Hi Ed,
Sorry if I missed your point and went off on a tangent. The issue may boil down to; "at what point does the built up concentration of these inorganic compounds pose a threat to either fish health or induce algae?"
It seems we've each read the threads and newsletters and come away with slighty different interpretations possibly because we each have individual and different concerns. A possible point of view is to regard these compounds with trepidation and as possible toxins. The extracts that you pulled appear to be within this context. I read the same mathematical excercise Barr offered I my sense was that he was attempting to show that if you were concerned about build up, the water changes in the CO2 injection method would address this concern, however I did not get the impression that
he was necessarily concerned about some critical level of build up which would
induce algae. My sense was that if algae was induced, for example by CO2 instability, having high built up concentrations would be an obstacle in it's eradication. Perhaps that is a point which is also being missed.
I draw you attention to a recent Barr thread entitled "NO3, NH4 toxicity test on plants and critters"
http://www.barrreport.com/articles/3267-no3-nh4-toxicity-test-plants-critters.html
The results of toxicity tests show that the toxic level of INORGANIC NO3 for the common guppy was something like 4000 ppm, a completely over the top concentration level that we would never see in our tanks. For species such as trout or salmon the toxicity levels were closer to what we see in the tanks but we do not typically keep these species. Marine species were shown to be even more resistant to inorganic NO3 toxicity.
We ought to now be convinced that "... just adding chemicals without some kind of way of monitoring or regulating the levels..." is not going to cause a fish toxicity problem. Besides, we are not "just adding" the chemicals; the concentrations and intervals are specific to the tank size and to the type of tank and to the fish load. If the plants are healthy, and if they are growing then one can be assured that the concentration levels will fall.
Now Ed, really, I have to say that it would totally shock me if you were to insist that you or any beginner could not tell if your plants were growing, even if they grew at a rate 10 times slower than those in a high tech tank. I mean, we are in this hobby to grow plants. We'd better have some idea of what a growing plant looks like. As far as identification of nutrient deficiences, well, OK, fair enough, but I will say that even when I didn't have a clue how to grow tropical weeds I think I still knew that if a leaf was yellow instead of green something was wrong. Here is a link to help out with nutrient deficiency identification:
http://www.csd.net/~cgadd/aqua/art_plant_nutrient.htm
Allright, now lets have a closer look at this Barr extract:
"I truthfully do not know what levels of NO3 and PO4 (for example) cause problems for plants or induce algae in a fully planted tank. NO3 levels above 40ppm can cause fish health issues. PO4 at very high levels can influence alkalinity (KH) above 5ppm-10ppm."
If you were to closely re-examine some of his other threads and newsletters, I'm convinced that you would have a better context of what he is trying to say here. He is not saying that he doesn't know because he hasn't tested, he is saying that he hasn't found a concentration level high enough which caused a problem. In fact, he has tried massive concentration levels but as the journal links in that thread above demonstrates, he hasn't reached levels approaching 4000 ppm.
Thats why he didn't know. As it turns out, the toxicity concentration levels for these chemicals are so high as to be practically irrelevant, because if we stick to his dosing schemes we wil never approach these toxic levels.
There still appears to be total disbelief among many regarding the assertion that high levels of PO4/NO3 have no bearing on inducing algae.
Here is an extract from the Red Algae article:
QUOTE
======
A simple test was done by a hobbyist to see if Audouinella was caused by excess levels of PO4 in the plant aquarium.
Table 1 [this tables shows the experiment procedure and results/conclusion]
While not showing what causes a BBA algae bloom, it showed that it could not be caused by excess PO4, therefore there must be some other reason for the algae bloom. Thus aquarists can make a hypothesis, then manipulate and test it to see if their hypothesis was correct or not by isolating the system.
UNQUOTE
========
This is just a tidbit from the newsletter but it shows that high PO4 concentrations actually helps to force BBA into dormancy. The person doing the test actually saw a decrease in algae with increasing levels of PO4. He also saw increased growth as PO4 was increased. Amazing.
This test was performed with a 1ppm PO4 addition repeated 10 times so there is no data regarding actual build up concentrations. I myself have run tanks in the 5-10 ppm PO4 and with 70 ppm and higher NO3 (high light). I had no toxicity problems and I only got into algae trouble when I got lazy (and stupid) with the CO2 (i.e, running low without paying attention). It should also be noted that this was a Discus/South American tank.
Again, I have to declare that when you're running these concentration levels and you make an algae mistake, you make THE algae mistake and you are in trouble because your tank will be ravaged as if the Red army were rolling through it. I reiterate though that these concentrations do not
cause the algae.
I would also like to point out that the reason Barr advocates the large water changes is not because is so concerned about the INORGANIC chemical buildup, but because of the ORGANIC NH4/NO3/PO4 buildup caused directly as a result of the flora and fauna growth/metabolism. I believe that the colossal differences between organic and inorganic sources of nutrient buildup is still poorly understood, and it may even be the reason that hobby grade test kits are so diabolically inaccurate. When setting up a tank he advocates 3X weekly water changes of 80% or so. This is to directly combat the NH4 buildup as a result of the organic nitrogen cycle. This is the real killer in our tanks, NH4, not inorganic nitrate/phosphate.
In a non CO2 tank, you can do with only inorganic nutrient sources but Barr has proven that the plants have a preferential uptake of the inorganic sources and, at certain NH4 concentrations, the plants prefer inorganic nutrients over NH4. The implication of this is tremendous because that means the plants will allow NH4 to linger which means the algae have a better chance of getting at it.
So in fact Ed, you have a point in that if there are high levels of inorganic PO4/NO3 and if you do not have enough nitrifying bacteria the NH4 will likely induce the algae. This is completely different though than blaming the PO4/NO3 for the algae. This is why I am of the opinion that filtration is critical in the non CO2 tank in which you will dose ferts. I feel the organics should be left to nitrification and inorganics fed to the plants. I have never properly run a non CO2 tank though so I can't actually prove this opinion.
My contention therfore, based on study of the Barr articles/threads, as well as from my own empirical experience, leaves me in no doubt that one never
needs to test for these particular chemical concentrations since they pose neither a threat to fauna, nor can they be implicated as a cause of of algae.
Now, if one
likes to test, or if some level of comfort is derived from testing, then by all means, one should test. I caution beginners though, that it is very easy to start to rely on testing instead of having your focus on observing and learning about the very specimens you are trying to grow. The reason I dislike testing so much is because it makes us draw conclusions due to
correlations instead of allowing us to understand the complex reasons. Barr concedes to testing in that extract because he has a comprehensive and fundamental understanding of
causes.
Cheers,