What macronutrient is most critical?
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What macronutrient is most critical?

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What macronutrient is most critical?
Old 04-17-2011, 04:54 PM   #1
 
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What macronutrient is most critical?

What's the most often lacking macronutrient? I'd like to dial in my plant fertilization routine. Currently, I have an ecocomplete substrate and dose 2x/week with Flourish comprehensive. I accidentally dosed 3x one week and noticed significant growth improvement. To me, that indicates I'm lacking something. I know my tapwater water is very low in iron, and moderately hard (about 80?).
My ammonia, nitrates, and nitrites all read 0 using the API kit. I'd rather not buy a test kit for each macronutrient.

As I experiement, which macronutrient should I try boosting first? Iron, potassium, phosphorus, or nitrogen? Any risk to the fish?
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Old 04-17-2011, 08:40 PM   #2
 
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To answer your last question first, yes. Some nutrients are also known as heavy metals (iron, copper, zinc, nickel, manganese) and it is worth noting that almost all water conditioners on the market detoxify these, for good reason. The level usually allowed in municipal water supplies may be "safe" for humans, but it can be lethal for fish and plants. For instance, copper is considered safe for humans at 1.3 ppm, but at concentrations as low as 0.02 ppm it can kill fish (some fish are more affected than others, and fry especially). And water conditioners are intended to handle "trace amounts" of these. Now, of course with plants in an aquarium, and provided the heavy metals are within the "safe" human level, plants will detoxify these as easily as a water conditioner--up to a point. But the main point is that in excess they are detrimental to all life--bacterial, fish, plant, humans.

The next point is that some nutrients when in excess can affect plants by causing them to shut down assimilation of some other nutrient. There are several. An excess of potassium can cause an iron depletion, as can excesses of copper, zinc and manganese. An excess of magnesium can cause plants to develop transparencies between the veins; I unfortunately experienced this first hand. The proportion of nutrients is complex, which is why the EI method advocates dosing certain nutrients and then doing large water changes to dilute them. I've never really comprehended the logic in that, but I understand the thinking that it ensures plenty of everything so the plants can experience the most growth. I still say the risk does not justify such waste.

Taking your initial question, all 17 nutrients are required for specific functions. Considering macro-nutrients: calcium, carbon, hydrogen, magnesium, nitrogen, oxygen, phosphorus, potassium and sulphur. Without any one of these, plant growth is hampered. Having more of any one will only result in additional growth if the others are already there, along with sufficient micro-nutrients [of which iron is one by the way]. Most of us try to keep it balanced, with light as the limiting factor; if light exceeds the available nutrients, algae is quick to take advantage.

Your example is interesting. Assuming you are not adding CO2 or using Excel, one would expect carbon to be your limiting factor. And there is no carbon in Flourish. It contains all nutrients except carbon, oxygen and hydrogen which normally occur in the aquarium. It doesn't have much of the macros, again because most water supplies have some of these (calcium, magnesium and sulphur), and phosphorus is normally sufficient from fish foods. It may be more likely that it is the micro-nutrients rather than the macro that resulted in the increased growth. Experimenting with Flourish Trace along with Flourish Comprehensive might provide an answer.

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Old 04-17-2011, 08:57 PM   #3
 
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Actually, I do use Flourish excel, but I don't think that invalidates the observation that it could be the micronutrients that are limiting. In fact, use of Excel might significantly exacerbate a micronutrient shortage. I'll see about getting some Flourish Trace (small bottle).

I agree that the EI method wastes fertilizer. On the other hand, most practitioners use dry ferts and the cost for those is ridiculously low, compared to liquid ferts, so they say. One reason I'm not anxious to try EI is the potential for overdoing it. In a perfect world, Seachem would make a multi-parameter "planted tank macronutrient" test kit. Something along the lines of the API master kit, just for different parameters. Now that would be nice (assuming it was reasonably priced)! Any aquarium product entrepreneurs out there?

Last edited by DKRST; 04-17-2011 at 09:03 PM..
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Old 04-17-2011, 09:07 PM   #4
 
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A quick follow up re: sulfur. Since Prime smells of sulfur (or hydrogen sulfide), does using Prime to condition the water add any residual sulfur to the tank?
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Old 04-18-2011, 06:40 PM   #5
 
Yep I through all the EI fertilizers in my tank and for both my 55gallon and 20 gallon it costs $30-40 every two years for all those fertilizers. Its the same as liquids, I can just make a bottle for 50 cents instead of buying it for the ridiculous price of around $10 a bottle. Even if I got away from high tech completely I would still use EI fertilizers where I need fertilizers. They would just last me half a decade lol, but hey you can make smoke bombs and rockets with some of them too...

As Byron has mentioned lack of or excess of certain nutrients can cause problems. EI is not immune to this either. All my plants are angry with me right now. High techs have been angry for a while for some reason I can't figure out, unless its the fact that I should stop eyeballing proper amount of dry fertilizers when I use them and actually follow the EI schedule like I use to... My 'el natural' tank joined in on the anger last week. I guess it had a good 5-6 month go before hitting a deficiency. I notice growth in stem plants becomes more inhibited then in crypts of anubias. The latter two get happier when my stems stop growing in all tanks. Sometimes you can confirm a deficiency with regular tests. My 'el natural' tank use to take the 20ppm from my tap to almost zero in a week with 50% waterchanges. Most recent test showed it was sitting at a little under 10ppm right before a water change. So along with visually noticing reduction in growth, you can sometimes confirm reduction of nutrient uptake. I'm familiar with some deficiencies, mainly potassium, nitrogen, and magnesium since I have dealt with those before. Usually there are signs in any deficiency in how the plants grow. All I know is all my stems are angry! Even H. polysperma.... My forest of crypts is taking over though...
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Old 04-18-2011, 08:24 PM   #6
 
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Right now, the plant issues I'm seeing are the following:
Ozelot sword -sending out new leaves, but the new leaves don't seem as "brown" as initial new growth was previously.
Corkscrew Val, gets about 5-8" and dies off from the end of the leaf, slowly browning (I suspect the Excel dose I'm using?)
American Val - growing much more slowly than after originally planted, some leaves are getting brown/dead areas in the middle of the leaf.

