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I suspect that nutrients are quite different than CO2. Only plants with CAM metabolism can store C at night (think succulents, but there are others too). There are aquatic cam plants (e.g. this work). So, those plants are taking up CO2 at night, but supplementary dosing is still probably unnecessary because of the higher CO2 available from the continuation of respiration but cessation of photosynthesis. However, most plants can and do store nutrients, some even being luxury consumers that can store quite a lot. That process is independent of photosynthesis, however it may be dependent on the resistance of diffusion and thus could be impacted by any stomata and their closure. That said, I presume vascular plants are likely to be able to store higher levels of nutrients, which me be able to be be done at all hours. If this hypothesis is correct, then it would seem to me best to dose in the evening or even after the lights have gone off. It seems clear that algae are faster at taking up N and P from the water column, which is why I was wondering if they experience a trade-off with storage capacity, and thus timing of input might favor vascular species.
I am also struggling with this issue. I have chronically low N and P available to the plants and because of this they barely grow, leaving what little is there to fuel algal growth. It is my squirting in of the liquid fertilizer opportunistically that made me begin to consider whether the timing of in put was important. I've begun to err on the side of putting it in near lights-out.
Sounds like a nice aquarium you have! I had nothing in my water; it was devoid of anything useful to the plants as it turns out. That seems to have lead to no plant growth and plenty of staghorn algae (plus luxuriant carpet algae on the rocks, which I honestly rather like). I began by only using root tabs in hopes of feeding the vascular plants rooted into the substrate, and avoiding feeding the algae. I saw little growth. It was only after beginning to add liquid fert to the water column that I began to see plant growth, even of the rooted plants. Much to my surprise. Even more surprising, the dosing of the water column didn't result in an algae bloom, but has reduced the growth rate. This goes against everything I know from natural systems, where we have very good data, but I am going with it.
Thanks for sharing what meters you use! I always find that instructional to learn what others are finding success with.
I have no experience injecting CO2 into an aquarium. But from my very outsider perspective, when looking at the species that "require CO2", it seems they are ones that would prefer to be emergent in habitat. I've taken the view the CO2 lets you grow plants submerged that otherwise don't really want to be submerged permanently.
I understand that, and I am not running CO2. Oddly, this redo of the same tank, same substrate, same water added, nearly the same plants, and same light - completely different issues. Ah non-linear dynamics!
I've not come across that test. I might just have to pick one up. Thanks for the recommendation!
I like the idea of doing a draw down measurement. Valuable approach. Now if we could do it with labeled isotopes... Then we're in my wheelhouse.
You're a bit cantankerous aren't you? I think I like you.
Nope, I'm on a well. A well that suggests there may be a cave system somewhere beneath me for all of the calcium in the water, and had there been a bit more iron in the water, I might have scrapped the house and opened a mine. So, I use RO. Have a nice 5 stage home system. The RO water does not vary in a measurable way across time. I've been using this type of system here for 10 years and test the water at least 2 times a week. Although in the strictest of senses, you are correct, it is not the "same water" as they are unlikely to be the same molecules. I am being flip, of course.
While I suspect by most measures, I would be considered to have a "scientific mindset", I am still human and subject to the same cognitive pitfalls as anyone. You'd be surprised what you do and don't question as you are taking in new information. I find that when people are new to a hobby such as this, they tend to overthink, while not questioning what seems obvious to the experienced. I recently encountered this with a new member to a society for the cultivation of plants where I am a member. I have been growing these plants for... Well, I suddenly feel old when thinking about it in terms of years. This new member had clearly done a great of research to find the "right" way to grow these plants, and yet was failing to deal with some of the basics that would ensure success. He was highly focused on aspects that people discuss often, but are not necessary for successful cultivation. As he spoke, I realized I am at a similar stage with aquaria. I've kept them for years in my youth, but returning to it, I immediately over-thought everything while not questioning basics that I should have. This has lead me to have a planted tank that is very over-filtered, where the plants struggle but the algae succeeds. As I am teaching again this semester, I've been pondering how one imparts the knowledge that comes with experience to help move those still learning toward success. To be clear, I've not yet figured this out.
Would that perhaps be the gentleman who runs the "Aquarium Science" website? I've had some enjoyable conversations with him in the recent past.
I am a vocal advocate for free speech in all its forms. Though it's fair-weather, cause célèbre. I have a little saying about this topic that I will leave you with:
I've not looked into it much, but first pass I've only found tests for marine and not freshwater. Not the same test, but my pH runs 82.-8.4, I have the N hat trick of 0ppm (I can push it towards 5ppm of nitrate with every other day dosing), P at zero, K at 15, and a GH and KH of 8 each. My RO has nothing in it, or nearly, with a TDS of 4-6ppm. Nothing seems to keep my pH down. The RO pH is about 6.2, and though I realize it is a log scale, big water changes seem to leave the pH unchanged in ways I find vexing.
I still try. Rather the mantra of teaching in general I find.
I'd love to learn about that, so "Yes please!" In terms innovation, one of my committee members in graduate school who was eminent in the field liked to say that "If an old scientist tells you something can be done, you probably can do it; if an old scientist tells you that something absolutely can't be done, you almost certainly can do it." It's a bit of a creative take on the old saying that "old ideas don't die, old scientists do".
While the left has definitely taken center-stage as the language police of late, they by no means have a monopoly on curtailing the speech of others. It was not all that long ago that George Carlin was causing conservatives to clutch their pearls. These days the right does like to position themselves in opposition to the "oppressive" left all the way up to the point where they get offended that is. At that point, they both sound about the same. I wish people would realize that free expression is little more than your right to be offended by what others have to say. Not a great sales pitch, to be sure. But, it's a right we should all cherish. Still, I have to remind myself of this simple truth on occasion while rolling my eyes when listening to some.
