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Above 8
- Thread starter hax47
- Start date
Hi all,
I've seen this reticulated, net like, chlorosis a lot in my own tanks, and it was the major reason that I've gone to using a <"hybrid Duckweed Index">.
You can see it in <"Frogbit taken a turn"> and also the recovery after <"a change in chelator">.
cheers Darrel
It looks like the plants have been <"iron (Fe) deficient">, but are now recovering.
I've seen this reticulated, net like, chlorosis a lot in my own tanks, and it was the major reason that I've gone to using a <"hybrid Duckweed Index">.
You can see it in <"Frogbit taken a turn"> and also the recovery after <"a change in chelator">.
cheers Darrel
Hi,
I insert them as any other images.
Thanks for your input, I really hope that they are recovering.
I am not sure if I understand the hybrid index, though. I followed the links, but still, I am unsure. Do you mean that you overload the Fe/Mg dosing, so you should not worry about it, and any problems would reflect the lack of other nutrients?
Or did you mean to ask how I made the gifs?
Hi all,
It is just because I rely on the <"leaf size, vigour and greenness"> of Amazon Frogbit (Limnobium laevigatum) as an indication of when nutrients are needed. There is more explanation here: <"The scientific background to the "Leaf Colour Chart"">.
The problem with iron (Fe) is that <"it isn't mobile within the plant">, and there is a lag phase before you get new healthy growth occurs <"if iron is deficient">. I want to avoid that lack of growth, when everything else is available, but iron is <"Liebig's limiting nutrient">. I can forestall this happening by adding plant available iron on a more regular basis.
Because I don't dose fertilisers regularly, the magnesium (Mg) addition is purely because I use rain-water in the tanks, occasionally with a small volume of <"added tap water">, and <"neither of these supplies very much magnesium">.
Because magnesium is mobile within the plant I could wait until I see chlorosis in the older leaves (and they would recover), but "Epsom Salts" (MgSO4.7H20) are cheap and <"I just sprinkle a little in"> when I add the FeEDTA. I don't see a downside to this, even if it isn't strictly necessary.
cheers Darrel
Yes, exactly that.
It is just because I rely on the <"leaf size, vigour and greenness"> of Amazon Frogbit (Limnobium laevigatum) as an indication of when nutrients are needed. There is more explanation here: <"The scientific background to the "Leaf Colour Chart"">.
The problem with iron (Fe) is that <"it isn't mobile within the plant">, and there is a lag phase before you get new healthy growth occurs <"if iron is deficient">. I want to avoid that lack of growth, when everything else is available, but iron is <"Liebig's limiting nutrient">. I can forestall this happening by adding plant available iron on a more regular basis.
I think they are. I'm actually not very good at doing this, and often my Frogbit plants show some signs of iron deficiency and recovery (like yours). I'll be honest I'm a <"pretty lazy and shoddy aquarist">.
Because I don't dose fertilisers regularly, the magnesium (Mg) addition is purely because I use rain-water in the tanks, occasionally with a small volume of <"added tap water">, and <"neither of these supplies very much magnesium">.
Because magnesium is mobile within the plant I could wait until I see chlorosis in the older leaves (and they would recover), but "Epsom Salts" (MgSO4.7H20) are cheap and <"I just sprinkle a little in"> when I add the FeEDTA. I don't see a downside to this, even if it isn't strictly necessary.
cheers Darrel
Some of you probably know that I am putting some effort into understanding the gas exchange processes in my aquariums, especially about CO2 (see the experiments). Of course, I also do some CO2 testing in my aquariums, especially since I started dosing carbonated water together with the micros; it is important not to go too high with CO2 since it could be toxic. I think, that since this way the dosing is well-controlled, if done right, it is a safe way of adding CO2. It also produces fluctuating CO2, which has been accused of leading to algae, but I am unsure if this is true.
