Cryptocoryne Wendtii and Allelopathy

In my limited experience, it seems to me that crypts (at least the wendtii type) are very forgiving. The other plants you are trying are not as much so. You would know best what the difference is between this tank and the ones you are getting the other plants from.

 

Hi Bill,

Have you had a chance to gravel vac that section? If compacted heavily, it can produce hydrogen sulfide which is toxic to all.......

IME I had 1/2 of my 180 with wendti at one point and did not cause any issues. Was doing a bit of c02 at the time, regular floro tubes, but no other ferts using flourite. Was able to grow other things with no problems.

Clean out that side of the tank and ensure all old roots, etc is gone.

Then again try some of your new cuttings.

I don't think the wendti is inhibiting it.

I think the specific area is the problem.

Let us know.

 

Is it possible that the crypts are using up the nutrients in the water, but having a big root system, can continue to grow from root feeding? That would leave the newly planted vals and microswords short of nutrients, but without the roots needed to feed that way.

Also, I have always had problems getting vals to start growing when first planted. They almost always shed all of their leaves, leaving only a rooted stub. Eventually that stub sends out new leaves and the vals become the nuisance they can become. Since I have never had E. tennellus grow for me I can't comment on that.

 

My understanding is that higher tech tanks generally get more water changes than lower tech tanks. Which means that the level of allopathens, along with everything else, will be reduced.

Could that not explain allelopathy not being seen in high tech tanks?

Would a plant growing more slowly produce more or less allelopathen per unit of growth than a plant growing fast? Maybe there is a difference there, too.

Would a plant growing faster be able to cope with more allelopathens in its environment than a plant growing more slowly?

 

Bill,
I don't really think this is a good assumption. Instead of looking at allelopathy, which as far as I can see is akin to witchcraft, it would be more productive to troubleshoot the macronutrient content of the tank.

You mentioned that the 30 gallon tank is illuminated by 65 watts of Compact Fluorescent. If so this is just over 2WPG and really no longer qualifies as a low tech tank. Further, you noted that no CO2 is being injected. So a fast growing stem is placed in a high light environment without CO2 supplementation and it fails. I would conclude that the failure is at least in some part due to the inability of the stem to adapt to the low CO2 levels while being driven to high CO2 uptake via light energy input.

I think that every hobbyist has a tank wherein some plants do well and other plants struggle or fail completely. Some plants are more adaptable by having more efficient nutrient uptake and processing mechanisms. This adaptability enables them to succeed in a wider variety of environmental conditions, including more stressful environments than those with less efficient systems.

The crypts may have adapted to the tank conditions and have had 4 years to do so whereas a new plant may have difficulty under these conditions.

If you wanted to test the possibility of CO2 starvation you could add CO2 either by gas injection or by the addition of copious amounts of Excel. If you wanted to test the possibility of light driven starvation then you could insert say, a 30 watt bulb or otherwise screen the 65 watt bulb to reduce the amount of light entering the tank. A combination of these actions would probably work.

Additionally, it's unclear how you are determining the nitrate and phosphate levels. Are you measuring with test kits, or is that from your water report, or are you adding this amount weekly?

There is enough ambiguity to question the dynamics of nutrient/CO2 uptake within this tank configuration. Only when these conditions are verified, and when you are satisfied that the conditions for proper growth exist within the tank can we then move on to other possibilities regarding unknown assailants/agents.

What we do know for certain though is that rapid degeneration of plant tissue is a classic symptom of CO2 starvation often exacerbated by poor nutrition.

Hope this helps.

Cheers,

 

You could float the hygro. It should still grow fine since it's a leaf feeder. If it still dies, that rules out substrate poisoning (unless it's something getting into the water itself from the substrate). Hygro shows co2 deficiencies with holes/leaf loss. But usually you will still see new growth happening. It's not a hard plant to keep, but sucks up nutrients fast. I transplant cuttings from my co2 to my non-co2 tanks with just a slack in growth for a few days to a week until they get adapted again, at which point they continue to grow, albeit slower than in the co2 tank. If hygro dies on you, there's got to be some nutrient lacking there that the slow growing crypts don't have as much demand for and/or are getting it from the substrate, not the water column.

 

Just a minor quibble: plants with extensive root systems are not necessarily "root feeders", just as plants with few roots are necessarily "water feeders". Roots serve the purpose of anchoring plants in moving water, as well as feeding then, so those plants with roots may or may not depend on their roots for food.

Now, my two cents worth:
It seems obvious that something changed in your tank, and changed for the worse. Even a shortage of nitrates shouldn't cause the rapid decline you reported. In fact I doubt that any shortage would cause that.

I also doubt that allelopathy is the problem. So, I'm left wondering if something like chlorine, or chloramines could be involved. Or copper, except that would kill off the fish before bothering the plants. Perhaps a detergent residue? If you had the capability of doing a thorough water quality analysis of your tap water that would be my first suggestion. If not, then RO/DI water, reconstituted properly, would be my next suggestion.

On second thought, take my advice free! Keep the two cents.

 

You could try planting another crypt in there. The way you are describing it, it does sound like something major is amiss, not just a simple deficiency. If I had to guess right now, I would say that either there is something in the water, or too much of something in the water, that the crypts have adapted to, but other plants are having trouble adapting to. If it's allelopathic compounds from the crypts, another crypt should live fine, or at least as well as a crypt will do when transplanted, which might be hard to qualify.

 

Fast growers like hygrophila polysperma (you can't get much faster than that) will show deficiencies much sooner than slow growers like crypts. Their faster rate of growth means that they have a very high demand on nutrients, which shows itself very quickly if any nutrients are at semi-low levels; whereas a crypt can live under very low levels of nutrients, sometimes indefinitely, without any visible problems, especially if nutrients are available in the substrate and it has an established root system to get them already. I think that's the big difference between your crypts and the plants you are adding, besides some being fast growers, they are relying on the water column heavily for their nutrients, plus the stress of changing conditions etc. is not in their favor; whereas the crypts do not need to rely on the water column at this point, and probably have very extensive roots. The anubias are also extremely slow growers. In my co2 injected tank, I'm lucky if I see a leaf a month or every two months.