Tom Barr - about 100 ppm of nitrate.

Ammonia in water can be toxic at elevated concentrations. The few studies that have been carried out on the toxicity of ammonia to freshwater vegetation have shown that concentrations greater than 2.4 milligrams of total ammonia (i.e., ammonia plus ammonium) per litre inhibit photosynthesis and growth in algae (e.g., World Health Organization 1986). In experiments with rooted aquatic plants, ammonia reduced the length and weight of roots and shoots (Stanley 1974; Litav and Lehrer 1978). There have been no conclusive toxicity tests on saltwater plants.

In most surface waters, total ammonia concentrations greater than about 2 milligrams per litre are toxic to aquatic animals (Mueller and Helsel 1996), although this varies among species and life stages.

Although nitrates in water are relatively non-toxic, nitrate concentrations in the range of 5–50 milligrams per litre have been shown to be lethal to eggs and, to a lesser extent, fry of salmon and trout species (Kincheloe et al. 1979).

These tend to be the most sensitive species as well as developmental stages.
If fish are able to breed and raise fry, then it itvery likely there is little if any impact upon the fish at a particular NO3 ppm level. This is the lowest range for any NO3 toxicity fish species that could be found and does not apply to warm water fish. Even still, the range is quite large evene the worst case senario, up to 50ppm but as low as 5ppm for the most sensitive stage and species.

Pierce et al 1993 suggested:
Previous studies have indicated that long term exposure to nitrate-N levels above 100 mg/L may be detrimental to fish. This study was undertaken to assess the acute toxicity of nitrate to five species of marine fish, while efforts were taken to reduce the nitrate concentration in the recirculating systems.

Marco 1999, suggests that warm water species have a suggested range of "recommended levels of nitrate for warm-water fishes (90 mg N-NO3-/L)"

That's N as NO3, so 4.4X 90.

Quite high.

here's a link to the common fathead minnow:
SETAC Journals Online - ACUTE AND CHRONIC TOXICITY OF NITRATE TO FATHEAD MINNOWS (PIMEPHALES PROMELAS), CERIODAPHNIA DUBIA, AND DAPHNIA MAGNA

Do the math for the conversion of N-NO3 to NO3 for ppms.

Quite high huh?

Still not convinced?

Well take a long look at the Fish and NO3 toxicity section in this good review paper:

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Remember to multipy by 4.4 to get NO3ppms rather than N-NO3!

As you can see, the ranges are extremely high and that warmer water fish tend to have a greater ability to withstand NO3 levels as well. When fish breed and fry ar eproduces, this representst the behavior(positive good) and the most sensntive life stanges. I routinely have this occur in such higher NO3 tanks.

Now some have made claims that my advice concerning EI dosing is bad for fish and they have not supported with test, with primary research, nor applied plant tank experience neither over short term nor over long term test.

Now I ask them to stand before others to show their evidence rather than preceptions to show and prove otherwise.

What I hear from:

1. Banther about less is better(but they rarely say how much less)
2. No supporting primary research(still waiting for one review)
3. Advice and heresay from other web sites
4. Toxicity citations about humans, not fish
5. No toxcity test of their own to deny/confirm(kind of sad, they make claims and then do not test them)
6. Claims that behaviors change(how do we measure this?)

The burden of proof is upon the critic here.
I've done my job supporting my advice, the real question folks should ask: have the critics done their job supporting theirs?

I just don't see it.
They get irritated when I go after them about it and they scramble, take it personally etc, but the bottom line is not a personal issue, it's about the fish, the hobby and the methods we use the advice that is given.

I do not roll over and accept their criticism when it's plainly wrong.

Should I?

Regards,
Tom Barr

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The issue I have with a tank rich in nitrAtes is that it is too stable and ready to crash if something goes wrong. So from what I understand, it's not the nitrAtes that are the real devil here. It's that in most tanks where you find nigh nitrAtes you also find pH crashing and mulm building up to dangerous levels as well as high TDS which compromises the osmotic health of the fish.