"EI Light" dosing questions.

[vidiots]

I was going over both your articles on EI and noticed some things I didn't understand and was hoping that someone could explain them to me.

The first thing I noticed was in the dosing examples you give that you seem to dose roughly twice as much in parts per million for a large tank as you do for a small tank. I'm just wondering why you wouldn't dose for the same levels in a 10gal tank as you do in a 100gal tank? The reason I ask is that I have a 180 gal tank, should I extrapolate this rate of increase outward beyond the examples you give?

The second thing I noticed is that in your article you state that maximum uptake rate of PO4 is 0.2 to 0.6 ppm/day, but if I did the math correctly the starting amounts you suggest in your examples works out to a daily dose of 1.5ppm of PO4. It just seems to me that 1/2 that amount would provide a dose of 0.75ppm/day which is still more than the 0.6ppm/day max uptake rate. Are there other processes going on in the tank that remove PO4 besides what the plants uptake that I am not factoring in?

 

[quenton]

Re: "EI Light" dosing questions.

I was going over both your articles on EI and noticed some things I didn't understand and was hoping that someone could explain them to me.

The first thing I noticed was in the dosing examples you give that you seem to dose roughly twice as much in parts per million for a large tank as you do for a small tank. I'm just wondering why you wouldn't dose for the same levels in a 10gal tank as you do in a 100gal tank? The reason I ask is that I have a 180 gal tank, should I extrapolate this rate of increase outward beyond the examples you give?

The second thing I noticed is that in your article you state that maximum uptake rate of PO4 is 0.2 to 0.6 ppm/day, but if I did the math correctly the starting amounts you suggest in your examples works out to a daily dose of 1.5ppm of PO4. It just seems to me that 1/2 that amount would provide a dose of 0.75ppm/day which is still more than the 0.6ppm/day max uptake rate. Are there other processes going on in the tank that remove PO4 besides what the plants uptake that I am not factoring in?

I believe tom is away for a few days, but I suspect you well get a number of other responses here, then his a bit later.

So ...

• I don't see your "double" for large tanks compared to small. I DO see, and have commented on before - a slight increase for larger tanks. If you look at the 10-20 vs the 100 to 125, which is (because of the range difference) a bit less than 10x the size, you get say 1/8 to 1 1/2 -- 1/8 x 10 is 1 1/4, so yes its a bit more -- but I don't see double.
• re the PO4 -- not sure I see your math -- if you take say a 100g tank, I see a 1/2 tsp 3x a week, which is 1/4 (a bit less) a day if you dosed every day. That seems to me to give about 1ppm per day which is not that much above the uptake? And due to the 50% water change weekly, it won't accumulate.

 

[VaughnH]

Re: "EI Light" dosing questions.

I don't think you can use a fixed number for the uptake rate of any fertilizer. Obviously, if you have a single anubias nana in a 100 gallon tank the uptake rate is far less than if you have 5 large sword plants, or a tank full of H. difformis. As I understand EI the goal is to always have more than what the plants need available to them. And, what they need varies with how much light you are providing. We make no effort at all to fine tune the amounts we dose, other than to watch the plants for obvious symptoms of deficiencies. It is the changing of large percentages of the water in the tank which lets us follow this scheme without worry.

 

[quenton]

Re: "EI Light" dosing questions.

I have to admit that the first time I read the EI document (the full blown one, not the EI-Light) I was "insulted" -- I had been doing things the "right way" (much more work than EI) for some time, and how could anyone suggest NOT testing, changing 50%!!! of the water each week, and dosing LOTS of the stuff that created algae.

I proceeded to ignore it all for a number of months, then I started reading lots of the posts here.

Since I started using EI (reluctantly at first, figuring my algae would take over the world), my tanks have been in great shape, and I have lots more time (not testing every other day to see why this bit of algae is there, or that bit got worse).

 

[Tom Barr]

Re: "EI Light" dosing questions.

And folks have been skeptical initially for over 10 years.......

Main thing is for them to try it, then see.
Same for things like the ADA soil and other things that make it easy and are worth the $$$ like KNO3 etc........


Regards,
Tom Barr

 

[vidiots]

Re: "EI Light" dosing questions.

You are correct, I double checked my math found a mistake and fixed it and it is not Double the dosage for larger tanks but it is still 1.6 times as much for a 100gal tank as it is for a 10gal tank.

I will post my math and maybe you can tell me what I am doing wrong.
100gal dose = 0.5tsp 3x per week KH2PO4
10gal dose = 0.03125tsp 3x per week KH2PO4
KH2PO4 is 70.84% PO4

0.5 /100 = 0.005 tsp / gal
0.03125 / 10 = 0.003125 tsp / gal
0.005 / 0.003125 = 1.6 times as much for a 100gal than a 10gal tank.


0.5tsp * 3 / 7 = 0.214285714 tsp/day (100 gal tank)
0.214285714 tsp * 4.92892159375mL/tsp = 1.056197484mL
1.056197484mL KH2PO4 * 70.84% = 0.748182043 mL PO4
100 gal = 378541.1784 mL
0.748182043 mL PO4 / 378541.1784 mL * 1,000,000 = 1.97649 ppm PO4/day

Doing the same math for a 10 gal tank I get 1.2353 ppm PO4/day.

If you average the two results its roughly 1.6 ppm P04/day
Which just seems excessive to me if the max uptake rate is 0.6 ppm/day.
I understand that the idea is not to have a shortage, but why 2.6 times the max amount you would need? I just seems very wasteful.

 

[Tom Barr]

Re: "EI Light" dosing questions.

0.7ppm PO4 is wasteful?

Probably not.

I have 5 lbs of KH2PO4, see how long that will last for a 100 gal tank.

If you like 1ppm of PO4, you can do that, if you like 2ppm, you can do that, most see to like 2ppm and most have higher stocking levels in larger tanks.

I did not come up with those amounts in the example for EI, but..........they seem fine and will not have issues, if you want more, go for it, if not, that's fine as well.

It's not set in stone. There's no absolution here with levels...............and that's a good thing.

Why would that be a good thing?
Give that some thought.

It provides a lot of variation in us, teaspoons, plants needs(they have a wide range of nutrients that they can adapt and grow in) etc......

Regards,
Tom Barr