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Help in getting the right EI dose

Mortis

Member
Joined
17 Jun 2009
Messages
360
Hi guys, Gonna be setting up a 12" cube soon (6.5 gals) and needed help in sorting out the right EI dosage for my tank.
It will only contain Dwarf Hairgrass, Utricularia, Fissidens, Blyxa japonica and Rotala wallichi. Most of the tank is going to be filled with foreground plants and moss and so the growth rate and nutrient uptake is going to be slow, if Im right ?

Now I know an important part of EI dosing is to have excess nutrients, but I am not sure by how much and since my tank would have a nutrient uptake rate lower than, say a tank with more stems I would need a lower fert dosing rate than a more balanced tank.

Basically, I need help determining the fert dosage and dosing regimen for a 6.5 gal tank with maybe around 20 % lower requirements ? I will be preparing stock solutions to a volume of 500ml and dosing with that. The tank will be high light with DIY CO2 and Excel. I realy need help with the calculations cos Im blahblahblahblah at maths.

Thanks !
 

ceg4048

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11 Jul 2007
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Mortis said:
Now I know an important part of EI dosing is to have excess nutrients, but I am not sure by how much and since my tank would have a nutrient uptake rate lower than, say a tank with more stems I would need a lower fert dosing rate than a more balanced tank.
Hi,
The important part of EI has nothing to do with excess nutrients. This is a false mantra. The important part of EI is to make sure that the nutrient levels in the tank never fall below the minimum required plant uptake for the given environmental conditions. You have no idea whether a unilateral 20% decrease in dosage will take you below that level. That will depend on the lighting intensity, the CO2 levels, the flow and the nutrient level present in your water supply. Dosage level adjustment should be done empirically, i.e. by making small adjustments over time. It could easily turn out that you need to add more, not less, for example.

Review the the EI article in the Tutorial section EI DOSING USING DRY SALTS

A sample dosing scheme is provided there for a reference 20G tank. For the sake of simplicity, you can just divide the numbers by half and pretend that the tank is a 10G.

So for a one month supply, you'd add 1 tsp KNO3 + 1/2 tsp KH2PO4 (+ an optional 3 tsp MGSO4) to you 500ml bottle and dose 500/12, or about 40ml per dose. For the trace element mixture, you'd just add a quarter teaspoon to whatever volume you like and each dose would be the chosen volume divided by 12.

After about three weeks, if there are no deficiencies you can start to lower the dosages incrementally when you prepare subsequent mixtures, say, by 10% at a time, and then make an assessment over the following 3 weeks.

Hope this makes sense. ;)

Cheers,
 

Mortis

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Thread starter
Joined
17 Jun 2009
Messages
360
Thanks, that was helpful. Tom Barr does have a guide for dosing 10G tanks on his website. Ill start with that and reduce the amounts by about a third which should suit my needs well.
What I meant by excess nutrients was nutrients provided in an amount which is more than sufficient for the plants. I guess the wording was a bit off but I did mean nutrients dosed in amount that does not limit their supply to plants. I just wanted to know on average how much more than "enough" is added to a tank ?

When I said that I wanted to dose at 20% less than normal, it was a rough estimate that I thought would be fine since my tank would have a lower plant mass. I dont want there to be an excess of nutrients to build up in the tank as I prefer to do smaller water changes rather than the recommended EI 50% weekly water change. Just trying to get the dosage just right.
 

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