I don't think that three days is all that fast for a deficiency to show up in fast growing plants. Adaptation plays a role and is working against the plant already too, with both the stress of adaptation and the lack of some nutrient, I can see hygro dying off that quickly without a problem. It seems to me that you have a tank that is probably extremely low on some key nutrient(s) (in the water column, at least), growing only slow growing root feeders that are already well adapted, and then you add fast growing leaf feeding plants to it. It only seems logical, at least from what I understand of this setup, that they could die. Crypts and other slow growers can do just fine in tanks where other faster growers would die off. Why not add another slow growing root feeding plant instead to see what happens?

Depends on the nutrient.

3 days is plenty for N and CO2.
Not for PO4............or Fe etc.......

Regards,
Tom Barr

Carissa,

Two of the four plants that died were vals and E. tennelus, which in normal conditions grow fairly fast after they are established. The former hung on for several weeks before I removed it because it was falling apart without producing any new leaves. The latter just got smaller and smaller and just about disappeared before I removed it.

I am pretty sure that the water column nutrients are OK.
If anything is lacking I'd think it would be in the 4 years old soil substrate, but the crypts are doing well, so . . .

Bill

I never had good success with vals, even with fertilizing everything. Not sure why, probably light in my case.

Why would you think that you have enough of all your nutrients in the water column, if you haven't been fertilizing? I don't know, it just seems logical to me that if stem plants and fast growing plants die but slow growing root feeders are living, that the water column must be somewhat deficient and maybe the substrate too for that matter, but maybe not so much. Maybe try a sword or some different crypts? You could at least rule out some causes, if you could get something else to live.

An 8 to 24 week test would work in a lab but not in my living room. Would the results of one cycle be of any value?


My only interest is to try to find out why the plants died. Allelopathy seems to be the only possibility left. Lighting and nutrients are OK. Carbon is low but the crypts are thriving. I can't think of any other cause, and no one else has suggested one.

It well might be that allelopathy manifests itself more in an enclosed environment like an aquarium more than in nature. My dog will affect my lawn; when we walk in the woods he doesn't affect anything noticeably.

Perhaps plants in aquariums act differently than they do in the wild?



Well, I don't know either. But one can infer an answer to a problem by eliminating all other possibilities, right?

The problem is, why are those plants dying? Allelopathy is one possible answer. Ruling out inadequate light and insufficient water column nutrients, in the environment that i have described, what else could it be?

Bill

Your nitrate test kit is no longer accurate. And, you are very low on nitrates, because the crypts are now big enough to hog all that is there. Without nitrates and no established root systems, the newly planted plants die. That is my hypothesus.

Since excess nitrates do not harm either the fish or the plants, within the limits of the EI fertilizing routine, you could dose about 20 ppm of nitrates and see if the plants begin to do better. And, just to be sure you have sufficient carbon for the plants to be able to use the nitrates, you could dose a water change dose of Excel. Just to be sure your phosphate test kit is still valid, you could also dose about 4 ppm of phosphates to eliminate that as a problem. I'm betting the plants will do much better then. Don't ask the amount of my bet - I'm chicken!

Perhaps to falsify it, but I'd still want a few more examples before moving forward.
Still, it would not look good for the allelopathy folks if no response was seem either treatment


Depends on how bad you want to answer that question or just move on and redo the tank..............always a trade off there...... and most chose to redo the tank.


Then the activated carbon would show a much greater impact based on this line of thinking.......but near as I or anyone else can tell, it does not.


Manures will too, and concentrated salts from urine will as well, this is known in agriculture................and documented going back 1,000's years. you are adding a lot more to one single area. But how does a plant evolve such a compound give in nature, it offers no use? This shoots the allelopathy theory of evolution in aquatic plants in the foot. Given most aquatic systems where plants are found are seasonal, the water is always changing volume and the levels move all over the place..............and where it is not, the system is massive and or is unidirectional, river/stream etc.

Otherwise in moves all over.
Thus the location and volume of the system changes massively.


I'd agree with that, they are pretty fat and happy in most cases.



Well, the obvious one is that the system is CO2 limited. Plants have different abilities to acquire CO2..........they take time to adapt to each location and flow pattern.........

A simple difference between that, and also, how can you be so sure about all the other variables as far as nutrients?

I have a rough time ruling it out with the testing I've done.......I can with EI dosing for limitations.........but that's more for CO2 enriched systems, but I can modify and apply it to non CO2 systems at a reduce rate also and test from there.

Observational data alone is good and all, but will only get you so far and not help you get that much closer to cause.

You need to do a manipulative test to see.
and you have low replications as well, one

So.......I'd just redo the tank.

Regards,
Tom Barr