Confused about EI method and Iron PO4 interactions.
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Old 10-05-2013, 02:47 PM   #1
jonathan
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Confused about EI method and Iron PO4 interactions.


I working with a 29 gallon aquarium, high pressure co2, and dosing dry ferts.

I dont have all test test kits so I cant test for Iron.

But when I test for PO4 on micro days, its 0.05(edit) or sometimes barely readable. Is this because of Iron interactions or because I am possibly dosing too little ?

Today(micro day), I could not read any PO4 , so I dosed 1/16th tsp kh2po4 (I'll do a water change tomorrow anyway), and plants instantly started pearling. Dont know ...

Last edited by jonathan; 10-05-2013 at 07:31 PM.. Reason: missing words
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Old 10-05-2013, 05:29 PM   #2
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It could be a reaction although if you see no precipitation I doubt it. The dose sounds correct for your tank. I would make sure you are indeed dosing PO4. Then I would make sure you are performing the test correctly. I use an API test and the lowest reading,besides 0, is 0.25. That 0.005 reading is incredibly sensitive if that's the case. Try mixing some PO4 in R/O or distilled water and see what reading you get. If it's that low again it's not PO4 or the test is inaccurate.
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Old 10-05-2013, 05:50 PM   #3
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It could be a reaction although if you see no precipitation I doubt it. The dose sounds correct for your tank. I would make sure you are indeed dosing PO4. Then I would make sure you are performing the test correctly. I use an API test and the lowest reading,besides 0, is 0.25. That 0.005 reading is incredibly sensitive if that's the case. Try mixing some PO4 in R/O or distilled water and see what reading you get. If it's that low again it's not PO4 or the test is inaccurate.
Thank you for your response !

I'm sorry that was a typo. The test reads 0.05
The kit is made by ELOS.

What does precipitation look like ?
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Old 10-05-2013, 07:02 PM   #4
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What does precipitation look like ?
Sorry. Cloudy water or rarely small white particles that appear right after adding nutrients.

I have added micro and macros at the same time and never saw any precipitates. Although, they DO precipitate under the right conditions.
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Old 10-05-2013, 07:17 PM   #5
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Are you using a substrate with a high CEC? If so, maybe the PO4 is being absorbed by the substrate as well as the plants?
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Old 10-05-2013, 07:27 PM   #6
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Are you using a substrate with a high CEC? If so, maybe the PO4 is being absorbed by the substrate as well as the plants?
I'm using ADA aquasoil

Quote:
Originally Posted by Zorfox View Post
Sorry. Cloudy water or rarely small white particles that appear right after adding nutrients.

I have added micro and macros at the same time and never saw any precipitates. Although, they DO precipitate under the right conditions.
Interesting. I cant say I saw that. I will definitely be looking out.

Last edited by Darkblade48; 10-06-2013 at 04:22 AM.. Reason: Please use the edit function for back to back posts to keep threads cleaner
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Old 10-06-2013, 11:40 AM   #7
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Make sure you add your phosphates on different days to when you add your micros. The cab react causing a precipitate which will be less available to your plants and your test kit

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Old 10-06-2013, 12:15 PM   #8
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Make sure you add your phosphates on different days to when you add your micros. The cab react causing a precipitate which will be less available to your plants and your test kit

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They are on different days. What I am wondering is if phosphates remaining in the water column on micro ferts day interact with the iron and cancel each other out. If so, I'm not sure I understand how the EI method works in this scenario.
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Old 10-06-2013, 12:24 PM   #9
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No. Alternate days are fine. Even one in the morning and one in the evening is ok. Just not at the same time.

Its when one adds them at the same time, that the concentration of each in one area of the water can be high enough to react to a less soluble form which then dissolves slowly over time.

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Old 10-06-2013, 12:28 PM   #10
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I've dosed both on the same day and on different days and never noticed any difference in plant growth. One of the beauties of EI is not needing to test since the idea is to supply a nonlimiting amount of nutrients. If you want to test that's fine, but you end up chasing your tail when things like this come up. I think the concern with iron and PO4 precipitating is applicable to preparing concentrated solutions, not when dosing relatively miniscule amounts in your tank.

Last edited by Jeff5614; 10-06-2013 at 05:12 PM.. Reason: typo
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Old 10-06-2013, 01:47 PM   #11
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Exactly what I wanted to know. I think that means I need to increase my PO4 dose. Thank you.
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