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Re: MG and PO4 and other stuff

> Tom Barr said:
>> I do not think [Delaware Aquatic Plant Tabs] have NO3/NH4 or PO4.
> When I had them tested many moons ago, I found they had N and P... dont
> know what form. But you covered all the options above.

Yea guess so. I never used them in the water column and never tested them
for any of that but looks like they do got the N and P.

>> So was it the NH4 and urea or the PO4 that helps your plants? Urea can be
>> quickly converted in the presence of water and oxygen and bacteria into NH4
>> and used.
> GOOD QUESTION. I did not even notice that half of the N is from ammonium
> phosphate. At least the NH4 concentration is only ~0.05ppm... which my
> article on the KRIB says should be safe.

Oh yea, at that concentration things are fine. But NO3 effect and NO3
effects on plant growth are different depending on the species need for a
NO3/NH4 ratio.
I think this is a good product and idea for those tanks that are a tad poor
on the NH4 side of things.

>> So how much NH4 vs PO4 is there here? Try a .5ppm level of PO4 and a .4ppm
>> NH4. 
> While 0.4ppm NH4 is not supposed to be lethal, it is uncomfortably high for
> me. 

Yea, I think .1ppm or less seems fine. I'd rather keep it darn low.
How much NH4 is coming in from the critters though? If we add NH4 and feed
fish what are the plant's needs relative to a set level of NH4 to drive
maximum production? I really want to play with this idea but..........
I still feel that I can do what ever I need to do with planted tank without
resorting to any of this and using KNO3.

But going to back to this again, planted tanks with a nice fish load always
seem to do better than tanks where I add only KNO3. It may be due to
herbivory but I also tried it with snails and the snail only tank did not
have the same vigor even with plague density levels of snails. Adding fish
food to rot was the next step never took that one though. Didn't someone do
that already(fish food as a plant fertilizer)? I know I've seen at least a
couple of those and it did alright but did it say what % was NH4 vs NO3?

> At pH 7 and 86deg, 1-hr concentrations should be < 12ppm and 4-day avg
> value less than 0.7ppm. The plants should suck up the NH4 quickly and not
> permit a long-term value to be close to 0.7. Nevertheless, I'll let you do
> that experiment.

Not with fish:-) Unless I do not like them. Sacrificed for science:)

Snip <generalized Tom bather>

> I am not sure I understood what you said, but please report back when you
> have a more complete assessment.

Just that the algae can use the organic PO4 and the plant cannot or can only
use it to a much lesser degree. This may only occur in the water column.
In the soil I am pretty sure that plants have this enzyme in the roots.
Floating plants like Riccia? Not sure.
> Maybe urea is like time released ammonium.

It is generally though of this way in terrestrial systems(your potatoes,corn
etc). In aquatic systems it appear to converted fairly quickly. It's a by
product of a few processes and is therefore cheap.

> This might be a great source of
> N in a heavily planted tank.... and might prove to be reasonably safe at
> concentrations of up to a few ppm

I think it's safe to assume it will turn into NH4 fast. Maybe algae and
plants do not have any advantage for this one(I'll pick this side) but maybe
they do.

>> Is using one species as a ruler good for all plants?
> I have to agree that one species is not the ideal ruler. But this was the
> only critical concentration data that I had (from Diana's book). If anyone
> has other quantitative info, it would be great to have.

I have some but not too much from aquatic, namely terrestials. The usage and
needs are quite variable in their relative %'s. I am applying at U of F for
their water science grad program so I'm seeing who's doing what at the
aquatic weed research facility. There's even cave algae that can grow in
moonlight intensity.
> It would be very helpful for you to document and publicize those plants
> that "seem" to require different relative amounts of PO4. We all thrive on
> such anecdotal evidence.

Yea, I still have a lot in my head but I want to get some good controlled
designs going in case I have overlooked things. That aspect always bugs me.
I'm certain of a few plants. Guesses for others, generalizations for most
plant groups. 

>> Depends on what species of N. It does add enough NH4 for the tank.
> Are you suggesting that the MG provides enough NH4?

Yes, good for that and some PO4 in limited or "lean" tanks.

  If so, the tank would
> still be lacking in N, absent other sources.

Yea. But it'd still be better than nothing or if you had to "get by" for a
week or so.
> Why bother with ammonium sulfate. Why not use liquid ammonia (from grocery
> store). I believe it becomes NH4+ at pH in our tanks. Chemists, please
> comment.

I could use that I guess. I just like dry powders:) I have a 25lb bag
sitting here with nothing to do. I think the NH3(l) would work better
>>MG= algae if the NH4 is too high:

> I agree. The one time I experimented with adding NH4 to my tanks, I quickly
> produced green water.

I think it's certainly safe to say that NH4 in high enough levels will cause
GW almost every time. I want to see and isolate NH4 though and make sure
it's not a combo of P04, Fe etc that causes it. I think NH4 is the lion's
share for inducement to occur for GW and I'd bet at least one maybe two more
common pest algae(staghorn-Entromorpha sp comes to mind also).
Tom Barr