In my smaller tank, pH goes down to about 7.3-7.5 after dosing and goes up to a little under 8 by the evening. If I don't dose the next day, I have 7.8 as a start, and it goes up to about 8.15. At first, I dosed every other day, but for about the last ~3 weeks, I have been doing it daily, except on water-change days when the water change supplies the CO2, approximately at the same level.
Last week, I decided to start writing down my pH measurements to get a pH/CO2 profile. So here they are; the individual points are not from a single day (except for the points during the first photoperiod when I was home all day), but combined from multiple days :
pH
The light periods are indicated with the yellow stripes.
Converted to CO2, calculated with the constants from the paper @Andy Pierce recommended, I guess this qualifies for fluctuating CO2 levels:
So, the CO2 goes up to 20-30 ppm after adding carbonated water and sinks to about 12 during the first 4-hour period. However, the drop is smaller during the second period, from ~10 ppm to ~5 ppm. This is consistent with what I have seen before, that the CO2 consumption rate depends on CO2 concentration at the same lighting. It seems to me that the plants have a higher photosynthesis rate at the same lighting intensity when the CO2 is higher. So maybe the lighting is overdosed here during the second period, compared to CO2 levels.
I am thinking of adjusting the light intensity so that they would get slightly more light when the CO2 is higher in the morning (70% instead of the current 60%) and a bit less (50 or 40% instead of 60) during the second period. When I changed the lamps to these, I let them run at 70% for both periods, which led to some pearling but also boosted the algae growth. I suppose I could drive the photosynthesis in the morning with stronger lighting and still avoid damaging the plants in the evening.
_Maq_
Member
Two points:
(1) CO2 concentration decreases faster in the morning period because the difference between your tank and air equilibrium is higher, therefore gas exchange is higher, too.
(2) Wetzel - Limnology assessed that photosynthesis is less intensive in the afternoon even if the CO2 concentration is maintained constant. Based on some experiments.
Good point, this contributes to some degree for sure, but based on my previous experiments, I think a big part of the decline is due to photosynthesis. Compared to this previous measurement (here water change increased the CO2) in the same aquarium, I now have a tighter-fitting lid (so less dissipation of CO2 to air). Nevertheless, I expect some equilibration between the water and the headspace in the first hour or so. Here, I think the first decline till about 11 ppm, before the lights were on, corresponded to the equilibrium in the whole aquarium space (water + headspace), and/or equal distribution of CO2 across the whole water volume:
Interesting, I guess even plants have some circadian rhythms that control their metabolism during the day. So it might not be just the CO2, then. This may also align with the decreased sunlight in the afternoon, I guess. Not sure if the experiment was conducted under sunlight, but even if not, some parts of the circadian rhythm regulations could be genetically encoded, which might have been adjusted over millions of years. Do they have a photosynthesis intensity profile over the entire photoperiod? I wonder if the morning is the ideal time to push the lights or around noon.
_Maq_
Member
I don't recall the details.
Usually, CO2 gets quickly depleted during early hours. In the afternoon, plants are largely relegated to bicarbonates, which are less attractive for all of them. We may speculate that plants photosynthesize "as intensely as they can" in the morning - while CO2 is readily available - and they "know" that late hours will be less favourable.
But the reasoning may go still other way, maybe. In the morning, plants have a long list "TO DO" for which they need to obtain new sugars. Once the most urgent needs are saturated, photosynthesis may run on more relaxed pace.
I don't know, these are just assumptions, and, as far as I can remember, even Wetzel was not very resolute in making his assessments. Wetzel is a bit old (1997 last ed.), perhaps newer research elucidated this issue better.
I did a quick superficial search on this, and it seems that, indeed, sugars partially regulate photosynthesis, and one way of doing that is by preparing the plant for the light in the morning (i.e., modulating the diurnal cycle phase). It could be logical if the carbohydrates would inhibit photosynthesis also when the CO2 is not limited, but I did not dig that deep into plant metabolism. Also, it seems that there is a midday depression in photosynthesis in terrestrial plants, which is partly attributed to the stomatal closure (which limits water evaporation during the temperature rise) and the decrease of intercellular CO2. In aquatic plants, this is probably different, but still, in some waters with dense vegetation, the decline in CO2 during the day could have a similar result. If I recall correctly, I have seen such plots on this forum, but there is also one in this paper (Figure 3.).
