Water Test Weirdness

[StandbySetting]

It would make sense that less energy is required, as it has a shorter distance to travel, and the Stomata are always open, where as primary active transport through the roots would require more energy as it has further to travel.

I've also read that foliar fertilisation is used to treat nutrient deficiencies on terrestrial plants as the uptake from the leaves occurs at a faster rate than the uptake from the roots, whether this can be applied to semi-aquatic plants is a different story, but they can't be that different.

I guess there's another part of the argument for large route structures, for some periods of the year Echinodorus is emmersed, so can't get its nutrients from the water column, I believe that the heavy root feeders idea is gauged on the size of root structure, after all, it is the plants with large root structures that are tagged as heavy root feeders.

 

[TwoTankAmin]

There is a difference between anecdotal evidence and science.

SUMMARY. The mobilization of sediment phosphorus (P) by three submersed freshwater macrophyte species was investigated on five different sediments. The study was conducted under controlled environmental conditions in lucite columns that enabled the separation of sediment and plant roots from the overlying P-free ‘complete’ nutrient solution. The species investigated (Egeria densa, Hydrilla verticillata, and Myriophyllum spicatum) had minor root systems (on a biomass basis), but were demonstrated to be fully capable of deriving their P nutrition exclusively from the sediments. Phosphorus absorption and translocation into shoots (i.e., mobilization) was substantial, and in some cases suggested a greater than 1000-fold turnover of interstitial water PO[sub]4[/sub]-P over a 3-month period. Sediment P mobilization, a function of both plant growth and tissue P concentration, differed considerably among plant species and sediments. Phosphorus release from the species investigated appears to be primarily dependent upon tissue decay rather than excretory processes. The mobilization of sediment P by submersed macrophytes represents an important aspect of the P cycle, and may affect the overall metabolism of lacustrine systems.

From http/onlinelibrary.wiley.com/doi/10.1111/j.1365-2427.1980.tb01198.x/abstract

One can discover a great deal of research on the topic by going to Google Scholar and inputting "aquatic plants + nutrient uptake". Be sure to change the setting to "Articles excluding patents" to avoid the clutter.

But lets look at another consideration- the plant vs algae issue. Alga have no roots so can only derive their nutrients from the water column. Thus the more one can keep the nutrients in the substrate vs the water column, the less chance the algae has to get at them.

There is also the of the fish keeper's efforts. I push a Jobes Spike under many of my plants once every few months at a cost of a few pennies and dose the water once a week after a water change. I bet a lot of folks who rely exclusively on water column dosing are spending a bit more money and a heck of a lot more time on their planted tanks?

 

[eaglesaquarium]

It would make sense that less energy is required, as it has a shorter distance to travel, and the Stomata are always open, where as primary active transport through the roots would require more energy as it has further to travel.

I've also read that foliar fertilisation is used to treat nutrient deficiencies on terrestrial plants as the uptake from the leaves occurs at a faster rate than the uptake from the roots, whether this can be applied to semi-aquatic plants is a different story, but they can't be that different.

I guess there's another part of the argument for large route structures, for some periods of the year Echinodorus is emmersed, so can't get its nutrients from the water column, I believe that the heavy root feeders idea is gauged on the size of root structure, after all, it is the plants with large root structures that are tagged as heavy root feeders.

This is correct. I use an algae based micronutrient fertilizer for my terrestrial plants. This fertilizer is used at three primary periods in the growth of an annual terrestrial plant - first true leaf emersion, when transplanting, when fruit set first starts.

 

[ian]

There is a difference between anecdotal evidence and science.

again, i'm sure the people in this debate understand this and are quite capable at critiquing evidence. Just because it's science, it doesn't mean it's good evidence.

I bet a lot of folks who rely exclusively on water column dosing are spending a bit more money and a heck of a lot more time on their planted tanks?

Not so true, EI nutrient dosing is cheap as chips and a weekly water change isn't that difficult.

 

[TwoTankAmin]

Both phosphate and nitrate can and do cause algae. The thing is just isn't because they are present in the aquarium but rather it is when excess phosphate and/or nitrate is present that algae issues arise. Now this is not only an idea accepted by Tropica, but I can provide quote after quote by some of the most respected and well known names in the aquatic plant arena who say this.

First lets just look at what Tom Barr wrote in a thread on his forum on 8/19/07:

So for low light tanks, high light tanks, CO2, excel, non CO2(but not marine planted tanks, the max range seems about 0.5ppm for PO4) etc, the excess PO4 is going to induce algae.

from post #8 in this thread The Barr Report

Or here is what Karen Randall wrote:

For those of a more scientific bent, or those trying to troubleshoot a specific problem, it is definitely worth buying good-quality test kits for phosphate and nitrate. Beware of inexpensive test kits, however. In many cases you get what you pay for, and inaccurate measurements can be worse than none at all if you base decisions on them. Nitrate levels in a low-light tank can often be as high as 20 milligrams per liter (mg/L) without causing algae problems, while phosphate can sometimes be as high as 2 mg/L under the same conditions without causing algae problems. In a well-lit tank, nitrate usually begins to be a problem if it approaches 10 mg/L, while phosphate can be troublesome even at 0.5 mg/L

From Plant Nutrition — Part 1


Regarding root feeding, Karen Randall writes;

In a tank with a gravel/laterite substrate, particularly in a tank without substrate heating, most people find that solid substrate fertilizers of one sort or another are beneficial. This is even more important in tanks containing heavy root feeders, such as Echinodorus, Cryptocoryne or Anubias spp.

from Plant Nutrition — Part 2

 

[StandbySetting]

Both phosphate and nitrate can and do cause algae. The thing is just isn't because they are present in the aquarium but rather it is when excess phosphate and/or nitrate is present that algae issues arise.

