Iron versus High Light - Fertilizing - Aquatic Plant Central

Go Back   Aquatic Plant Central > Special Interest Forums > Fertilizing

Fertilizing Science of Aquatic Fertilizing - Discuss fertilizing techniques and proper aquatic plant nutrition here.

Reply
 
LinkBack Thread Tools Display Modes
Old 02-11-2005, 05:52 AM   #1 (permalink)
Senior Member
 
Freemann's Avatar
 
Join Date: Mar 2004
Location: Greece
Posts: 340
iTrader Ratings: 0
Freemann is a regular member
Default Iron versus High Light

Hello everyone

I have a 100 gal tank with 3 150 w, single ended metal halide bulbs with included UV protection, 4.200 k, 19 cm above water level, this are on for 12 hours daily (no additional glass for UV protection but the one offered by the lamp each self, whole fixture is enclosed in a wooden frame that blocks exposure of the room to UV).
In this tanks all ferts (Fe from EDTA currently, TE from flourish, KH2PO4 ,Ca(NO3)2, KH2SO4 are dosed with dosing pumps which keep the ferts at constant levels absolutely controllable ppm wise.
The substrate is pure fluorite with 1 cm peat mixed with mulm on the bottom of it. A 150 w Rena cable runs all along the first 1 cm bottom layer and it stays on 24 hours per day that keeps the substrate worm with the intension of transferring partial fertiliser to the bottom from the column through convention (possible acceleration of decaying of peat?). This tank has great fast growth of all plants including ones like macrandra, didiplis, eleocharis parvulus aromatica nasaea e.t.c. plant coverage is between medium to high. Measurements NO3, free Fe +2 - Fe+3, PO4 are done with a hanna colorimeter and K with a Hanna turbidometer so the readings are very precise. There is 2.500 lt circulation pump on it attached to a pair of lifeguard filters with 20 micron micro filters and a huge biological filter full of bioballs.
Sample testing values are:
NO3 7 ppm
Free Fe+3 FE+2 0,15 ppm
PO4 0,8 ppm
K 13 ppm
NO2 O
NH3 O
Kh 3
Mg to Ca ratio 1 to 20 (sudden high increase of Mg is triggering almost instantly new leaf curling in sensitive plants.

pH no current reading but there is ample CO2 almost 100 bpm all dissolved and plants bubble from hour one on light circle.

This tank has a constant problem of thread algae, BAG, Spot algae, algae seems to have a vigorous growth like the plants and needs to be cleaned daily to keep the plants "free" of it also the algae that settles down is removed daily with a siphon lately 10 % water changes (with RO currently to push the Gh and Kh down a bit) are done at the same time.
As far as I can observe all are in order. So some detective work is needed and I tell you after lots and lots of experimenting I am really frustrated. Increase of NO3 to 10 ppm or more (PO4 is always increased with NO3 in a ratio of 10 NO3 to 1 PO4) or a bit more will just increase the algae growth and at the same time the leaf size of all plants. Same goes for Iron the more I increase it the redder and more vigorous plant growth I get but also more algae (I can virtually nulify algae growth with a drastic decrease of Fe and I have tried this repeatedly but plants really suffer). The TE I keep stable dosing only 2,5 ml flourish daily.
Sensitive plants in the tanks to iron deficiency like parvulus and mayaca seem to excibit light green to white growth (Mayaca) also some curling is observed (from some effect of Fe to something according to my observations) when iron is reduced below or at 0,1 ppm, at 0,22 - 0,25 ppm of iron in the column all seem to be growing fine but algae increases really fast. I have tried both the iron gluconate and the iron EDTA. The approach with both irons is effective but still plants seem to be unable to cope with their iron demands in the amounts that algae will be kept at bay.

From my observations iron is probably the most catalytic fertiliser in growth behaviour in our plants.
But it seems that the amount of iron that is needed in the column with all this light to keep the plants happy (with no iron included in the substrate but only the fluorite, which I think is inert anyway), is a perfect algae inducer, grower as well.