I guess I could check if the CO2 levels limit photosynthesis (CO2 consumption) or if it is regulated otherwise in my aquarium if I gave another dose of CO2 before the second photoperiod and compared the two CO2 dissipation curves.
So, I tried to inject two doses of CO2 before each lighting period. The setting of the right CO2 dose before the second period needed some trial and error; therefore the swings there.
The second CO2 decline was not as steep as the first; the calculated k value is about half compared to the first lighting period (0.0076 vs. 0.0036). However, this should not be considered evidence for lower photosynthesis in this period; the experiment would probably need more repetition and more control over setting stable, identical initial CO2 levels before the lights go on. Also, the headspace CO2 was probably different before each dosing, which can also affect the results. This way, I can say only that the tendency in the photosynthesis rate decline was similar to that of what @_Maq_ referred to in another experiment. Or even a more correct way to put it: this measurement did not disprove that observation.
Based on the declined CO2 by the second lighting period with a single dose, I changed the intensity to 70% in the morning (from 100W, 2000 lumen/20 W 6500K led strips) and 50% in the evening. I don't have any hard evidence that this would do any good, but I assume if the CO2 levels are low, the light intensity should be also lower. At least, based on what I have read so far, too much light compared to CO2 (or intensities higher than those required for photosynthesis) could damage the plants. I am unsure what to expect, but it would seem logical to get a similar CO2 decline in the afternoon, even with lower intensity. I will observe what happens and go from there. My gut tells me that I could check the CO2 levels at the end of each day and set the durations so that a certain CO2 level/pH would be reached by then (for example, a pH above 8), and also set the intensities in such way, to match the changes in the pH/CO2 daily profile. Then, re-evaluate periodically as the plants grow or if something goes off in the tank.
The second CO2 decline was not as steep as the first; the calculated k value is about half compared to the first lighting period (0.0076 vs. 0.0036). However, this should not be considered evidence for lower photosynthesis in this period; the experiment would probably need more repetition and more control over setting stable, identical initial CO2 levels before the lights go on. Also, the headspace CO2 was probably different before each dosing, which can also affect the results. This way, I can say only that the tendency in the photosynthesis rate decline was similar to that of what @_Maq_ referred to in another experiment. Or even a more correct way to put it: this measurement did not disprove that observation.
Based on the declined CO2 by the second lighting period with a single dose, I changed the intensity to 70% in the morning (from 100W, 2000 lumen/20 W 6500K led strips) and 50% in the evening. I don't have any hard evidence that this would do any good, but I assume if the CO2 levels are low, the light intensity should be also lower. At least, based on what I have read so far, too much light compared to CO2 (or intensities higher than those required for photosynthesis) could damage the plants. I am unsure what to expect, but it would seem logical to get a similar CO2 decline in the afternoon, even with lower intensity. I will observe what happens and go from there. My gut tells me that I could check the CO2 levels at the end of each day and set the durations so that a certain CO2 level/pH would be reached by then (for example, a pH above 8), and also set the intensities in such way, to match the changes in the pH/CO2 daily profile. Then, re-evaluate periodically as the plants grow or if something goes off in the tank.
Hi all,
That is partially why I like a <"floating plant from Varzea lakes etc">. they have access to atmospheric gases and are adapted to huge amounts pf PAR.
cheers Darrel
In the <"right conditions"> photosynthesis will deplete the CO2 in the water <"pretty efficiently"> and the pH will rise.
