Re: PMMD observations

>From: fidder at bighorn_dr.att.com
>Date: Fri, 7 Jun 1996 11:16:22 -0600
>Subject: PMDD observations
>I have been experimenting with PMDD mixtures on my 180 show tank 


>I have currently been using supplies from the local garden shops so the
>mixture I have been playing with looks like: 
>	* 2 tbs cleated iron miture (11%)
>	* 1 tbs mg (epsom salts)
>	* 2 tbs potash (K20)
>	* 1 tbs Ammonium Sulfate
>	* 250ml water -- I use the old $90 dupla drops bottle :-)
>I add about 20 drops every morning to the 180. 
>WOW! What a difference it has made. The first week the plants exploded.

I bet the plants liked the ammonium sulfate!! But the fish probably didn't!!

>The real suprise was that after two weeks of this, the thread and hair 
>algae has completely gone! After a 1-1/2 years this is a first.
>Some observations:
>	2. After using the mixture my phosphates went to 0.5ppm or higher
>	   very curious since I was careful to only add non-PO4 based 
>	   components. I did some testing and think that it is coming 
>	   from the Ammonium Sulfate. FYI: I also tested positive P04 
>	   from Flourish.
>	3. When the algae disappeared my phosphates were reading 0.3ppm.
>	   So much for the phosphate <==> algae relationship. 

Algae also need all the same elements that feed plants. With faster growth,
the plants are pulling nutrients out of the water and storing some for
future growth. The water could have run out of something else (besides P)
which the plants have stored and are now recycling for their own continued
growth (e.g. N,P,K, Mg, Zn), while the algae are starving.

>	5. The Ammonium Sulfate does cause a small increase of nitrates;
>	   however, it is short lived (5 hours later I didn't get a reading).

I would be more interested in learning what the hourly ammonia
concentrations were.(I always wanted to do this experiment!!) Also, what was
your pH and types of fish present. If you were adding as much NH4 as I
think, your results are interesting. I added NH4 once and stopped when I
started loosing fish... at the time I was injecting CO2, but did not have pH
controller and the pH was ~6.8-7.2.

Unless your pH was very low to cause the % toxic NH3 to be low (e.g. 0.1-.2%
@pH=6.5) and/or your plants were sucking out the ammonia very quickly, you
could have seen some mortality due to short term (1-hr) or longer-term
concentrations (see below). THis is an advantage for a pH controller to keep
any lingering NH4 non-toxic. It would be nice to know who quickly the NH4
lingers with actively growing plants.

pH      duration         Lethal* Ammonia Concentration (ppm)

                         total   NH3

6.5     1-hr             14.3    0.036
        4-day             0.73   0.002

7.0     1-hr             11.6    0.093
        4-day             0.74   0.006

7.5     1-hr              7.3    0.181
        4-day             0.74   0.019

>	6. Maybe unrealted, but I did add flourish tabs to the substrate
>	   about two weeks ago; however, my notes indicate that the plants
>	   had already shown marked improvement. 
>I have run this for about 3 weeks, which is too short to draw conclusions,
>but I like what I have seen so far. I will probably still use a combination
>of Flourish and my local mix since I don't have a full micro-nutrient mix.

This strongly suggests that Flourish may contain PO4, and that it slowly
leaches out. Within the 3-week test, many things could be happening.
Further investigation of the flourish is warranted.


Neil Frank, TAG editor    Aquatic Gardeners Association    Raleigh, NC USA