From what I can read in Diana Walstad's book (one of the few people unfortunatelly for us that has done some serious experimenting):

Quote:
from pages 167 to 169 from The Ecology of the Planted Aquarium

Iron may be the limiting nutrient for algal growth in aquariums, if only because so many other nutrients (e.g., N and P) are so plentiful. Also, iron is the one nutrient that is required in fairly large quantities while being the least available in oxygenated water. Thus, I sometimes have problems with algae after setting up a tank with garden soil, because considerable iron is released into the water during the first two months (see page 131). Only after the soil has 'settled down', does the iron release stop and algal problems diminish.

a) Iron as the Limiting Nutrient for Algae

Iron's limited availability in oxygenated water sets iron apart from all other plant nutrients.3 This is because free iron (Fe2* and Fe3*), which is the only form that algae can use [28], doesn't ordinarily accumulate in the water. It either forms various iron precipitates (FeOOH, FeCO3, etc) or binds to dissolved organic carbon (DOC).
It is not surprising that most natural freshwaters contain only small amounts of iron, most of it bound to DOC. Indeed, the iron concentration of most oxygenated surface waters is less than 0.2 mg/1, and almost none is in the free form that algae (or plants) can use [26]. Hard water lakes, in particular, may have little available iron. Thus, one investigator [29] found algal growth to be limited by iron in several natural lakes. For example, phytoplankton cultures from Lake Ta-hoe (U.S.) were greatly stimulated by adding as little as 0.005 ppm Fe.
Enormous areas of open ocean have limited algal growth despite relatively high nitrate and phosphate levels. Because these areas are far removed from terrestrial sources of iron (e.g., soil dust), iron is present in exceedingly small amounts, less than 0.000056 ppm. Thus, when investigators added iron to experimental bottles containing these algae and their natural ocean water, algal growth was stimulated [30].
My point is that because iron doesn't stay around very long in oxygenated water, it can limit algal growthin aquariums as well as oceans. Unlike phosphate and other plant nutrients, which can and often do accumulate in aquarium water, the reservoir of free iron in aquarium water is limited.

b) How Algae Gets Iron

Plants can get their iron from the substrate, but algae depend on free iron (Fe2* and Fe3*) in the water. Although iron in the water is indeed bound up, often to dissolved organic carbon, it is made transiently available by a common process called the 'photoreduction of iron'. The reaction for the photoreduction of DOC-bound iron is:
DOC-Fe3+ + light => Fe2+ + oxidized DOC
This light-requiring reaction, which also applies to manganese and copper, is greatly accelerated by DOC (my note: here DOC comes in the equation as well) [31,32,33]. The photoreduction of DOC-bound iron is invariably accompanied by the decomposition of DOC (see page 59).4 The Fe2+ released may be taken up by algae or quickly oxidized to Fe3+, which can also be taken up by algae or bind to fresh DOC, whereby the process repeats itself.
Different investigators demonstrated iron photoreduction using a variety of light sources ('Cool-white', 'Daylight', and Vita-Lite fluorescent bulbs as well as sunlight). However, UV and blue light induce the most photoreduction, because only wavelengths below about 500 nm are energetic enough to break the chemical bonds [31].5 Thus, investigators showed that only wavelengths below 520 nm released free iron from one DOC-chelated iron (Figure X-l). Algae grew well under normal light with chelated iron as the only iron source, but when light wavelengths below 520 nm (my note can that be a factor cause I do not use additional UV filter?) were filtered out, the same algae became iron deficient and would not grow.

Iron is bound to a variety of chemicals and different types of DOC. These iron complexes all have their own peculiar 'iron-binding tightness' and susceptibility to both photoreduction and chemical reduction [34], Thus, algae may, indeed, have access to some iron even in the dark. However, algae will get a far larger supply in the presence of light and DOC. Thus, Fe'~ levels in one lake were found to be almost 5 fold higher at midday when light intensity was greatest than at night [31] In natural systems (and aquariums) the photoreduction of DOC-bound iron is probably essential to supplying algae with iron.

