RCS and APN micro mix

[cazandchris]

Hi Folks

I have been using Rexolin APN micro mix for a while now with great success as a trace mix.

Here is the Product specification.
Elements ratios:
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%

My question is this....
I have a 40 g tank and have been dosing 7mls (1TBS/250mls) daily...
Will the copper concentration be too high for me to keep Red Cherry Shrimp?

Many Thanks

 

[Tug]

RCS are as near bullet proof as a shrimp can get. I started with three or four and have plenty of shrimp to go around. The LC50 for CuSO4 is around 0.46ppm for cherry shrimp. Water with less then 0.15ppm should be home free. APN, would add a little more then twice as much copper then Plantex. That would put each dose at around 0.05ppm, I think.

 

[nipat]

40 g tank and have been dosing 7mls (1TBS/250mls)

1TBS ~ 16 g = 16,000 mg

16,000 ÷ 250 = 64 mg/ml

7 ml = 7 x 64 = 448 mg

448 x 0.25 ÷ 100 = 1.12 mg of Cu

40 g = 151.4 L


You are adding Cu 1.12 ÷ 151.4 = 0.0074 PPM daily.
The highest long-term possible CU accumulation (from your fert) in your tank
with 50% water change every week = 0.0074 x 7 x 2 = 0.1036 PPM.

However your Cu is in chelated form which has lower toxicity.

 

[Tug]

Thanks nipat for backing up the math. Am I correct that the 0.0074 PPM is for 1mL of the stock solution added to 40 gallons? Which is about 0.05 PPM per 7mL dose.

 

[nipat]

Thanks nipat for backing up the math. Am I correct that the 0.0074 PPM is for 1mL of the stock solution added to 40 gallons? Which is about 0.05 PPM per 7mL dose.

Ah no, it is for 7 ml (which contains 448 mg of the traces).

 

[Tug]

Ah, ok then. Why for a week is the dose = 0.0074 x 7 x 2 = 0.1036 PPM? I am not sure what the (7 x 2) is all about. And, how did you find the TBSP conversion to weight. Something I could not find. I have to say I was hesitant to do the math without that information. I should have followed my instincts. Sorry to ask all these questions, but I would like to get this right. I don't want to make the same bone headed mistake.

Oh well, if there is one way to learn something around here it's to stick your neck out. Always someone watching that knows more then I do ready to correct anyone that screws up. It's one of the reasons I stay.

 

[nipat]

Because cazandchris doses daily so let's multiply it by 7.
This is the amount of 1 week.

Then, with 50% water change weekly, there will be half of the fert left in the tank, right?
And we still continue dosing...

If we keep doing this, the theoretically highest amount
of fert (without plant consuming it) accumulated in the tank
will be close to 2x the amount of fert you have dosed between
each water change. It will get closer and closer to 2x but never reach it.

The weight of 1 TBSP is applied from the weight of CSM+B.
I think it should be close, because 1 TBSP of my traces weights similarly too.

 

[Tug]

Well Shut My Pie Hole and Pay the Man

It would be a lot easier to check my calculations if I used my own math, but I used the wet.biggiantnerds.com calculator to determine levels of copper. Either I found a problem with the calculator or I used the wrong short cut for determining the tank volume (250/7 x 40 = 1428.5gal) when calculating for stock solution dosing. I have sent an email to Wet to see what might have gone wrong. Thanks again nipat.

 

[Wet]

Hey, Tug.

There's a couple reasons why your calculation is off, though your ideas and logic are sound.

a) Plantex CSM+B is 0.09% Cu, while cazandchris's Rexolin APN is 0.25% Cu.
b) My calc uses 4.3g / tsp (so 12.9g / TBL) for Plantex CSM+B, v nipat's 16g / TBL assumption for Rexolin.

Otherwise, again, your logic is good.

Added Rexolin APN to http://wet.biggiantnerds.com/fe_calc.pl so you can play and see for yourself to compare vs your own calcs, if you'd like, and to help you out, cazandchris. Also extended to three places past the decimal point since you guys are, too. *

For clarity for anyone not following along, Tug's conversion with liquid dosing is essentially the same as nipat is doing. Since my calc doesn't currently have fields for liquid dosing (though there is a new calc coming from hariom with his dev and my collaboration that you will love - coming soon!), you can trick mine into doing liquid dosing by:

tank gallons (or liters) for calculator = real tank gallons (or liters) * volume of solution / dose of solution

To get your per dose amounts.

Hope this helps!

* I am not using nipat's assumption of 16g / TBL for weight, though -- I'd prefer if cazandchris or someone else can get me weights per tsp or TBL of a few trials? (If you try to use tsp, it will error and give you the APC link for that calculator.)

 

[cazandchris]

Hi Folks
Thanks for replies!
I decided to go ahead and get the shrimp anyway and see just how bullet proof they are.
So far so good at this 7ml daily dose!

Wet :According to my scales 1TBS of Rexolin weighs 10g....
Thanks again for all your input...