and others for the kind comments. Wish more of you were there. Great to hang with Immortal1 and a few others in Seattle.
I've been called many things but I post as Saxa Tilly here and as Pikez over at Barr Report.
The first two-thirds of my talk was a summary of my Rotala Kill Tank experiments, which was set up to figure out why Rotala stunt so often for so many people. The last third was a summary of takeaways from my 'social media database' and finding commonalities in tank conditions of experts and semi-experts who grow Lythraceae (Rotala, Ammannia, and Cuphea) without any tip stunting under a wide range of conditions.
I hope the AGA makes the video available for streaming soon for non-attendees. I pushed my 1 hour time slot to 1:15 but even then, I was unable to get to some of the nitty gritty details. I was unable to go into details on Marcel Golias' results, which I feel deserves more attention. His experiment design is damn near flawless and no one else has come close, which means you can use his results as a jumping off point for future experiments.
Having said that, I am just as interested in finding out WHY Tom Barr is successful. The current state of the hobby says Tom's approach is successful because of very high CO2 and excellent maintenance. Sure, good CO2 and great maintenance are important, but that is a woefully inadequate and inarticulate explanation for the success of that method. The 'it works in my tank, therefore, critiques have been falsified' is an equally unacceptable retort. Arguing about these things is a hobby onto itself here on TPT and FB.
Anyway, it turns out there are surprising commonalities in approaches. I haven't cracked this nut yet and I don't have all the answers. There are two conditions that seem to drive chronic tip stunting - no, it is not CO2 or maintenance - and they are the bicarbonate content of the water (KH) and WHERE the nutrients are provided to the plant.
The easiest way to stunt these plants (worst case scenario) is hard water with high KH + inert substrate + high water column dosing. If you move the nutrients deep into the substrate and leave the water column completely unfertilized with NPK + traces, there is little or no stunting.
On the flip side, if you have very low KH, EI ferts and inert substrate do not cause stunting, at least in R. wallichii.
There is a hypothesis that suggests that HCO3 interferes with nitrogen uptake. This needs further work. There are also published papers (I've only read the abstract) that suggest high bicarb content interferes with calcium transport to shoot tips. Iron too. It appears that these bottlenecks are bypassed if you root-feed...again, possibly due to nutrient selectivity of root cells vs leaves.
Clearly, there's still lots to unpack here. But at least now I know EXACTLY WHY Tom's approach is successful. I also know why Marcel and Happi are equally successful. It all makes sense to me anyway.
Kill Tank Experiments continue...I'm scheduled to speak at Chicago in September. CAPS club. Don't know details yet.
- Vin (find me on FB and message me with anything that might be relevant).
we might have answer to several questions as of now, we still need to explore more and still need to answer some of the unanswered question including the one you have mentioned, but We are not that far away from answering those, i wish Marcel Himself was here, am pushing him to come back in the hobby again, we still exchange emails and i am hoping that one day he will return and shed more lights, even though his website always shed tons of lights on these topics.
there are many plant sp. which are prone to stunting, Ammania, Wallchi etc for example, we can actually grow them in majority of waters, i have seen some people grow these even in Utah's Hard tap water, this water here is rich in Ca, Mg, Cl, S, Na etc as well, but wallachi seems to grow quite well in it, anyways for me personally i can grow almost any plant, i have tried wide ranges of fertilizers, chemicals, ratio, chelated, non chelated, organic, non organics etc, in my experience plant grow well if they have to spend less energy to derive nutrients, Urea vs KNo3 for example, you will constantly be trimming wallachi no matter if other nutrients are present in bit higher amount, i have already covered most of these topics in the past and am sure people can easily find it. we can certainly grow plant in inert substrate without root tabs if water column dosing is derived from easily available nutrients. Ammania sp. obtained very fast growth but still had some minor leave twist, which vanish when that same dosing become less and more frequent instead of one single dose. we put Marchner ratio to test (require pure Ro/DI water) the results can be seen in Marcels website or the pic i pointed out earlier, where the entire solution was totally based on this ratio, where N was based on 50% in NO3 and 50% in NH4 form, results were quite amazing even with such a high doses of N and little Micros, when i tested this under different environment such as water with added Ca, Mg, Co3, KH etc, i started to see issues again, first one was twisting in some sp, Fe deficiency etc started to appear quite often, when KH was reduced, good results appeared again. i was able to pull off different results with different methods, if one really want to grow plant they should keep the KH low, like i have said before, if KH could interfere with the fertilizer solution, imagine what it might be doing in your aquarium. Marcel have covered the Co2 part as well, where he talked about higher co2 act like steroid and actually make things worse for plant and contributes to twisting and other issues in plants, he recommended 15-20 ppm for Co2.
here's another quote from him, which is referring to that pic i posted earlier, some of these were personally shared with me, they are subject to change as he have mentioned " preliminary" :
"First two tanks (from left to right) are EI recipes, tank #3 and #5 are Marschner's recipes (the tank #5 runs on the recipe I have gave you; the tank #3 runs on 2-times more concentrated recipe which had the same amount of nitrogen as EI recipes).
So now we seem to know what are the optimum ratios of elements for (at least some) plants. Our findings are only preliminary yet, but it seems that plants really prefer to uptake nutrients in a well-balanced ratios. This is not our own discovery. Scientists found this out long before us, but we were not sure if it applies for aquatic plants also. Some hobbyists recommend to add an extremely high amounts of nutrients into our water thinking that the excess is best for them, or that it is not detrimental. But this is not true. It is a proven fact that the terrestrial plants grow best when the nutrient levels are low, but continuous. To ensure a continuous supply of small amounts of nutrients to the terrestrial plants is a problem, but not so in our tanks where we can add all the essential nutrients on a regular basis. So we have try it, and found out that the continuous supply of a small amount of nutrients is the key to the best growth even with the aquatic plants."