Dosing ferts as dry

[quenton]

When I calculate fert doses (EI), and changing 1/3 water each week and dosing 3x a week in a 60g tank, I get amounts like

KNO3 1/7 tsp
K2SO4 1/10 tsp
Mg 1/12 tsp
KH2PO4 1/90 tsp
Trace 1/3 tsp

OK, but I can't do those kinds of amounts (well 1/3 perhaps).
I would rather than have to keep 5 little bottles in the fridge, or my wife
would not anyway. I was thinking of something like -- keeping 2 weeks
worth in a small bottle (dry), and then being sure that it got used
reasonably evenly over the 2 weeks. Anyone have suggestions??

 

[carpguy]

Change 1/2 of the water weekly and dose twice a week? I think that's the EI protocol. The water change to reset is an important part of the idea: its what makes the Estimating an OK thing. Increasing the dosing and cutting the waterchange isn't really EI any more.

There isn't any special reason the mix would need to stay in separate bottles or necessarily in the fridge (it fades into the woodwork faster than you think). If not the fridge than how about a closet? Dark should do the trick just as well. And one bottle is fine. Dry is fine, mixing dry with a cup of water helps the dissolving on its way.

You're numbers also seem low. I didn't check everything, but your KNO3 dose is about half of what I'm putting in my 30g, and I'm thinking about bumping that up a bit (accursed algae).

 

[Roan Art]

Agree with CarpGuy.

What you've got outlined there isn't EI, but I think I see what you are trying to do? Maybe?

You are trying to cut the water change to 1/3 per week and in doing that, cutting the dosages to correspond?

Not sure there That KNO3 dose is pretty low for your tank, unless it's really lightly planted.

I'm not following EI per se as I do water changes of 50% every 4 days, but otherwise I use the same dosing as Tom recommends for EI and it works for me. Plants seem to like it a lot, too.

I dose 1 teaspoon KNO3 every other day in my 75gs, so it works out to:

Water change - Dose KNO3
Dose Micros
Dose KNO3
Dose Micros
Water change - Dose KNO3

I use Tom's EI chart for my micros, too.

Roan

 

[quenton]

I suspect my doses look low because they are divided by 3 so I do them 3 times
a week. Thus 3 at 1/7 tsp is really 1/2 tsp at the weekly water change.

In fact its 1 1/2 tsp kick -- so if I look at chuck's calc, for a 60g tank and 20ppm
Nitrate, I get about 1.5tsp, then divide by 3 for 1/3 water change each week and
by 3 to does 3 times a week. That gets to about 1/7 tsp.

 

[jart]

I dose 1/2 tsp KNO3 after 50% WC. Then twice weekly I try to replace what the plants have used.

ie 1/4 tsp on days 3 and 5.
(45 gallon, CO2, 3 wpg)

I think what you are doing is trying to add 20 ppm nitrate over the course of the week but you are not accounting for uptake.

Depending on your light, CO2 status, etc, you could dose to 20 ppm NO3 after your water change, then test later in the week to see what your plants are using.
I dose all my ferts dry, except traces, which I mix with water (1 tablespoon to 250mL water) and keep in the fridge (had 2 batches grow mold).

 

[quenton]

I dose 1/2 tsp KNO3 after 50% WC. Then twice weekly I try to replace what the plants have used.

ie 1/4 tsp on days 3 and 5.
(45 gallon, CO2, 3 wpg)

I think what you are doing is trying to add 20 ppm nitrate over the course of the week but you are not accounting for uptake.

Depending on your light, CO2 status, etc, you could dose to 20 ppm NO3 after your water change, then test later in the week to see what your plants are using.
I dose all my ferts dry, except traces, which I mix with water (1 tablespoon to 250mL water) and keep in the fridge (had 2 batches grow mold).

Hm -- I have been concentrating so much on computing the dry doses to get to
my targe amount, I forgot about uptake. I will watch it over the next couple of weeks
and see what I really should be dosing.

Thanks to everyone.