Nutrient Info

S

Sumpin'fishy

Humble Disciple of Jesus Christ
Oct 16, 2002
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Savannah, GA
I picked up a book yesterday, and I'm very impressed with it. It's called "Encyclopedia of Aquarium Plants" by Peter Hiscock. It is copywrighted for 2003, so this must be a new one.

Anyways, this book really went into some great detail on many areas of aquatic plants and I was impressed to see them talk about CO2 systems, U/V sterilization and how it isn't normally good for planted tanks, specific nutrient info, and a detailed plant index, as well! My question stems from the nutrient information I read here. I have been told to pick up some Epsom Salt (Mg) because that was a necessary nutrient that is sometimes deplete. I did get some and added it (1/4 tsp for my 20 gallon) last weekend- no problems yet. This book has got me thinking about things, though......uh oh, don't do that!:rolleyes:

The book said that an excess of Mg in the water will inhibit uptake of certain other nutrients, specifically Potassium. It said that Potassium deficiency is usually due, in fact, to an excess of Magnesium! That is contrary to what I've been reading here.....or at least contrary to what I've been UNDERSTANDING from these boards. I have been dosing K for 2 weeks now, and dosing WELL. I use Flourish K and also KNO3. I have no idea what my tap water normally has in it, so I followed advice on the net and dosed enough Flourish K to get 20ppm (1/wk), then I add whatever amount of KNO3 I need to get my NO3 right (1/4 tsp-as needed), which adds more K. I also use Flourish (1ml 3x/wk), Flourish Fe (5ml 3x/wk, and Enema (10 drops 3x/week=1.0ppm). Phosphate is used up quickly in my tank! Also I have a standard 20 gallon using 70 wpg (40w NO FL/ 30 CFL "screw in")

Am I adding too much of something? Should I stop dosing Mg for now? I hear that Mg deficiency can stop Fe uptake. Do I just need to break down and buy (ANOTHER) test kit for Mg? Is this book even right? I thought I had things figured out, but this Mg and also a Ca question are haunting me. Which reminds me.....Do I get enough Ca from the Flourish and 1/4 tsp of Crushed Coral in the filter?
 
WetMan and a few others have made the case both here and (maybe more so) at Aquabotanic for "competition" between chemicals for uptake by plants. Seems many chemicals use the same pathways but some uptake more easily and can block out the others.

Not being entirely square with my chemistry, I'm still sorting this out.

I think the more commonly discussed scenario is phosphates blocking potassium uptake. You might want to look at your phosphate regimen and read up on PMDD (at least to digest the theory of it, which involves this uptake issue).

Epsom salts replace the GH components Ca and Mg (both, I think) when they are low or depleted, I wouldn't just dose it as a matter of course but only when needed to reach a target GH.
 
I've had Mg and K levels in the 50ppm range. This is far more than recommended ranges and I saw no issues with this in any plant or tank I had.
Nor have others.

So do you believe what they say? Does it match your observations?
I have not seen any practical evidence that UV's are bad for plant tanks.
I've never noticed that they have much effect on the system but I run mine if I use one for 1 day only after the weekly water change. There's no need to run them all the time. but when I have it did not seem to harm anything and I've done this many times.

I have not heard that CO2 is bad for plants. Plants are CO2 limited in water, adding more will help them grow. Plants are over 40% carbon by dry weight, adding CO2 is the largest single thing you can do to increase plant growth. This is common knowledge both in science and in the hobby.

Well growing plants= no algae issues.
So give the things that plants need to grow.

Regards,
Tom Barr
 
Thanks for the input Plantbrain. I'm glad you haven't had any issues with over dosing those nutrients. As for the U/V....I don't have one anyways, I was just repeating what the book, and a few articles I've read lately have stated. Something about how it chelates certain nutrients (maybe doesn't allow it to be chelated?) - can't remember. My point was that the book was touching on current debates and ideas. Most other books I read have outdated (older) methods they are discussing.....although many are still very useful.

Also, I skimmed back over the post and didn't see any reference to CO2 being bad. Am I missing something? I use DIY CO2 and recently upped the amount I use to get my dissolved amounts higher. Don't know what you were refering to there....:confused:

Thanks for the practical application experience. I'm sure it's very on par, as usual!
 
Originally posted by Sumpin'fishy
.
I was impressed to see them talk about CO2 systems, U/V sterilization and how it isn't normally good for planted tanks,
Click to expand...

I had to read it twice myself. It does at first sight look like you are referring to both U/V and CO2. After reading it twice, I realized it was only U/V that "isn't normally good..."
 
It's not really a case anyone has to make, it's so well known-- that both Mg and K compete with Ca for uptake. Epsom salts is magnesiurm sulfate. It contains no calcium. I wouldn't add it unless I knew that the calcium to magnesium ratio in my own water was unusually high.

Why? Because the question is one of proportions of Ca to Mg. You can pump up Mg and K levels as Tom Barr does without suffering any consequences, if you also have plenty of calcium in your water, as he does. However, if your calcium is low, you can induce symptoms of calcium deficiency by overdosing magnesium (with Epsom salts for example) or with potassium.

This is not an issue-- unless you have lightly buffered water.