You get photorespiration as well in C3 plants, this is partially a mechanism for <"reducing damage from photooxidation"> (back to Clive's <"photon torpedos of light">). Light levels will change during the photoperiod and will always be most intense at midday <"https://www.ccfg.org.uk/wp-content/uploads/2017/11/Conf09_PBurgess.pdf">
That is partially why I like a <"floating plant from Varzea lakes etc">. they have access to atmospheric gases and are adapted to huge amounts pf PAR.
cheers Darrel
Andy Pierce
Member
Nice with the Hydrocotyle tripartita. I might have to try that one. I've had what feels like more not-success than success with plants in the "liquid rock" setup, but some good ones for me have been Bolbitus heteroclita ‘Difformis’ (does surprisingly well), Helanthium bolivianum ‘Quadricostatus’ (pretty bombproof), Limnophila sessiflora (very nice, likes more light rather than less).
For the CO2 piece, what happens if you keep the light on the whole time and periodically reboost the CO2 levels? Do you find sharpest consumption in the first interval, less in the middle and least at the end? I'm also doing the split lighting periods but not really for any type of good reason other than liking to see the aquarium lit-up and not wanting too much light during the day when I'm off at work (if "too much light during the day" is even a thing).
For the CO2 piece, what happens if you keep the light on the whole time and periodically reboost the CO2 levels? Do you find sharpest consumption in the first interval, less in the middle and least at the end? I'm also doing the split lighting periods but not really for any type of good reason other than liking to see the aquarium lit-up and not wanting too much light during the day when I'm off at work (if "too much light during the day" is even a thing).
This photorespiration is a new thing for me... I feel like the more I dig into something, the stronger my feeling is that I barely scratch the surface with all I understood so far. From a quick search, I see that ammonium production is one of the steps in photorespiration. It might be a dumb question, but what do you think, could ammonia production in plants, due to intensive lighting and photorespiration, play a part in algae growth in aquariums? I know this ammonia is produced intracellularly in plants, but NH3 (unlike NH4+) can diffuse through cell membranes. Also, when searched specifically, I found this, but not much else on the topic: rice leaves seem to release NH3 in relation to photorespiration.
I do not know why, but tripartita is the one that enjoys my setup the most, I had to trim it back this weekend. This is the mini version; I had the regular one in the other aquarium before, but it did not grow well; it was with less light and CO2, though. I tend to throw plants into the tank and see what sticks, and this one clearly does well. Thanks for the plant tips, I am actually making plans for a Dutchish-style aquarium and added them to my list of to-be-considered plants. Am I right that the Bolbitus has a bit darker green color?
That would probably be the better way to test this question; it would take out the effect of some of the variables for sure. Dosing at the same pH levels multiple times and watch how long it takes to get back to the same pH.
My reason for the split period is the same; therefore the early lit-up during my morning coffee session and the other one when I arrive home.
_Maq_
Member
I think it's unlikely. I don't think ammonia is the algae trigger, in the first place.
One of many arguments: Due to dissociation curve of ammonium/ammonia, algae would grow much more prominently in basic environment, and below pH = 6.5 would be near impossible. Obviously, this is not what we observe in our tanks.
Ha same here, I threw the plants into my tanks and see what sticks, some do better than others. Hydrocotyle tripartita is one that does well in my 2 tanks without CO2, and funny when I put them in my vivarium near the water surface ('access to Co2'), they don't particularly do well...
Planning for a Dutch style tank you say? Recently I have been just thinking if I could start over my dutch tank, I would go for various types of Ludwigias aha (instead of the Rotalas I chose). More reliable presentation of colours and less finnicky.
I am eyeing to get some Bolbitus for my upcoming nature style tank, I hope it is not a finnicky plant as I have not used it before hmm
Hi all,
cheers Darrel
I only have <"experience in soft water">, but for me it is the <"ultimate low maintenance plant">.
cheers Darrel
Andy Pierce
Member
Here's what mine looks like. Bolbitus heteroclita ‘Difformis’ circled in cyan in the photo.
Regarding the CO2 consumption later in the photoperiod, I remember reading that people concluded that photosynthesis was probably reduced in the afternoon based on the observation of the accumulation of CO2 bubble in CO2 reactors. During the first hours of the photoperiod, the reactor would dissolve all the CO2 injected, while later the gas would start accumulating.
