Phosphate Diffusion and The Apprentice Sorcerer

Subject: phosphate diffusion from substrate

Steven Pushak wrote:
> I did the test on both aquariums and found both to have about 
> 1ppm of total phosphates, perhaps a little less 


> Both of these aquariums have
> plant stix fertilizer pushed as deeply into the substrate as I
> can manage and in place for a couple of months. There doesn't 
> _seem_ to be a problem in my tanks with phosphate diffusion
> or leaching from the substrate. I use Salvinia; perhaps it coul
> reduce phosphate concentrations somewhat... I also fertilize
> twice weekly with Flourish so perhaps the Fe helps precipitate
> excess phosphates too.

I would consider 1 ppm phosphate to be too high.  I have had algae 
problems with phosphate reading over .5ppm, and prefer to have 
readings unmeasurable with standard test kits.  
> One problem with some fertilizer tablets might be that they
> dissolve or become soft almost immediately upon getting wet. Whe
> one pushes them into the substrate, a fair bit of the soft part
> could break off and mix into the water or the surface of the
> substrate. Something to think about.  I wonder if that could 
> have been a problem with the DAI tablets Karen?

They seem pretty solid, but it certainly is a possibility.  If 
this were the _only_ way the phosphate made it into the water 
column though, you would expect that the amount could be greatly 
reduced by a few large water changes.  That was not the case.  The 
phosphate level stayed elevated despite MANY large water changes 
for a good 6 weeks.

> A wise precaution
> is probably to put any fertilizer tablets into the substrate
> only during the tank set-up until it's absolutely necessary to a
> more if/when there appears to be a shortage of nutrients. Anothe
> precaution is probably several large water changes every few
> days if phosphates test high after adding substrate tablets or
> sticks. I will surely check if or when I add any more. As some
> folks have said, it's probably unnecessary to add nitrate or
> phosphate fertilizer if the tank is well populated with fish
> and you are feeding regularly. The ones I added appear to have
> made little difference but it's so subjective. 

That would tend to make me think that phosphate/nitrate were not 
the limiting factors in your tank.  Otherwise you should have seen 
a pretty immediate increase in growth.


Subject: Apprentice Sorcerer's Recipe for Failure (ASRFF)

> I agree on your point of not jumping to conclusions about the ef
> medications on plants. I used the formaline more than a month ag
> Fluke-Tabs was first used less than a week ago. Would you consid
> acceptable to say that they did not appear to cause and immediat
> damage (like some algae controllers can do)? In terms of late ef
> formaline seems OK in my tank conditions, while for the other th
> unknown. I do not know about their potential effects in differen
> conditions or on different plants, nor about more subtle problem
> have created. 

I do not know for sure whether the products you have used 
will/have damaged your plants or not.  This is a standard 
disclaimer to all who use medications in planted tanks.  I was 
just warning you to keep your eyes open for trouble down the line, 
and remember that you used these medications _if_ they occur.

> I was thinking that probably negative effects on plants can occu
> (when the medication targets negatively a certain physiologic fu
> the plant) or indirectly (when the medication does not do anythi
> plant itself but affects other organisms or chemical parameters 
> plant needs). For example, from some gardening magazines I under
> certain nematodes are beneficial to plants, since they kill some
> root parasites. An antibiotic active on nematodes could indirect
> more plant parasite problems (this is a simplified example of co
> So, I am worried probably as much as you are about them, but I d
> the risk was worth the potential benefit. This is of course subj

IMO, it is better to avoid illnesses in planted tanks.  I _nver_ 
add medications to my planted tanks.  I quarantine new fish, and 
in the rarte instance that a fish _does_ become ill, it is removed 
from the tank if medication is warranted.  The introduction of 
most diseases can be avoided with forethought.
> I know PH Down contains phosphates. However, the 1 ml I added is
> the volume of the 300ml batch of PMDD I prepared. Would you agre
> is a negligible contribution to the phosphates content of my tan

I think that adding _any_ phosphate to a planted tank containing 
fish is too much.

> know of a truly phosphate-free pH decreaser, please let me know.

Muriatic (hydrochloric) acid. 

> I did not understand you comment on the leaching of phosphates V
> the substrate. 

You commented that you thought that keeping the phosphate rich 
plant tabs deep in the substrate would prevent the phosphate from 
entering the water column.  Later you wrote that you thought that 
iron _was_ leaching from your substrate.  I'm no chemist, but I 
don't understand why you think one would and the other wouldn't.  

For that matter, I believe that the iron in laterite is in a form 
that is not available to plants _except_ in the reducing 
environment of the substrate.  

