# Rexolin APN staining my water



## Potatis (25 Jan 2013)

Hi, does anyone here use Rexolin APN for their micros? It's all I can get in Australia, it's similar to CSM+B, I believe. I'm having trouble with it staining my water dark yellow.

I dose according to the calculator at calc.petalphile.com and for my 300L tank I have been dosing 2.5g on Monday and Wednesdays. This gives me very yellowy orange water, which makes me sad.

I'm wondering if I can get away with a weaker dose, so it doesn't colour my water so much. 2.5g of Rexolin APN gives me:

Element	 ppm/degree
B				0.09
Cu			 0.02
Fe			 0.50
Mn			 0.20
Mo			 0.02
Zn			 0.11


I realise that the amount of 2.5g is to get the 0.5ppm of Iron, but I could dose that seperately. I wonder though if by cutting the dose, say in half, would give me too little of the other traces?

Thanks for any help.


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## ceg4048 (25 Jan 2013)

Hi,
   Sounds like you're using too much. 3 grams is almost half teaspoon which is about twice as much as you need. Cut the dosage in half and see how it goes.

Cheers,


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## Potatis (25 Jan 2013)

Ok, I'll try half. I've got a feeling the calculator is wrong for the Rexolin. Thanks.


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## ceg4048 (25 Jan 2013)

Well, maybe it is lower in Fe than CSM+B so maybe the author decided to increase the dosage, which would be OK except for the color problems. I try not to get too worked up about trace element mixes, because as I tried to explain to someone the other day, the plant takes up way more than it needs and these metals accumulate in the leaves. You know, that's why spinach is so good for you, because the leaves accumulate massive amounts of Fe, so the plant really only needs it for new leaves, which is not that much. Of course there's no problems have twice as much as you need but if you have issues like discoloration then that is not good. Maybe try a different brand of micros at the Garden Center. This can't be the only brand, surely...

Cheers,


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## dw1305 (25 Jan 2013)

Hi all,


ceg4048 said:


> Sounds like you're using too much. 3 grams is almost half teaspoon which is about twice as much as you need.


I'm with Clive on this it does seem a lot.

Is it this one?
Iron DTPA 6%;
Manganese EDTA 2.4%;
Boron 1.1% 
Zinc EDTA 1.3%;
Copper EDTA 0.25;
Molybdenum 0.25%;
Cobalt EDTA 0.03%

If it is have a look here: < RCS and APN micro mix [Archive]  - Aquarium Plants - Barr Report>

cheers Darrel


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## Potatis (26 Jan 2013)

Thanks for the replies.

Fe is a little lower in the Rexolin APN, but not much. Here is the comparison:

Plantex CSM+B (Composition in % by metric weight)
Fe = 6.53%
B = 1.18%
Cu = 0.09%
Mn = 1.87%
Mo = 0.05%
Zn = 0.37%
Mg = 1.4%

Rexolin APN (Composition in % by metric weight)
Fe = 6%
B = 1.1% or 0.85%
Cu = 0.25%
Mn = 2.4%
Mo = 0.25%
Zn = 1.3%
Co = 0.03%

Rexolin APN is a very fine brown powder, and the colour just dissolves straight into the water like food colouring. At the moment my water looks the colour of pee after eating multivitamins. The plants and fish are fine with it. Tomorrow I get to do my weekly water change, and the water will be nice and clear again. I'll dose half, which will weaken the colour, but I doubt it will be completely clear, it's fairly strong. The Wednesday dose adds to the Monday dose, which makes the colour darker. Perhaps I don't need a Wednesday dose if I can still see the colour from Monday?

I don't know of any other micro nutrients mix. There may be other trace mixes at garden centres, I haven't looked. I'd be worried that they wouldn't be safe for aquariums. Australians use Rexolin APN because that's all the suppliers sell, or pre-mixed stuff like Flourish Comprehensive which I used before I got my 300L tank. It's too expensive to use the Flourish on large tanks. I could try importing CSM+B if I can't solve this Rexolin APN colour issue. I'll see how the half dose looks tomorrow, and see if any deficiencies arise down the track.

Darrel, I have seen that link before, but I read it again. Nobody mentions a colour problem with the Rexolin, so all I can do is compare how much they dose compared to me, but just how much they are dosing is not clear to me. I need to compare whether 1 tbsp of Rexolin APN weighs 10g for me like it does for the person who made the last post. That may be a different weight to what the calculator uses, as it seems Wet needs to go by other people's say so, rather than weighing it himself.


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## Potatis (26 Jan 2013)

Ah, found this:  Micronutrient Source Comparison (inc Calculations)

Replies #7 & 13, it seems with a KH >3 there is yellow water. My KH is 5. I'm not sure of the science behind this.


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## ceg4048 (26 Jan 2013)

Archaeologists first discovered CSM+B in a garden center. Why would it be not safe to buy from there? Just look at the ingredients. It'll all be the same. You can also buy you NPK from there. I don't know why Australia has such tight controls on fertilizer. Are they trying to protect the Outback or the Barrier Reef from eutrophication? Weird....

Cheers,


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## Potatis (26 Jan 2013)

Heh, I don't think there is any particular control on the sales of fertilizer here.  My guess is that it's a small market, and one main wholesaler imports Rexolin APN and distributes it to other sellers. I'm sure I could order CSM+B from overseas.


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## Potatis (4 Feb 2013)

Just a follow up on this.

I found the final answer to my woes was to use activated carbon in my filter. Even the half dose made the water yellow, but now with the activated carbon the water is crystal clear. There's no need to cry myself to sleep any longer.


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## ceg4048 (4 Feb 2013)

Glad that you were able to sort that out with something simple mate.

Cheers,


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