Aquatic plants readily take up iron directly from the water [35], even when planted in iron-containing substrates [36,37]. For example, iron uptake by Hydrilla planted in a peat substrate was shown to actually equal iron precipitation as a means of removing iron from oxygenated water [36]. Plants would continuously drain free iron (Fe2+ and Fe3^) from aquarium water, thereby depriving algae of a much-needed nutrient.
In aquariums containing soil under layers, fertilization with chelated iron is almost surely unnecessary. Soils have enormous quantities of iron (see page 83). Not only do they contain plentiful iron, but also the anaerobic conditions that keep some iron in the free, unbound form that plants can use.
In my opinion, the substrate- not the water- is the primary place to provide plants with iron. Recommendations to maintain a certain water level of iron may be based on work that doesn't apply to the home aquarium. For example, aquatic botanists and hydroponic growers routinely add EDTA-chelated iron, but their plants may be sterilized beforehand or grown emergent. Under these circumstances, chelated iron is essential and won't promote algae. But what is appropriate for aquatic botanists and hydroponic growers is not always appropriate for the home aquarist. (my bold]
Also is it a coincidence that the Dupla guys always used gravel mixed with lots of Laterite in their substrates?
So I was wondering has anyone observed similar problems or has some thoughts on the subject?
Sorry for the long post

Freemann

Last edited by Freemann; 02-12-2005 at 03:07 PM..
Freemann is offline   Reply With Quote

Advertisement [Remove Advertisement]
Old 02-11-2005, 06:58 AM   #2 (permalink)
Senior Member
 
Join Date: May 2004
Location: Brooklyn, New York
Posts: 1,035
iTrader Ratings: 3
iTrader Positive Rating: 100%
pineapple is a regular member
Default

Yours is an eloquent description that deserves thoughtful responses. My offering is, for sure, too succinct and does not even address your topic of Fe. I had a similar situation and found that the missing element was K. K2SO4 dosing resulted in almost immediate decrease of algae and the total demise of thread algae. Previously, thread algae had come instantly with dosing Tropica and Fe (in very soft water). I dose large amounts of TE and Fe now without thread algae. Just learning by my mistakes here...

I leave the subject to others...

Andrew Cribb
pineapple is offline   Reply With Quote
Old 02-12-2005, 03:52 AM   #3 (permalink)
 
Join Date: Sep 2004
Posts: 60
iTrader Ratings: 0
aviel is a regular member
Default

Hi,

Diane Walstad talks about co2 limited tanks where growth and plants demand is very limited compared to your high tech tank. When there's high growth iron fertilization in the substrate is probably not enough. I wouldn't starve the water column, u need to feed your plants in order for them to flourish and then algae shall disappear. I noticed that algae attaches to those plants that have poor growth so either I take care of their needs or I toss them away. I was on the lean side with ~0.03 ppm per day of iron, and ~20 ppm CO2 - I experienced thread algae + BGA. Once I added CO2/iron - the thread algae went away. I really like to read Diane Walstad book and posts but when it comes to my tank I try to understand first if they are applicable or not.

One more thing that I don't understand is your UV setting. I use UV - it's not located above the water - it doesn't light the plants or the fish - the water going out from my canister filter flow through this pipe where they are exposed to the UV light.

Aviel.