All my Swords are growing well, Rotalia is doing well, getting bushy but growth has slowed.
Purple Cabomba - just does not do well in my setup. Growing slowly, but not bushy.
Duckweed - killed off every darn bit somehow. Duckweed free right now.
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Old 04-18-2011, 08:51 PM   #7
 
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Quote:
Originally Posted by DKRST View Post
Right now, the plant issues I'm seeing are the following:
Ozelot sword -sending out new leaves, but the new leaves don't seem as "brown" as initial new growth was previously.
Corkscrew Val, gets about 5-8" and dies off from the end of the leaf, slowly browning (I suspect the Excel dose I'm using?)
American Val - growing much more slowly than after originally planted, some leaves are getting brown/dead areas in the middle of the leaf.

All my Swords are growing well, Rotalia is doing well, getting bushy but growth has slowed.
Purple Cabomba - just does not do well in my setup. Growing slowly, but not bushy.
Duckweed - killed off every darn bit somehow. Duckweed free right now.
Mikaila had some pertinent observation on plants changing due to this or that. Other members have noticed certain plants not doing well in tanks with certain other species, what is known as allelopathy.

Your Vallisneria may be due to the Excel. Enough planted tank aquarists have had Vallisneria species melt with Excel to make it an issue, even if not in everyone's tank; here again, different factors in different tanks can cause different things. But I would suggest Excel here. Unless you have soft water; Valls do much better in hard water. I have very soft water and my Corkscrew Vall grew exactly as you describe. I moved it to a new tank that is getting more magnesium and it seems to be a bit better, at least for now.

Most Echinodorus grow very pale new leaves that darken to green/red/brown depending over the first several days. However, in tanks with enriched substrates or higher liquid fert, they will be darker. I have noticed my Red Melon sword and the E. bleherae in the new Flourite substrate tank are producing somewhat darker leaves now from the first.

Purple Cabomba is a very difficult plant. I avoid such things, then I'm not throwing out dying plants.

Plants do go through cycles. They have growth cycles comparable to what they would experience in nature. I have noticed my swords slowing down then speeding up, thinking of new leaves, inflorescences, and such.

The aquarium is a very artificial environment for plants, and fish. No where in nature will you ever find the vast number of species of plants we cram into an aquarium. "Optimum" conditions are likely much more complex than we yet realize. Christel Kasselmann writes in her book about the lack of scientific study of habitats, and how we can sometimes get totally wrong ideas about plant growth. And of course, no plant in nature would ever grow as lushly as we "expect" it will in the aquarium. We are forcing the plants with light, nutrients, and we should feel pleased that most of them even grow.
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Old 04-18-2011, 09:23 PM   #8
 
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Smile

All excellent points from you both, and I appreciate it. This is the first serious planted tank I have ever tried. It's light-years beyond what I had in the 1980's and I am very pleased with results to date.

I guess the Echinodorus are always greener in someone else's tank!
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Old 04-18-2011, 10:08 PM   #9
 
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I guess the Echinodorus are always greener in someone else's tank!
Isn't that the truth?!!
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Old 04-19-2011, 12:24 AM   #10
 
Pictures would help a little. Going by what signs you mentioned, additives, and tank parameters. I would suspect nitrogen or potassium first. Though these are in Flourish comprehensive they are in small amounts. Both are macro nutrients. Given that your water has zero nitrates, which is something I try to avoid honestly. I would start with those two. I would also veer away from excel and suggest DIY CO2 if you wish to supply carbon. Excel is an extremely unnatural fertilizer, being a synthetic 'organic' compound that would never exist in nature. I have one bottle I bought a year ago that is used only for dealing with occasional really stubborn algae issues in my 55gallon. I can not even use excel in my smaller high tech tank, because the main plant species in there, subwassertang as I prefer to call it, hates the stuff more then any algae. That species is quite unusual and very simplest in structure, like algae in a way...

Byron made a good mention about plant cycles and the artificial environment we keep our plants in. I've seen plants do weird things I can not explain in the least. Red rubin swords for example last only 3-4 months in my 55 gallon before they are too big and blocking all the light. I bought and sold 4 of them because of this and just don't keep swords anymore, that is except one red rubin. Bought it together with another one both about 12" tall planted them in the same tank. The one took off like all the others before it. The other one shed all its leaves and has remained for over 6 months only like 2" tall. Its my only sword and its been all my tanks, currently in my soil tank. Nothing will make it grow, but its not entirely dead either.

Subwassertang is another good example of how little we know about some plant species. What it comes down to is basically, "hey it grows and looks nice, lets keep it". This particular species was kept in the hobby long before anyone figured out what it was. I've been growing if for 3 years and it was given its Latin name about 2 years ago. Its still quiet a mystery though. Vaguely similar to my post-diabetic kitty who is stealing my corn chips ATM.
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