the plants are speaking.. what're they're saying?

[Peekay]

Hi guys.
Went away and didn't leave adequate details.... shoot.
No excel for a week, and I believe they overrode the timer on the lights, because the tank was covered in algae when I got home.  I also use flourish comprehensive weekly, but this I did just before leaving and did again on return.

A lot of plants have gone off colour... you can see it in my build thread, the pathetic blyxa is the colour I mean.  And the rotala green, well.. it isn't.    All the ludwigias have this leaf thing pictured... clearest in the leaf facing us half way down, where the edges all around the leaf are pale brown.  

What's this guy telling me that I don't understand?



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[exv152]

The browning edges could be Molybdenum deficiency. Check it out here...http://www.theplantedtank.co.uk/deficiencies.htm

[Peekay]

Thanks Eric.  That's a bit obscure!   

Maybe this then?  Potassium?

Molybdenum (mobile)
Mo ≯ 0.01ppm
DC Tap water 0.001ppm
✒ BAR - Boron and Molybdenum
Most molybdenum in plants is concentrated in the enzyme nitrate reductase, essential to inorganic nitrogen assimilation (Reduces NO3 to NO2 and then quickly to NH4 for assimilation into amino acid production) occurring in the envelope of chloroplasts in leaves. As such, deficiency symptoms are very similar to those for nitrogen and potassium deficiency. Molybdenum may also play a part in iron absorption and translocation in plants and increase antioxidant function. Molybdenum deficiencies are rare, in most cases. However, excessive dietary intake of molybdenum results in copper deficiency in some animals.

Potassium (very mobile)
K+ ≮ 5ppm
DC Tap water ~3ppm
K2SO4
Plants can not use phosphate or nitrate when they don't have potassium available.

[daworldisblack]

Not sure if you seen this yet but this thread may be helpful : http://ovas.ca/forum/index.php?topic=35078.0

[Peekay]

Thanks Rah, yep I'd gone through that... about half the links are dead.   

[exv152]

Molybdenum is a micro nutrient available in http://www.seachem.com/Products/product_pages/Flourish.html at a concentration of 0.0009% which should be enough for you. Chances are you also have some other deficiencies to boot. Flourish is probably your best bet to replenish all those obscure micros and it's commonly available, and you ideally want to have a bit more than the plants require.