Last edited by aviel; 02-12-2005 at 04:16 AM..
aviel is offline   Reply With Quote
 
Old 02-12-2005, 06:06 AM   #4 (permalink)
Senior Member
 
Freemann's Avatar
 
Join Date: Mar 2004
Location: Greece
Posts: 340
iTrader Ratings: 0
Freemann is a regular member
Default

Quote:
Diane Walstad talks about CO2 limited tanks where growth and plants demand is very limited compared to your high tech tank. When there's high growth iron fertilization in the substrate is probably not enough.
I never starved my plants on CO2. Co2 is in the range of 30 - 35 ppm here
I feed the plants iron from the column I say that aswell, plus the fact that I notice that the plants suffer when there is not enought iron in the column, thing is that there is no iron at all on my substrate.
The fact that Walstad speaks of no CO2 injected tanks makes no difference in relation to the fact of where from preferably plants aquire their iron (roots or leaves) or the fact that if iron is aquired from the substrate then there will be no iron for the algae to use in the water column at least not that much. My problem is that enough iron on the column here brings algae.
I have no UV installation I speak of the UV emited from the MH lamps.
If you notice Walstad states that UV breaks DOC binded iron back into it's free form. And this is what I wonder that may be happening.

Last edited by Freemann; 02-12-2005 at 06:11 AM..
Freemann is offline   Reply With Quote
Old 02-12-2005, 07:42 AM   #5 (permalink)
 
Join Date: Dec 2004
Posts: 1,194
iTrader Ratings: 48
iTrader Positive Rating: 100%
chiahead is a regular member
Default

Freeman,
I will try to help although I am not very well versed or experienced. Dose your dosing happen all the time during the day? I dose right at lights out so that the light has no effect on breaking down the iron. I seem to think that at night the plants store the nutrients for use during the light period. I could be wrong here. From my experience I have better results when the plants take in the ferts when they are not photosynthisizing. As far as your substrate containing iron, Flourite does have iron in the complex form, I believe. You can supplement with clay balls. I do that, its easy and very cheap. I make my own out of red art clay mixed with some macros. I am not a chemist so I dont know why things work but I learn by trial and error. Some of the guys on here know alot about this, they should chime in.
chiahead is offline   Reply With Quote
Old 02-12-2005, 08:49 PM   #6 (permalink)
 
Join Date: Dec 2004
Posts: 1,194
iTrader Ratings: 48
iTrader Positive Rating: 100%
chiahead is a regular member
Default

bumpbumpbump
chiahead is offline   Reply With Quote
Old 02-12-2005, 10:51 PM   #7 (permalink)
 
Join Date: Sep 2004
Posts: 60
iTrader Ratings: 0
aviel is a regular member
Default

Quote:
Originally Posted by Freemann
I never starved my plants on CO2. Co2 is in the range of 30 - 35 ppm here
Who said your plants are starving for CO2??? I said you have a CO2 injected tank - unlike Walstad tanks and therefore not everything that you read in Walstad book applies to your routine. For example Walstad claim that plants prefer Ammonium over Nitrate - while this may be true plants will consume nitrate and ammonium. They prefer ammonium because it's available and when they are co2 limited they just save the energy that is required to convert nitrate to ammonium but with a CO2 tank they shall consume both.

Quote:
Originally Posted by Freemann
The fact that Walstad speaks of no CO2 injected tanks makes no difference in relation to the fact of where from preferably plants aquire their iron (roots or leaves)
Again - when the demand for iron is low such as in a co2 limited tank substrate fertilization may be enough however in a high co2 tank you should add iron to the water column.

Quote:
Originally Posted by Freemann
or the fact that if iron is aquired from the substrate then there will be no iron for the algae to use in the water column at least not that much.
Latest thoughts are that you can't starve the water column - algae needs much less iron than you think. Substrate iron fertilization on the other hand shall starve your plants.

Quote:
Originally Posted by Freemann

My problem is that enough iron on the column here brings algae.
What levels are u talking about? Hobbyists her dose 0.1-0.3 ppm per day and sometimes more with no algae issues. How are you sure that this is your problem?

