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Feeding plants

Ingrid

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How often do you need to feed plant in a fish tank ?
 

Colin_T

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If you use an iron based fertiliser, you can monitor the iron level with an iron test kit and keep the iron level at 1mg/l (1ppm). If the iron level drops bellows 1ppm, you add a bit more fertiliser to bring the level back up to 1.

If you don't add fertiliser, then just feed the fish and give the plants some light and don't worry about it unless you get heaps of algae.
 

Byron

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This takes some explanation.

Plants grow by photosynthesizing. In order to photosynthesize, there has to be sufficient light (intensity and spectrum factor in) along with the necessary 17 nutrients in sufficient quantity to balance the light. And each species of plant has its own specific requirement for this balance; fast growing plants require more, slow-growing plants less, generally.

Light is thus the most crucial factor, as it must be of a certain intensity and spectrum to drive photosynthesis. Duration does not compensate for inadequate intensity/spectrum. So assuming the light is "OK," we can consider the nutrients which is the substance of your question.

Fish excrete all the nutrients plants need. There is also the breakdown of organics primarily in the substrate which adds more (especially the CO2). Water changes replenish the minerals (except obviously in very soft water) as well as removing substances that are detrimental to plants and others detrimental to fish. Depending upon the plant species and numbers, the light, and the fish load, some plants will manage very well just from the aforementioned.

If it is necessary to supplement any of these nutrients, it is important to do so with a balanced "fertilizer." An excess of some nutrients can cause plants to shut down assimilation of certain other nutrients; the excess can also feed algae because algae is not as fussy as higher plants over light and balanced nutrients. This is why comprehensive supplements are best; they provide what the plants need as a supplement to what will naturally occur in the aquarium, but the nutrients are in specific proportions to each other. Algae is much less likely to take advantage, because the plants are able to use what is being provided...again assuming everything is basically in balance.

Some plants benefit from substrate supplementation with products like Flourish Tabs as opposed to a liquid fertilizer. The real benefit here is that the plants can utilize the nutrients as needed while the nutrients are not just released into the water where algae may use them.

Comprehensive supplements include Seachem's Flourish Comprehensive Supplement for the Planted Aquarium, and Brightwell Aquatics' FlorinMulti. These are two I have looked into and used, but I'm sure they may be others. However, do not resort to individual nutrients; usually this is not going to benefit because it throws the balance out. The complete supplemental products contain what is needed in proportion as needed by plants, so unless you overdose (or under-dose), algae is not going to benefit.
 
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Ingrid

Ingrid

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This takes some explanation.

Plants grow by photosynthesizing. In order to photosynthesize, there has to be sufficient light (intensity and spectrum factor in) along with the necessary 17 nutrients in sufficient quantity to balance the light. And each species of plant has its own specific requirement for this balance; fast growing plants require more, slow-growing plants less, generally.

Light is thus the most crucial factor, as it must be of a certain intensity and spectrum to drive photosynthesis. Duration does not compensate for inadequate intensity/spectrum. So assuming the light is "OK," we can consider the nutrients which is the substance of your question.

Fish excrete all the nutrients plants need. There is also the breakdown of organics primarily in the substrate which adds more (especially the CO2). Water changes replenish the minerals (except obviously in very soft water) as well as removing substances that are detrimental to plants and others detrimental to fish. Depending upon the plant species and numbers, the light, and the fish load, some plants will manage very well just from the aforementioned.

If it is necessary to supplement any of these nutrients, it is important to do so with a balanced "fertilizer." An excess of some nutrients can cause plants to shut down assimilation of certain other nutrients; the excess can also feed algae because algae is not as fussy as higher plants over light and balanced nutrients. This is why comprehensive supplements are best; they provide what the plants need as a supplement to what will naturally occur in the aquarium, but the nutrients are in specific proportions to each other. Algae is much less likely to take advantage, because the plants are able to use what is being provided...again assuming everything is basically in balance.

Some plants benefit from substrate supplementation with products like Flourish Tabs as opposed to a liquid fertilizer. The real benefit here is that the plants can utilize the nutrients as needed while the nutrients are not just released into the water where algae may use them.

Comprehensive supplements include Seachem's Flourish Comprehensive Supplement for the Planted Aquarium, and Brightwell Aquatics' FlorinMulti. These are two I have looked into and used, but I'm sure they may be others. However, do not resort to individual nutrients; usually this is not going to benefit because it throws the balance out. The complete supplemental products contain what is needed in proportion as needed by plants, so unless you overdose (or under-dose), algae is not going to benefit.
That was very helpful and informative
 

Byron

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Thank you. I just realized I forgot an important aspect, and that is the impact of liquid fertilizers/additives on fish. While it may be necessary to use a comprehensive liquid (I do in all my tanks because substrate tabs are useless in providing nutrients to floating plants and those not rooted in the substrate) we must keep in mind that these do get inside the fish and keeping them minimal is important. Overdosing plant fertilizers, just as overdosing medicine, rarely benefits but usually makes things worse.
 

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If you use an iron based fertiliser, you can monitor the iron level with an iron test kit and keep the iron level at 1mg/l (1ppm). If the iron level drops bellows 1ppm, you add a bit more fertiliser to bring the level back up to 1.

If you don't add fertiliser, then just feed the fish and give the plants some light and don't worry about it unless you get heaps of algae.
I really like Colin's suggestion for when you don't use fertilizer. I have never had anything other than low light plants and following that advice have had my plants do reasonably well. Got to watch room light from windows though. You will see a couple pictures on these forums where algae really took over.
 

seangee

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To follow up on what @Byron said about liquid ferts. Many people on here (myself included) seem to do well at half the recommended dosage.
Personally I keep plants to benefit my fish rather than the other way around. For that reason I won't use CO2 or other substances that can harm my fish or shrimp (an example is the so called liquid Co2 which is actually poisonous, but great for plant growth). Different plants do have different requirements. If a particular plant plant fails to thrive in a tank I don't try to change it to suit the plant. I throw out the plant and plant something that does well in that tank. In my case that means different plants in different tanks because each tank is a unique, and different environment in terms of lighting, nutrients and CO2. And that means plants with modest light requirements, because all of my fish do best in subdued light.
 