Now, in Savannah GA you already have 6.5mg/lsulfate in your water. And your total dissolved solids average 160 ppm. I just checked at the city government site. Personally, I'd say you don't need Epsom salts. But I wouldn't have said that without looking at your water first.
 
"Anyways, this book really went into some great detail on many areas of aquatic plants and I was impressed to see them talk about CO2 systems, U/V sterilization and how it isn't normally good for planted tanks, specific nutrient info, and a detailed plant index, as well!"

I think I read this part as _including_ CO2 systems as well. I think it is seperate from the UV part.

The high energy UV light can break chelators releasing the iron from the complex and removing it from the water column.
It does happen in theory but I've not seen any practical evidence in any tank yet.

The inhibition idea about K and Mg sounds like the person found agricultural references of terrestrial plant biology rather than really seeing if this existin aquariums. Comparing apples to oranges and spreading myth.

Folks need to be careful when they cite things to make certain folks don't read this as fact, that it "might happen", "it's possible", "in terrestrial plants", " under these conditions" etc.

Applying northern deep lake limnology with virtually no plants to small shallow tropical densely planted aquariums is not a good comparision.

Be careful as to what you read into.
Also make sure you keep the CO2 / non CO2 type tanks seperated.

Diana Walstad has a evry good book for non CO2 tanks. I've found some interesting info on this side of the planted tank but it's a very sound book. Just make sure to read the parts that say "in this study", "for this plant", "this is what they found ".

Experiments and research are very specific. Folks need to be careful when generalizing and backing their arguments up in a book on general plant keeping. Some things matter, other things send folks down a wild goose chase for many years, decades.

Practical experience + science is a good approach. If they have not tried it, then I get a little worried about them when they say these things but I have and did not see any indication of their claims.

This makes me careful not to do the same mistake nor assume too much about a particular study.

Don't worry it might be a couple of years or so, but I'll get around to writing a book.


Regards,
Tom Barr
 
Thanks again, Tom. That is the whole reason I brought up these issues on this thread.....they sounded suspect to me. I was falling for the U/V thing, since it was stated (in the articles- more than one) that this was fact. The nutrient issues is my new "classroom" and I'm really enjoying my plant challenges. My first planted tank is teaching me alot.

I'd buy that book! Just as a suggestion....you might want to start cataloging different threads and questions you see, since it might be a neat idea to incorporate a frequently asked questions area into each chapter. I know you can answer many questions in the body of the writing itself, but some people may relate better to specific question. Especially since you know all the "scientific" answers and big words! You do pretty good on answering these posts though.
 
The inhibition idea about K and Mg sounds like the person found agricultural references of terrestrial plant biology rather than really seeing if this exists in aquariums. Comparing apples to oranges and spreading myth.

To limit the scope of misunderstanding:

1. All plant uptake of minerals is in the form of ions dissolved in water. Apparent exceptions, such as nitrogen fixation or agricultural dusting with sulfur, are misleading. Of course we are not talking about carbon uptake, whether diffused from the atmosphere or dissolved in water.

2. All nutrients are assimilated within the cells. (We are talking about plants, not fungi, etc.)

3. Nutrient uptake concerns the passage of ions through the cell membrane.

4. Whether the solution is pore water in the soil that bathes every root hair in a film of water, or a hydroponic solution, or aquarium water is immaterial: the actual uptake is local, at the cell surface.

Does anyone imagine that Anubias, Cryptocoryne or Echinodorus are affected or not affected by nutrient competition as seasonal waters rise or fall? These water plants are all angiosperms, as are orchard trees. An apple tree takes up no nutrient that is not in solution, not even from a dried foliar spray.

The competition between nutrients is well established in animals too.

I am merely a well-read amateur. Tom Barr has recently completed a course in plant physiology. Interested members might try a search at www.google.com , such as "plant+physiology nutrient competition calcium magnesium" Give it a try.
 
WetMan,

I specifically stated in the tanks I've dealt with and played around with all sorts of combination specifically with planted aquariums, this notion has no significant effects at the elves mentioned. These levels will seldom ....if ever... be exceeded by an aquarist. So much so that unless the GH is very high and they dose loads of K2SO4/KCl, it's extremely unlikely this occurs.

You can show semi relevant searchs with some of the same phases and words but it needs to be specific. Are marine phytoplankton algae that live 125 m the same as red epiphytic FW algae living in an acid stream at 0.25m?

Are all plants the same? How much generalization can one make about a study etc?

As far as dry nutrients or nutrients not in solution: are there any dry aquatic plant tanks? Not likely. Most tanks have the water part and plants can get nutrients from both the water column and the substrate.

We can add nutrients and maintain a relativityly stable nutrient content so that competition is reduced.

I know the terrestrial plant metabolism pretty well, it's not the same environment.
But you can try to see if you can show this in a planted tank.
Try varying the levels of Ca, K, Mg around and see what you find.
I did not find much.

It's a bit like Dupla saying P causes algae etc in a CO2 enriched high light tank.
We know it's not true now but when I started saying before, everyone thought I was nuts.

I just say what I see. I try and figure it out later.
See if anything might explain what might be causing this. Also finding out what it is not.

Regards,
Tom Barr
 
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