Quote:
Originally Posted by Freemann

I have no UV installation I speak of the UV emited from the MH lamps.
If you notice Walstad states that UV breaks DOC binded iron back into it's free form. And this is what I wonder that may be happening.
No need for UV to break the chelates. Simple daylight can do the job. It's not a bad thing - it's good that the light breaks the chelate - otherwise the iron wouldn't become available. This doesn't apply to the gluconate form.

Aviel.
aviel is offline   Reply With Quote
Old 02-13-2005, 03:08 AM   #8 (permalink)
Senior Member
 
Freemann's Avatar
 
Join Date: Mar 2004
Location: Greece
Posts: 340
iTrader Ratings: 0
Freemann is a regular member
Default

chiahead
Quote:
I dose right at lights out so that the light has no effect on breaking down the iron.
Good point I have considered this myself in the past and add the iron at night

Aviel
Quote:
When there's high growth iron fertilization in the substrate is probably not enough. I wouldn't starve the water column, u need to feed your plants in order for them to flourish and then algae shall disappear.
Well here it does not, plants flourish so does algae. Anyway I agree with you and I say so

Freemann
Quote:
I can virtually nullify algae growth with a drastic decrease of Fe and I have tried this repeatedly but plants really suffer
Aviel
Quote:
For example Walstad claim that plants prefer Ammonium over Nitrate - while this may be true plants will consume nitrate and ammonium. They prefer ammonium because it's available and when they are co2 limited they just save the energy that is required to convert nitrate to ammonium but with a CO2 tank they shall consume both.
Yes they seem to prefer ammonium and I think in both no CO2 injected and CO2 injected, ammonium is consumed anyway (mostly from biological filtration).
Aviel
Quote:
Again - when the demand for iron is low such as in a co2 limited tank substrate fertilization may be enough however in a high co2 tank you should add iron to the water column.
I agree again and in my case plants prosper from the additional iron (still remember that iron is limited in the roots here) but algae does as well.

Aviel
Quote:
Latest thoughts are that you can't starve the water column - algae needs much less iron than you think. Substrate iron fertilization on the other hand shall starve your plants.
Yes you can I have done it countless times in my other tanks and tanks of friends. Algae needs prolly less iron but it surely needs some and when iron is low in the column plants suck it all. My lean water column tanks have no algae whatsoever. Never but only when I add more iron primarily. All are CO2 injected, I even inject CO2 to the ones I don't add ferts at all on the column, just CO2 and rich soil substrate. So I think this is a misconception.
Also why substrate iron fertilization will starve the plants, what makes you say this?
Quote:
What levels are u talking about? Hobbyists her dose 0.1-0.3 ppm per day and sometimes more with no algae issues. How are you sure that this is your problem?
My free Fe2+ Fe3+ readings for this tank through the colorimeter are between 0,1 and 0.25 ppm and the 0,25 amount seems to be the best for the iron hungry plants needs like mayaca. But algae seems to thrive in this amounts.
By the way tank is mature 14 months old.

What I am trying to say is that if iron or really most of it (some can be still injected in the column but to complement plant needs) was made available through the root system, plants would be in an advantage to algae in the sense that they would acquire iron from there roots where it can be processed from anaerobic reactions and be available to them but the algae would be iron limited in the water column.

Quote:
No need for UV to break the chelates. Simple daylight can do the job. It's not a bad thing - it's good that the light breaks the chelate - otherwise the iron wouldn't become available. This doesn't apply to the gluconate form.
I reckon that when DOC binded iron that was added yesterday for example will break again to free iron through the UV emitted by the lamps (dont forget that MH are well known for emitting increased UV) this would add to the free iron and increase the problem.

Anyway you or anyone else for that matter tell me one good reason that algae won't take advantage of the the constantly existing ferts on the column when nothing is limited including CO2, high light? Until know none of the texts I have read on this persuaded me that this is the case.