Nitrate and Phosphate have never caused algae, the theory that they do is a long debated issue, they will however accelerate its growth, I bet if you ask Tom Barr now he'll concur, Nitrate and Phosphate are always in an excess in my set up, the same applies to anyone dosing EI, whereby the aim is to keep nutrients at levels so that they're non-limiting, here's my tank, Phosphate at 2PPM, Nitrate at 40PPM (calculated not tested, test kits are not accurate enough) EDIT, just tested, registering at 40PPM on my Salifert test kit and no algae:

Head over to a planted forum and take a look, most set ups where ferts are added contain no algae.
A lack of nutrients is likely to cause algae however, as well as fluctuating or non-existent CO2 and ammonia.

For those of a more scientific bent, or those trying to troubleshoot a specific problem, it is definitely worth buying good-quality test kits for phosphate and nitrate. Beware of inexpensive test kits, however. In many cases you get what you pay for, and inaccurate measurements can be worse than none at all if you base decisions on them. Nitrate levels in a low-light tank can often be as high as 20 milligrams per liter (mg/L) without causing algae problems, while phosphate can sometimes be as high as 2 mg/L under the same conditions without causing algae problems. In a well-lit tank, nitrate usually begins to be a problem if it approaches 10 mg/L, while phosphate can be troublesome even at 0.5 mg/L

http/bobstropicalplants.com/Chuck/nov1997.html

This was published in 1997, aquascaping has come a long way since then and it's only in the past few years that the 'nitrate and phosphate cause algae' argument has been put to bed, the reasoning is stupid also, the general consensus is that this lake has algae, this lake also has nitrate and phosphate present, oh this must be the cause which simply isn't the case, even anecdotal evidence in this case is valid in my opinion, it simply disproves all of these hypotheses about the causes of algae being nitrate and phosphate. Out of Aquatic plants and Algae, Algae is the more adaptable, which is why this statement doesn't make sense either:

The trick is to provide enough of all nutrients to satisfy the needs of the higher plants, while limiting excess nutrients that could feed unwanted algae.

 

[ian]

N and P don't cause algae and Tom Barr didn't write that they did. We know that Ammonia and light cause algae blooms. That Karen Randall stuff is to old school now.

 

[TwoTankAmin]

OK this is the best I can do to show that alga do indeed feed on phosphorus. The paper investigates using algae to remove excessive P from water. Even more interesting is that for it to consume the maximum amount of P, something from the nitrogen complex must be added- nitrate being one possible facilitator. No this is not an aquarium related study but then I am only trying to show algae can and does take advantage of P to thrive and grow when given the opportunity.

The paper was for graduate thesis at the University of Utah in 2010. This is the abstract:

Abstract
The Logan City Environmental Department operates a facility that consists of 460 acres of fairly shallow lagoons (~ 5'deep) for biological wastewater treatment that meets targets for primary and secondary treatments (solids, biological oxygen demand (BOD), and pathogen removal). Significant natural algal growth occurs in these lagoons, which improves BOD removal through oxygenation and also facilitates N removal through volatilization as ammonia under high pH conditions created by algal growth. Phosphorus, however, is non-volatile and stays in the water and likely cycles in and out of algal cells as they grow and die in the lagoons. In the near future, the regulatory limits on phosphorus released from the Logan wastewater treatment facility are likely to become significantly lower to counter potential downstream eutrophication. One way to potentially lower phosphorus levels in the wastewater effluent is through management of algal growth in the lagoons. As mentioned above, algae growth naturally occurs in the treatment lagoons and if the algal biomass is harvested when growth yields are highest, the phosphorus contained in the cells could be removed to obtain phosphorus-free water. The algal biomass could then be used for production of biofuels. This research focuses on laboratory and pilot assessments to show the ability of algae indigenous to the Logan lagoons to uptake phosphorus and produce biomass that can be used for biofuel production.

The full paper can be found here Title Removal and Utilization of Wastewater Nutrients for Algae Biomass and Biofuels

My point in posting this is merely to show that in freshwater algae do indeed feed on P. So when one has a nutrient imbalance in a tank in relation to plant mass, light levels, co2 levels and nutrient levels, the likely outcome is algae growth.

 

[StandbySetting]

OK this is the best I can do to show that alga do indeed feed on phosphorus.

We never said they didn't feed on P, we were stating that it doesn't cause algae, cause and feed are two totally separate things.