# Don't use liquid fertilizers for plants



## Nahid_Siddiqui

There is a wide collection of liquid fertilizers for aquarium plants on the market. Very confidently they put on there label the following detail: "Does not promote algae growth". This is not correct and is misleading. They seem to justify this by saying the liquid fertilizer does not contain nitrates and phosphates which pollutes water and promotes algae growth. But we all know that nitrates and phosphates are also vital to plants and these are not the only contributing factors to algae growth. In-fact since the liquid fertilizer is to mix with the water it itself may be the contributing factor to algae growth since algae also need the nutrients plants need to survive and grow. As per Diana Walstad suggests in her book too much iron in the water can promote algae growth.

In my opinion the best option would be to somehow store the nutrients in the soil/substrate rather than to allow it to be mixed in the water!!


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## Zapins

Soil substrates are certainly one train of thought, though others work equally as well if not better (even though they require more maintenance to prevent algae).

I too wonder how fertilizer companies justify that statement about not promoting algae growth. If the fertilizer contains any nutrients algae use then technically it is possible that it promotes the growth of algae. Perhaps they get around this technicality since algae and plants can only grow as fast as the limiting nutrient supply, and in most cases the limiting nutrient supply is phosphate (and nitrates) in aquatic systems, so by not supplying the limiting nutrient they aren't promoting more growth. Though if this is the case one has to ask oneself why use the fertilizer at all if it isn't promoting growth?


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## Yo-han

I think that if it is possible to use the fertilizer without having algae (issues) they proved it. If someone else uses it with algae problems, the problem need to be something else. The only nutrient I know so far that promotes algae is ammonia (commonly used as nitrogen source for emersed fertilizer), iron is certainly not! But I think 99% of the commercially available fertilizers can be used without inducing algae if all other things are sufficient.


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## K Randall

Yo-han said:


> I think that if it is possible to use the fertilizer without having algae (issues) they proved it. If someone else uses it with algae problems, the problem need to be something else. The only nutrient I know so far that promotes algae is ammonia (commonly used as nitrogen source for emersed fertilizer), iron is certainly not! Bbt I think 99% of the commercially available fertilizers can be used without inducing algae if all other things are sufficient.


Phosphate out of balance with nitrogen is just as bad as too much nitrogen. But other than that, I agree completely. i have been successfully using liquid ferilizers for more than twenty years. I have had just as many or more problems with enriched (soil) substrates as I have with ferts added to the water column. My experience is that both systems work, but you need to pay attention.

The problem with systems that depend on the substrate (and maybe fish food) as the ONLY sources of nutrients is that unless you have VERY slow growth, eventually the nutrients in the substrate are used up, and the tank needs to be re-set. I have a tank that has been running, with excellent growth for almost 20 years now without EVER changing the substrate. It has a high CEC substrate, and has been fertilized regularly through the water column. MAYBE it's possible to do that with a soil substrate/fishfood tank, but I have yet to see one.


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## JEilerts

I, too, like liquid ferts. I use root tabs for my really hungry rooted plants, but for the everyday feeding, a good macro and micro seem to be best provided (for me) by liquid ferts.


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## phoenixkiller

I like mixing a solution of dry fertilizers in with some water, and injecting it into the water column. Haven't had a problem with it, and I'll be starting my 3rd planted tank using it as well.

I have heard my share of horror stories of dosing liquid ferts from Seachem and becoming an algae farmer. They are also quite expensive, at least in the long run, so I try to shy away from them as best I can.


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## Diana K

Ammonia does not promote algae growth any more or less than any other form of nitrogen. 

Most aquariums are low in carbon in a form that plants can use. This is usually the trigger that allows algae to grow. 
The balance of other nutrients (or lack of balance) probably tells you WHICH algae will grow. 

High nutrient level in the water in balance with carbon and the lighting can grow great plants with a minimum of algae problems. 

Plants can take in nutrients through the leaves and through the roots. 
In studies where the plant is in a split system, roots in substrate and water and the stem and leaves in a different water, the scientist can vary the levels of fertilizer in each container, and most plants do just fine taking in most nutrients from either location. But when you put plenty of a nutrient in both places the plants will selectively take in certain nutrients via the roots, and certain nutrients via the leaves.
Based on these experiments I try to keep root tablets and water column dosing going in my tanks. Hopefully the plants are taking in the nutrients they need in the most energy efficient way.


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## Nahid_Siddiqui

Hi Diana,

Thanks for your help. You know when you said plants selectively absorb nutrients based on whether its the roots in the substrate or the leaves, wont this result in some of the nutrients thus being free in the water, being used by the algae? As per the book by Diana walstad, she suggests that free iron and dissolved organic carbon in the water can promote algae growth. 

It seems that using carbon based filters and fast growing plants can counter green water problem to some degree but there is always the problem of plants selectively absorbing nutrients. I think these lead to filament algae What do you think?


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## houseofcards

Nahid_Siddiqui said:


> ...In my opinion the best option would be to somehow store the nutrients in the soil/substrate rather than to allow it to be mixed in the water!!


So what is your recommendation for feeding plants without root systems?


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## Nahid_Siddiqui

I think in that case we would need to assess what nutrients and how much of these nutrients these plants absorb and then add only that much. Obviously these would depend on what is the size of the plants and how much volume they have acquired. But to be honest I am not sure whether this ideal situation could exist because you can never make the plants absorb the nutrients efficiently and thus this will result in excess nutrients in the water. At the moment it seems CO2 works better for plant growth than nutrients and I am having a lot of trouble with riccia fluitans cause they seem to accumulate filament algae quickly. So I was actually wondering anyone else could give me a good suggestion.


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## niko

Nahid,

Go and find information about how ADA runs their tanks. All your questions will be answered.

What ADA does is not their invention. It is borrowed knowledge - practically proven.

Also - do not trust any claim written about a product sold for planted tanks. If you understand how it all works you can find an application for some products. But do not use the product packaging as a reliable guideline for anything.


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## fletch616

CO2..potting soil..and high lights! Best plants ive grown with this setup! No liquid! I used to use all the liquid..stopped and then went with potting soil!


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