I realise that lots of our experts here use rich substrates with lots of bacteria additions on them from commercial products initially and fairly lean water column all the time (through big water changes as well to reset the column). The ones that do tanks for clients will have to do that anyway to keep maintenance and control at its lowest.
Isn't that the idea behind Amano soils as well (put the food under, maybe that is why he mostly trims and not severe the roots as well)? Maybe someone should ask him directly if the readings of the nutrients in the tanks columns in his books are real (very low), which would prove additionally my point.

By the way here are some photos of the tank:
http://users.forthnet.gr/pat/ekfrasi...tank/Page.html

Last edited by Freemann; 02-13-2005 at 03:10 PM..
Freemann is offline   Reply With Quote
Old 02-13-2005, 10:34 PM   #9 (permalink)
 
Join Date: May 2004
Posts: 123
iTrader Ratings: 0
gregwatson is a regular member
Default

Quote:
Originally Posted by aviel
What levels are u talking about? Hobbyists her dose 0.1-0.3 ppm per day and sometimes more with no algae issues. How are you sure that this is your problem?

Aviel makes very good observations ... for example, I routinely dose Iron at a level of 1.0 ppm and higher ...

Greg
gregwatson is offline   Reply With Quote
Old 02-14-2005, 12:39 AM   #10 (permalink)
 
Join Date: Feb 2005
Posts: 252
iTrader Ratings: 33
iTrader Positive Rating: 100%
WfxXx is a regular member
Default

Hello Freeman
New to the forum but not new to plant tanks.
If I may
For the amount of light you have on that tank, you are way under-dosing everything.
You need a more disciplined dosing regimen, the algae in the tank is telling you something is not right and it will not get any better until you get a handle on your dosing.

EI
Day1) 50%H20 change, dose 1TspKN03/ 1/4TspKH2P04/ 1/4TspK2S04
Day2) Dose Trace 15ml/ 2to 3ml Iron
Day3) Dose mAcro's again 1TspKN03/ 1/4TspKH2P04/ 1/4TspK2S04
Day4) Same as day2
Day5) Same as day3
Day6)Same as day2
Day7) Re-set 50%H20 change, dose 1TspKN03/ 1/4TspKH2P04/ 1/4TspK2S04

You may or may not have to tweak amounts here and there to suit your tanks needs depending on what you are growing, how heavy planted the tank is, fish load etc. by adjusting the amounts, but not the frequency in which you dose, be dilligent and disciplined

Algae is growing because plant growth is slow, to stop the algae, you must increase plant growth.
With C02 in the 30 to 35ppm range with this schedule as a guide you will see a decrease in algae growth,and an increase in plant growth, you do need to manually remove as much of the algae as possible.

Plantex CSM+B 1lb. Price: $8.59------Mix 1Tbsp per 250ml H20
KN03 Potassium Nitrate 1lb. Price: $2.17
KH2P04 Mono Potassium Phosphate 1lb. Price: $3.42
K2S04 Potassium Sulfate 1lb. Price: $2.17
Iron Chelate Price: $8.59 -----Mix 1Tbsp per 250ml H20
http://www.gregwatson.com/products.asp?cat=8

Thanks

Last edited by WfxXx; 02-14-2005 at 12:44 AM..
WfxXx is offline   Reply With Quote
Reply


Aquatic Plant Central > Special Interest Forums > Fertilizing > Iron versus High Light

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Aquatic Plant Forum Replies Last Post
low light plants in high light areas? Dave B Aquascaping 11 09-12-2020 02:46 AM
10,000 kelvin bulb for good sidegrowth? Hanzo Lighting 31 04-29-2007 11:40 AM
Extremely High Light ShaneSmith General Aquarium Plants Discussions 9 11-30-2004 12:47 PM
Problem with Anubias in high light Hanzo General Aquarium Plants Discussions 5 05-21-2004 04:09 PM
High GH & Iron??? Nick D Fertilizing 2 04-22-2004 04:08 PM


All times are GMT -8. The time now is 11:14 AM.

Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

Search Engine Friendly URLs by vBSEO 3.6.1