# can you over fertilize?



## kittiekuddles

I was wondering if over fertilizing is possible and what the effects would be? like how would i know if im over fertilizing?


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## Tex Gal

This is an old question that opens many cans of worms. Some (like those using the EI method) believe that as long as you do weekly waterchanges to reset your tank you can't hurt anything even if you over fertilize. The key is to have plenty of CO2 and not too much light.

Others believe that any fertilizers more than the plants use is over fertlizing and causes algae. 

Do some reading in the fertilizing section on the different methods. I think it's a good place to start.

AND welcome to APC!


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## Philosophos

Sure, toxicity can happen. It sure isn't going to happen at the colins-sears ratio for macros or most micros. EI uses something similar. Check out what used to be used for testing aquatic plant growth:

KNO3: 1M 6.0mls N 224ppm
Ca(NO3)2*4H2O 1M 4.0mls K 235ppm
NH4H2PO4 1M 2.0mls Ca 160ppm
MgSO4*7H2O 1M 1.0mls P 62ppm
S 32ppm
Mg 24ppm

(Hoagland and Snyder, 1933)

KNO3 1M 5.0mls N 210 ppm
Ca(NO3)2*4H20 1M 5.0mls K 235 ppm
MgSO4*7H20 1M 2.0mls Ca 200 ppm
KH2PO4 1M 1.0mls P 31 ppm
S 64 ppm
Mg 48 ppm

Those sort of levels will kill all of your fish before your plants ever complain.

It's not much of a question as to whether high nutrient levels induce algae in and of them selves; they don't. Tanks have been kept with high nutrient levels and no real algae concern. By definition, this eliminates the claim.

The other variables would be the question; under what conditions do high nutrient levels cause alage? Right now the going answer would be high light, low CO2. Much of thebarrreport.com is an exercise in proper CO2 and light distribution. Many of the answers to newcomers looks like "turn your CO2 up."

I honestly haven't seen these principles fail yet under thorough examination. The issues tend to be secondary; cost and maintainance level are more frequently the problem. Both of these are understandable issues, and precisely why there are other methods that don't require as much fertilization or effort. Hybrid methods are sort of an inevitability of all of this, and still frequently enforce principles common from all sides.

Now the odd micro/trace nutrient would be the real toxicity issue. Cu is the most common; old pipes and medication are frequent causes. Others can happen as well, and frequently look like deficiencies. 

The easiest detection method is to know what's in your water column. If you know a nutrient isn't deficient in the column based on what's been dosed, but the plants look like they are, there are only a handful of possibilities. Most commonly, the issue is excess or toxicity of something else. Other issues can include the form of the nutrient, the dosing schedule, or the mixing and storage of the fertilizers. All of these shouldn't be an issue if using an established method.

-Philosophos


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## Zapins

Philosophos is right. Toxicity can and does happen, but more commonly it is deficiencies that happen more often.

Another problem is nutrient blocking, this usually happen when the ratio of nutrients is extremely exaggerated and the presence of one nutrient either blocks the uptake of another nutrient or destroys it. For example, if you have say 400 ppm Mg and only 10 ppm Ca you will most likely get Ca blocking because the plant receptors used to absorb Mg and Ca (and K) are being taken up by Mg all the time this results in Ca deficiency. The normal ratio is 3 or 4 Ca:1 Mg 

On the other hand if you have high phosphates you will decrease the concentration of iron in the water because they react in the water.


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## kittiekuddles

oh my, i am not as advanced as you guys  

but heres what im doing so far
29g
65 watt daylight bulb (power compact strip)
3" eco complete substrate
seachem root tabs (i ony used three tabs)
seachem flourish half cap twice a week
seachem excel half cap twice a week (i have vals so im afraid to dose too often)

plants are growing, but sometimes they look a little yellow. tank is also new, the plants are 3-4 weeks in the tank


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## Zapins

Sounds like a bit of a nitrogen deficiency, or possibly iron.


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## Philosophos

Ya, sounds like nitrate is showing first. Potassium holes followed by leaf tips stunting and dropping off along with a bout of BBA plus GSA would be the normal course of things. Perhaps not in that exact order.

Essentially what I'm saying is that with the light you've got, you're probably heading for full NPK deficiency. Ca and Mg will likely be lacking too. CO2 would be a big concern as well.

Start dosing for NPK, Ca, Mg. Use excel and a lot of DIY CO2, or more preferably compressed CO2.

Alternatively, reduce your light level to about 1-1.5wpg and still start dosing the macros lightly. It's that or head NPT with a substrate overhaul.

-Philosophos


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## Zapins

Yep, what Philosophos said, except you can just decrease the time the light is on per day instead of getting new lights. Put the lights on a timer for roughly 7 hours a day until you get the fertilizer situation figured out, then you can increase it slowly over the next two weeks back up to, say, 10 hours or so. Just make sure to add some kind of CO2 to the tank otherwise you will probably have problems every now and then.


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## Tonysopinion

I just did a 30% water change on my 65g tank.
I dosed all liquid macros and trace at once. Can this kill my fish


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## DutchMuch

nope
Wait how much did u dose, like the entire 500ml (example) bottle? or the recommended amount?


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## hoppycalif

Welcome to APC, Tony! What can happen when you dose iron and phosphates at the same time is that they combine to make iron phosphate, which won't dissolve in water. That becomes a precipitate, and isn't readily available to the plants. It isn't clear that this will happen with the very dilute mixtures that are in aquarium water, but it certainly does happen if you mix them up in a fertilizer bottle.

Here is one fertilizing method that many of us use: http://www.aquaticplantcentral.com/forumapc/fertilizing/15225-estimative-index-dosing-guide.html I suggest reading the first post, and perhaps some of the other fertilizing method descriptions, then adopting one of them to guide you.


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