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I'm dosing E/I in my 75 gal tank. But I have a problem with it that I don't understand. By the end of the week my phosphate is really high (10-20ppm)

My tapwater phospate is .05 ppm according to my AP test kit. Even underdosing by a little seems to jack it up there. I have been dosing 1/4 tsp on macro days. Even tried decreasing the amount by "not quite" filling the measuring spoon. I can't seem to find the smaller spoons either.

Now I realize that test kits aren't always accurate, but the test doesn't "kinda" max out, it gets there right away.

Any ideas on this? I typically feed once a day and I keep it limited in amount.

Do I dare just quit dosing PO4 and see what happens?
 

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my phosphate + nitrate are steadily increasing as well. not sure why. i have root tabs too. maybe that is why. i'm planning to do a 1/4 water change tomorrow and will not add fert excempt trace elements.
 

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Discussion Starter · #3 ·
I don't have any root tabs, just eco-complete.
 

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How high is the nitrate rising in relation to the phosphate. Phosphate tests are known to give false readings and if your phosphate is getting that high with a nitrate measurement of say 5-10ppm you should be having algae problems.
 

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I have seen no evidence that phosphate in abundance leads to algae. Too little phosphate can lead to GSA, but no one has shown that too much leads to any form of algae. That is one reason why it is safe to follow the EI dosing guidelines - the 50% water change once a week removes any excess of any fertilizer long before any problems would occur.
 

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Hoppy: Wouldn't an imbalance like 5 ppm nitrate to 20 ppm phosphates cause an issue? I know a high phosphate amount in relation to a balanced nitrate amount doesn't cause problems. In fact I've witnessed better coloration this way. That's why I questioned what the nitrate measurement was too.
 

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Hoppy: Wouldn't an imbalance like 5 ppm nitrate to 20 ppm phosphates cause an issue? I know a high phosphate amount in relation to a balanced nitrate amount doesn't cause problems. In fact I've witnessed better coloration this way. That's why I what the nitrate measurement too.
Anthony, Hoppy is correct, but so are you.
Hoppy is right in that there has been no evidence of PO4 abundance leading to algae....none, It was once thought that it did, but that is not the case.

However....

You are correct in the ratios being important, but the limiting factor is Nitrates....NO3 should be at a higher concentration than the PO4 optimally, but again, depending on the Carbon concentration, the plant only uses so much, so as long as you have enough, that is fine...excess is drained out when you do your water changes.
Same holds true for PO4...if you have excess, it simply will not be used, and will reset when you do your water change. That is the principle behind EI...even though your ratios aren't perfect, have enough of all that the plants need, and reset the parameters during your weekly water change. Testing is good for one reason if you dose EI. If you want to fine tune your regimen as to dose what you need so there is no excess....this is a long process and requires testing and watching your plants to see if there are noticible signs of deficiency over time. Again, EI eliminates the need, and the ferts themselves are not that expensive....your time taken to fine tune all of this is more prescious....so dose em up and take the tankwater from your waterchanges and water your terrestrials with it! They will apreciate it!
 

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I'm dosing E/I in my 75 gal tank. But I have a problem with it that I don't understand. By the end of the week my phosphate is really high (10-20ppm)

My tapwater phospate is .05 ppm according to my AP test kit. Even underdosing by a little seems to jack it up there. I have been dosing 1/4 tsp on macro days. Even tried decreasing the amount by "not quite" filling the measuring spoon. I can't seem to find the smaller spoons either.

Now I realize that test kits aren't always accurate, but the test doesn't "kinda" max out, it gets there right away.

Any ideas on this? I typically feed once a day and I keep it limited in amount.

Do I dare just quit dosing PO4 and see what happens?
doc doc

Many if not most home tests for PO4 stink IMO. You cannot rely on them to determine PO4 concentrations. IMO dose your EI and watch your plants...if it aint broke don't fix it.
My PO4 out of the tap is high here, and I still dose PO4...I don't have algae and my plants are flourishing....
 

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I don't dose any Nitrate at all and dose plenty of Phosphate in my 10 gallon. I find that the fish and shrimp poop provide enough nitrate and that excess phosphate has no ill effects on anything in the tank. In fact I have to feed the tank algae tabs in order to keep the otto's and RCS from starving.

IMO I wouldn't worry at all about the high test readings even if they are accurate...

-Ryan
 

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dipan....I know this all too well as I had this issue too...water changes over time allowed these levels to level off, but all told it never did anything other than show a high reading on my test kit...
I didn't have algae, fishdeath or plant growth stunting...so all told, keep doing water changes and it will level off.
 

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I realize that phospahtes arent the cause of algea in our plant tanks, but what about in non-planted tanks? When we have an imbalance and the phosphate is high, its usualy the lack of other nutrients to cause the algea, since without the other nutrients the plants cant take up the phosphates. But with no plants and no intention to keep things at any particular level, and one ended up with really high phosphates, would algea ensue? And would the level of phosphate have anything to do with it (ex, the same imblance of parameters, except the phoshpates are 0, would algea still result)? I havent really had a non-planted tank in a while so I am curious.
 

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Too much phosphates will trigger a bunch of algaes, like common fuzz. Too little will result in GSA as previously mentioned. How much is too much? It depends - on lights, fert ratio, CO2, plant mass, and fish load yadedada... If you don't have GSA, you probably have enuf PO4.
 

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To further my curiosity here... assuming one had a non-planted tank, and got GSA, would it be beneficial to then add phosphates even without plants? Or would the addition of phosphates only help against GSA in the presense of proper ratios of other ferts aloing with plants to suck em up? I havent had GSA in a long time (since I started EI atleast) but just curious what would happen in a non-plant tank. Guess I am just wondering because I had GSA pretty bad before I started doing the co2/fert/heavily planted tank. And there are still a ton of folks who use phosphate removers to rid themselves of algae in the low tech non-planted aquariums.
 
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