> Do you mean that in my tank the DAI tables in the
> contribute to the phosphate levels? If so, I certainly agree wit
> However, do you think that in a tank without my problems the DAI
> should not be used anyway? 

Yes and yes.  I would not use DAI plant tabs in any planted tank 
that contained fish and/or was brightly lit.

>Could different substrates and tank c
> procedures affect the rate chemicals leach in the water from the

That is certainly a possibility if not a probability.  
> Thanks for the tip on the tank diagnostic form. I will look at i
> I disagree with your feeling that I am the most likely cause (or
> contributor) of the problems, though!

That is not what I meant to convey.  I think (am fairly certain) 
that you had some major problems in your tank _before_ using PMDD.

> There are several reasons. Amongst them, consider that the disea
> started before I found the PMDD recipe, it did not get worse aft
> using them, and that most of the fish in the tank just look fine
> poisoning due to the modified PMDD I used is not likely not to a
> the tetras and various fish which I have in the tank in addition
> discus.

The question is why were there sick fish in your tank to start 
with.  In my experience, healthy fish put into a healthy planted 
tank _rarely_ get sick.  Even when they do, it tends to be an 
isolated occurance... for instance, a single fish damaged in some 
way, or perhaps very elderly, that succumbs to an infection.  It 
has literally been years since I've had any sort of infection that 
spread from one fish to another in a planted tank. (Incidentally, 
in that particular case, it was a disease that came in with some 
wild-caught West African fish which I had quarantines, but 
obviously not for long enough... I ended up having to tear down 
and sterilize the tank) :-(

> In addition, you are writing things as if I have been adding cya
> First of all, the substitutions I made were thought in advance a
> compounds well known to be safe: PH Down (at a fraction of the r
> dose) for HCl, and potash muriate for K2SO4, which I can't find.
> before I decided to use potash I posted a request for hydroponic
> companies (for the micronutrients and the K2SO4) without receivi
> and since I was concerned with the chloride in the potash I then
> person on the list who successfully used potash in order to know
> he used.

I feel that it is important to make _everyone_ (particularly 
novice lurkers) aware of the potential dangers of random 
introduction of chemicals into the aquarium.  If you _want_ to 
experiment, it has to be done slowly, over a period of months or 
even years, changing just one parameter at a time.  Otherwise you 
are playing russian roulette.

> I did not use KNO3 on the basis of some postings, including your
> remember well, saying that beginners like me have normally plent
> nitrogen anyway. 

Yes, but you only got part of the message, because then you 
_added_ phosphate, which is usually a larger part of the algae 

> As I posted with no answer yet, I do not know w
> for the micronutrients with iron (can you please give me an opin
> this?).    

You have to understand that this list is a group of fellow 
hobbyists who are here to enjoy each others company and exchange 
information.  Everyone here has "real" lives and responsibilities. 
 There are three possibilities that I can think of that you didn't 
receive an answer.  1.)  It could be that the people who _had_ the 
answer just missed your message. 2.) It could be that no one 
_knows_ the answer. 3.) It could be that you didn't supply enough 
information for anyone to make an educated guess.  Maybe I missed 
it, but I haven't seen enough information for me to hazard a guess 
why your iron levels are so high.  It doesn't sound right.
> Overall, although I am not able to modify the PMDD on the basis 
> thought molar concentrations of one thing or another, I feel I b
> adequate safety margin using proven compounds within the doses u
> successfully by others. Can you point out something specific to 
> otherwise (by E-mail, if it is not appropriate for this list)?

I already have.  Don't add phosphate to a trace element mix.  ALL 
trace elements must be provided in amounts that are adequate for 
plant growth.  A deficiency of _any_ trace element will become the 
limiting factor for growth.  The only way (other than luck) to 
acheive this is to use a properly balanced mix.
> In general, I certainly agree with the recommendation to be very
> about changing things around, and I do feel like an apprentice s
> wish certain compunds would be easier to find. However, some foo
> is part of our hobby, and it should be tolerated if reasonably s
> you agree that many of the commercial preparations being adverti
> by the tons are much more dangerous than my ASRFF??!

I'm not sure of that, but I'll certainly agree that there are many 
commercial products that are at best useless, and at worst 
harmful.  OTOH, there are some very good, reliable products on the 
market as well.

For those who want to experiment, that is their choice.  IMO, it 
is best to use the tried and true methods until you have succeeded 
with them.  Once you have mastered the basics of planted tank 
maintenance and have some experience under your belt is the time 
to branch out into experimental methods.

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA