Re: melting Lobelia etc

[Thomas Barr <tcbiii at earthlink_net>]

> Just in the past few days, I've noticed the rotting of some of the upper
> leaves of my L. cardinalis, in the same manner described by B.C.; I thought
> the cause might be an "algae famine" in this tank and my Amano shrimp
> finally going after my plants.

They will not eat this plant. No algae eater seems too. Algae doesn't like
the plant either. 

> So I moved two of the three shrimp into
> another tank, but today, I was alarmed to see that many more leaves were
> getting transparent. Then I thought that maybe it was the snails - even
> now, they're scraping away at these leaves - but upon closer inspection, I
> see that the rotting appears to be originating from the stem. I'm not sure
> what to make of it. I've never had such a perplexing thing happen to this
> species. It seems to be happening to the tips of my pearlgrass (Amano
> variety), too!

Poor NO3. Moving it around too often, letting float, get overshadowed etc.
 
> Since June, I've been adding K2SO4 and Flourish Iron. I've been adding KNO3
> since last year with no problems. Also, about a week ago, I ran out of TMG
> and have been dosing with Flourish. I don't think this could cause
> leaf-rotting... In the past two weeks, I've added Hottonia palustris and
> Didiplis diandra. The H. palustris quickly died and was devoured by the
> shrimps and snails, but it was a very healthy cutting from a display tank
> at the LFS.

It (Hottonia) needs good doses of NO3. If you bottom out the NO3 for long,
this one will suffer. CO2 might be causing some slow down in growth also.

 Could the Didiplis diandra have harbored some disease that
> might have spread to the lobelias? I recently heard about a disease that's
> put a temporary stop to aquatic plant shipments from the Far East. Seeing
> as how B.C. is in Singapore and was experiencing this problem with his
> plants, my imagination is running wild... The last thing I'd want to do is
> to draw some far-fetched conclusion.

 This doesn't sound like this is the problem.

> So I'd like to first consider maybe
> K(+) or SO4(2-) overdose or sudden changes in fertilizer.

Unlikely. It would take _a lot_ of both to do anything.
 
> Maybe it's one of
> those things that "just happens" like Crypt melt, when you drastically
> change fertilizer regimen or add new plants... Or look at it the wrong way.

Well sometimes. But if you get the tank's nutrients in order with a water
change a good checking of the CO2 pruning etc this goes away or never
starts. Something's up if the leaves start melting. Do the basic maintenance
routine.

> Anybody want to take a stab at this? B.C., if you're reading this, did you
> finally get this problem under control? If so, how?

It's really a general thing. It's not some special "trick"  with only
certain special plants. A few seem to like more NO3 than others. Some need
PO4.  Once rooted, plants do better and can take more abuse in the water
column nutrient levels. But if you keep up on the water column nutrients,
you are well rewarded.
Just go down the line, 20-30ppm of CO2, then check the NO3 or else do a 50%
water change and add about 1/4 teaspoon of KNO3(and 1/4 teaspoon per 25gals
of K2SO4) per 25 gallons of tank water etc. Add 5mls of traces, wait a day
and add some KH2PO4( 2-4 rice grains). Add KNO3, traces, PO4 1-2x more
before your next weekly water change where you repeat this routine over a
gain. If you want to add some flourish iron in the middle that's fine.
Clean filters, add algae eaters back etc. Shrimps even at very densities
don't eat Lobelia and many other plants if the plants are growing well.
Regards, 
Tom Barr