Stan510

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I found Iron to be near a cure all for plants. I don't fertilize at all but I'm getting deep green lush growth when before it was just so- so to poor. I couldn't figure out why. I had the lights,the filter..but plants were not growing well..and I was getting far too much hair algae...just choking amounts in the 240 gallon that got window light besides over head.
I made the filter bigger..that helped. I covered the fine sands with normal sized aquarium gravels...that helped kill any residual blue green algae off. But what really did in bad algae was when I tried Seachem iron..all my plants flushed a deep green..plants that had died down to the rhizome have started to regrow. My Sword plant has just taken off fierce!..after a year of grow,dieback,grow,dieback. A Bolbitis heudelotii that I thought was a black goner...is sloooooowly reviving. My tap water must have been totally devoid of iron. I've dosed what the bottle says PER WEEK..since I feel like I'm feeding starving populations ...I might cut in half from this point..I have to just watch for results on that.
Its like I hooked up a Co2 system. Yet,all I Do is toss in capfuls per week. I know that since I've gotten great results...there is a much less costly iron for hydroponic and aquaponic sold at the Hydroponic stores ( or internet)..I have to try that next.
 

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So far I have not added any chemicals to my planted tank beyond de-chlorination and my plants are doing fine with the waste my fish produce-just don't add apple/mystery snails to your tank.
 

Byron

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I found Iron to be near a cure all for plants. I don't fertilize at all but I'm getting deep green lush growth when before it was just so- so to poor. I couldn't figure out why. I had the lights,the filter..but plants were not growing well..and I was getting far too much hair algae...just choking amounts in the 240 gallon that got window light besides over head.
I made the filter bigger..that helped. I covered the fine sands with normal sized aquarium gravels...that helped kill any residual blue green algae off. But what really did in bad algae was when I tried Seachem iron..all my plants flushed a deep green..plants that had died down to the rhizome have started to regrow. My Sword plant has just taken off fierce!..after a year of grow,dieback,grow,dieback. A Bolbitis heudelotii that I thought was a black goner...is sloooooowly reviving. My tap water must have been totally devoid of iron. I've dosed what the bottle says PER WEEK..since I feel like I'm feeding starving populations ...I might cut in half from this point..I have to just watch for results on that.
Its like I hooked up a Co2 system. Yet,all I Do is toss in capfuls per week. I know that since I've gotten great results...there is a much less costly iron for hydroponic and aquaponic sold at the Hydroponic stores ( or internet)..I have to try that next.
This could work in some situations, and I do not doubt you that it seems to be for you, but it is a dangerous method and frequently not successful. I have killed my floating plants by simply dosing too much iron. I did the experiment twice so I know it was the iron.

Plants need 17 nutrients, and in fairly specific proportions to each other. Excess of some nutrients--and iron is one of these--can cause plants to shut down assimilation of certain other nutrients. You would likely see better results still with a comprehensive supplement, which would contain iron in the right proportion. As you mention swords, the substrate tabs will greatly improve these plants.

The other thing is the fish and invertebrates; iron above what can all be used can cause issues.
 

Stan510

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True in a way. Anything overdosed causes harm. People with Co2,have had mass killings when a valve needle stuck,or the homemade bottle of gas turned into alcohol.
I think that gluconate that allows iron to be uptaken?..It must also help the plants take in other micronutrients that were there..just unavailable until now.
I should point out because sunlight is a big part of my lighting... I HAVE VERY DENSE growths of Vallisneria along with the Syngonium. I'm sure they can both absorb much more iron out of the water than the normally lit tank. It's almost pond like growth and you know what it would be like to to compare indoor vs outdoor plants. Since I have more fish than a typical plant centric aquarium,that pretty much is the fertilizer.
 

utahfish

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The two nutrients plants are usually deficient in are iron and potassium.
Of the 3 macro nutrients NPK potassium is the least problematic and also the nutrient plants need the most as NPK nitrogen phosphorous and potassium is about 7-1-10 ratio
Planted tanks should have around 20ppm nitrogen about 0.5 phosphates and between 20 and 200ppm. Of potassium.

Some good dry fertilizer sources of potassium are kn03 potassium nitrate which provides nitrogen and potassium and or k2s04 potassium sulfate, which excludes the nitrates.
Or one can as others have saud buy bottled liquid potassium or a comprehensive bottled liquid fert, most comprehensive ferts are high or should be in nitrates and potassium.

Second nutrient plants lack as has been said is Iron FE. One can buy pre made commercial liquid iron or dry ferts like iron ferrus gluconate are obe can fertilize the substrate with red clay balls, strips or laterite which will feed roots and leach into the water column.
Hope this helps good luck!

"Easy Green"is also a good comprehensive fert that as the title suggests is Easy to use.
 

Stan510

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Over the years,I have never added supplements...most plants did fine as I used to plant some in pots with potting soil under them with gravel on top ( I had undergravel filters back then). Some like Giant Hygro would grow well at first...then start to decline with those pinpoint holes in leaves. So,I can see adding potassium for them.
But,ferrous glutamate seems as I said,unlocks more than just iron.
In fact I went from 40% water changes per week...to 20-25% every two weeks. Plants and fish just seem the better for it.
The total lack of hair algae..something I struggled with..and blue green for a year and a half are both totally gone. Now,sunlight is a plus like I always thought it would-should be.
 
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