to a thread on ICMag called the complete guide to sick plants. you can find it here icmag.com/ic/showthread.php?t=11688&highlight=complete+guide+sick+plants . This link is worth it to post. :o

Seems as if you caught it pretty quickly. I'd give it some epsom salts anyway because it might work, and as long as you're not too heavy handed it won't cause any damage anyway.

[CB]

same..... looks like the start of -mg :)

[drumin]

Thanks guys, that's what I thought it was from looking at pics in the OG FAQ but I wanted to verify. Fortunately I happen to have some CAL-MAG handy. ;)

Any idea how this could happen to clones that are only about 1 week old (after sprouting roots of course). I used peat pellets to root them and then straight into FF soil and a little FF Grow Big. :shrug:

[gorilla]

I'm not sure exactly how it happens, Drumin. but, I would continue to feed with epsom or cal/mag until the problem is fixed for sure. Obviously there is something in the dirt the plants are not liking when regarding mag. Don't be afraid to supplement.

[WilliamClarkeQuantrill]

too high a pH is usually blamed for -mg, but too much k or ca can also cause uptake problems.

[drumin]

So there I was looking at my poor plants which are drooping, clawing and purple stemmed with turned up edges and taco shaped... all the classic signs of cal and mg problems. I've been wrestling with my PH meter and a new bottle of aquarium PH test liquid. I decided to call Milwaukee Instruments and ask about their meter. Turns out that my RO water is so clean (7ppm) that it's absorbing carbonic acid which causes the meter to slowly drop to the correct reading (around 5.6ph). Long story short, I need to give the water a couple minutes between each adjustment and additive, so when I add PH up, that needs to sit a couple minutes before I test again or add nutrients. I guess I've been locking up nutes due to PH swing.

Hopefully I can clear this up now that I understand what's going on. I've been having this problem for quite a while now but it always seems to clear up after the plants got bigger. I think because they get transplanted which helps. We'll see.

The guy at Milwaukee Instruments was really knowledgable and helpful in figuring this out. He said he's only seen this with distilled water because there is no salts at all to buffer the carbonic acid. Because my RO water is below 10ppm it's acting like distilled water and absorbing the carbonic acid from the atmosphere, making the water acidic.

[CB]

I tried RO water once in a bubbler but had a heck of time ph'n it.... hope this sorts the issue out for you drumin, and thanks for the tip on RO ppm and how it works with ph pens :)

peace